epidemiologia e oncologia: uma relaÇÃo...
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EPIDEMIOLOGIA E ONCOLOGIA: UMA RELAÇÃO ÍNTIMARELAÇÃO ÍNTIMA
Moysés Szklo
Professor de Epidemiologia e Medicina
Universidade Johns Hopkins
Editor-Chefe, American Journal of Epidemiology
Things have to be as
simple as possible, but
not simpler.
(Einstein)
“Tempo de antecipação”
Detecção precoce (se possível),
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Conceito Fundamental Para o Controle de Câncer: História Natural
Morte, cura ou recidiva
(Baseado em Gordis L. Epidemiology, 3rd edition)
“Tempo de antecipação”
Detecção precoce (se possível),
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
As áreas de pesquisa em câncerse “encaixam” na história natural
Morte, cura ou recidiva
Avaliação de programas de atenção a pacientes terminais
Estudos de fatores prognósticos biológicos, ambientais e terapêuticos
Estudos de fatores determinantes de atraso diagnóstico
Estudos de avaliação de programas de detecção precoce (rastreamento/ prevenção secundária)
Estudos de processo e estrutura do sistema de atenção à saúde
Estudos de qualidade de vida
“Tempo de antecipação”
Detecção precoce (se possível),
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
Prevenção secundária
(rastreamento)
Prevenção terciária• Prevenção de exposição
a fatores de risco• Cessação de exposição
Prevenção primária:
Estudos epidemiológicos
• Estudos experimentais (ensaios clinicos) e estudos observacionais
“Tempo de antecipação”
Detecção precoce (se possível),
Início da exposição a fatores de risco
Início “da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
PrevenPrevenPrevenção ção ção secundsecundsecundáááriariaria
PrevenPrevenPrevenção tercição tercição terciáááriariaria• Prevenção de exposição
a fatores de risco• Cessação de exposição
Prevenção primária:
Prevalência de tabagismo entre adultos de 18 anos ou mais de idade e estratégias nacionais de controle de tabaco implementadas entre 1986 e 2008
O GRANDE SUCESSO DA PREVENÇÃO PRIMÁRIA
(Adaptado de Figueiredo VC [Tese de Doutorado]. RJ: Instituto de Medicina Social, UERJ, 2007)
Environment
Primary Prevention of Cancer Is Based on the Epidemiologic Triad of
Risk Factors
Agent
Human host
Vector
Environment
Primary Prevention of Cancer Is Based on the Epidemiologic Triad of
Risk Factors Three basic strategies in
primary prevention
- Kill the agent and/or the vector
- Make the environment hostile to the agent
- Increase human host’s resistance
Agent
Human host
Vector
Environment: air
Vector: tobacco
Primary Prevention of Cancer Is Based on the Epidemiologic Triad of
Risk Factors – Example: Tobacco Exposure
Example: Prohibition of indoor smoking
Example: Decrease in
Example: lobby against tobacco
industry
Agent: tobacco
Human Host: behavior
Vector: tobacco industry
Example: Health education, smoking cessation therapy
Decrease in tobacco
cultivation
Risk Factors (Causes) for Cancer Established by Epidemiologic Research: Some Examples
• Estrogen replacement therapy and breast and endometrial cancers
• Asbestos and respiratory cancer
• Smoking and cancers
• Ionizing radiation and cancers
• Down’s syndrome and leukemia
• Helicobacter pylori and gastric cancer
• HPV and cervical cancer
• Obesity and post-menopausal breast cancer
• Diet low in fibers and colon cancer
COMO SÃO GERADAS AS HIPÓTESES SOBRE FATORES DE RISCO (ETIOLOGIA) DE CÂNCER?
Epidemiologia é a arte de olhar
A melhor estratégia de
análise de dados é olhar
os dados e pensar no que os dados e pensar no que
se está vendo.
(G. W. Comstock)
Generating Hypothesis from Descriptive (Available) Population Data: Average Annual Breast Cancer Age-specific Incidence Rates per 100,000, USA 1997-
2001 (based on SEER data)
40
50
60
70
80
90
100
3-D Column 1
3-D Column 2
3-D Column 3
Inciden
ce Rates/ 100,000
0
10
20
30
40 3-D Column 3
Age 50-5430-34 75+
Inciden
ce Rates/ 100,000
The decrease in the slope at around menopause led to the hypothesis that breast cancer is estrogen-dependent, which was subsequently confirmed in analytic
epidemiologic studies
Smoking
High Salt Intake
High intake of processed foods
H. Pylori
Modelo de causalidade de Rothman
Causa suficienteConstelação de
componentes causais que, quando presente,
causa inevitavelmente a
O MODELO DE ROTHMAN EXPLICA DOIS FENÔMENOS RELACIONADOS
-POPULAÇÕES COM PREVALÊNCIA ELEVADA DE UM COMPONENTE CAUSAL OU UMA CAUSA NECESSÁRIA (FATOR DE RISCO) TÊM RISCO BAIXO DA ENFERMIDADE ���� FALTAM COMPONENTES CAUSAIS QUE COMPLETEM AS CAUSAS SUFICIENTES;
- ELIMINAÇÃO DE UM FATOR DE RISCO (COMPONENTE CAUSAL) DIMINUI O RISCO DA ENFERMIDADE ���� TODOS AS CAUSAS SUFICIENTES QUE CONTÊM O COMPONENTE CAUSAL SÃO ELIMINADAS
Taxa
s p
or
10
0 0
00
Taxas de mortalidade por câncer, ajustadas por idade, sexo feminino, Estados Unidos 1930-2001
(American Cancer Society, 2005)
causa inevitavelmente a doença
(American Cancer Society, 2005)
Smoking
High Salt Intake
High intake of processed foods
H. Pylori*
Causa necessária, mas não suficiente
Smoking
High Salt Intake
High intake of processed foods
H. Pylori
Modelo de causalidade de Rothman
Causa suficienteConstelação de
componentes causais que, quando presente,
causa inevitavelmente a
O MODELO DE ROTHMAN EXPLICA DOIS FENÔMENOS RELACIONADOS
-POPULAÇÕES COM PREVALÊNCIA ELEVADA DE UM COMPONENTE CAUSAL OU UMA CAUSA NECESSÁRIA (FATOR DE RISCO) TÊM RISCO BAIXO DA ENFERMIDADE ���� FALTAM COMPONENTES CAUSAIS QUE COMPLETEM AS CAUSAS SUFICIENTES;
- ELIMINAÇÃO DE UM FATOR DE RISCO (COMPONENTE CAUSAL) DIMINUI O RISCO DA ENFERMIDADE ���� TODOS AS CAUSAS SUFICIENTES QUE CONTÊM O COMPONENTE CAUSAL SÃO ELIMINADAS
Taxa
s p
or
10
0 0
00
Taxas de mortalidade por câncer, ajustadas por idade, sexo feminino, Estados Unidos 1930-2001
(American Cancer Society, 2005)
causa inevitavelmente a doença
(American Cancer Society, 2005)
Smoking
High Salt Intake
High intake of processed foods
H. Pylori*
Causa necessária, mas não suficiente
Tempo de antecipação
Detecção precoce éfeita,
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Momento em que a detecção
precoce se torna possivel
Fase pré-clínica detectável (FPCD)
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
••• Prevenção da exposição Prevenção da exposição Prevenção da exposição a fatores de riscoa fatores de riscoa fatores de risco
••• Cessação de exposiçãoCessação de exposiçãoCessação de exposição
Prevenção primária:Prevenção primária:Prevenção primária: Prevenção secundária
(rastreamento)
PrevenPrevenPrevenção tercição tercição terciáááriariaria
“Tempo de antecipação”
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Momento em que a detecção
precoce se torna possivel
Fase pré-clínica detectável (FPCD)
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
••• Prevenção da exposição Prevenção da exposição Prevenção da exposição a fatores de riscoa fatores de riscoa fatores de risco
••• Cessação de exposiçãoCessação de exposiçãoCessação de exposição
Prevenção primária:Prevenção primária:Prevenção primária: Prevenção secundária
(rastreamento)
PrevenPrevenPrevenção tercição tercição terciáááriariaria
“Tempo de antecipação”
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Momento em que a detecção
precoce se torna possivel
Fase pré-clínica detectável (FPCD)
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
••• Prevenção da exposição Prevenção da exposição Prevenção da exposição a fatores de riscoa fatores de riscoa fatores de risco
••• Cessação de exposiçãoCessação de exposiçãoCessação de exposição
Prevenção primária:Prevenção primária:Prevenção primária: Prevenção secundária
(rastreamento)
PrevenPrevenPrevenção tercição tercição terciáááriariaria
Critical Point: A point in the natural history of the disease before which therapy may be less difficult and/or more
ANOTHER CRITICAL CONCEPT IN CANCER
CONTROL: THE CRITICAL POINT
before which therapy may be less difficult and/or more effective (If this disease is potentially curable, cure may be
possible before this point, but not after)
(Baseado em Gordis L. Epidemiology, 3rd edition)
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
Effective early diagnosis
Detectable PreclinicalPhase
(Adapted from Gordis,Epidemiology, 1996)
NATURAL HISTORY OF A DISEASE
When should early diagnosis be made?Critical point
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
When should early diagnosis be made?Critical point
Detectable PreclinicalPhase
(Adapted from Gordis,Epidemiology, 1996)
NATURAL HISTORY OF A DISEASE
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
When should early diagnosis be made?Critical point
NOT NECESSARY!
Detectable PreclinicalPhase
(Adapted from Gordis,Epidemiology, 1996)
NATURAL HISTORY OF A DISEASE
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
Effective early diagnosis
Detectable PreclinicalPhase
Critical point IN CERVICAL CANCER, THE DPCP PRIOR TO THE CRITICAL POINT IS LONG: SCREENING EVERY 3 YEARS IS FAIRLY CONSERVATIVE
(Adapted from Gordis,Epidemiology, 1996)
NATURAL HISTORY OF A DISEASE
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
Effective early diagnosis
Detectable PreclinicalPhase
NATURAL HISTORY OF A DISEASE
Critical point IN BREAST CANCER, THE DPCP PRIOR TO THE CRITICAL POINT IS RELATIVELY SHORT:
SCREENING EVERY TWO YEARS IS REASONABLE (DPCP ∼3.3 years for post-
menopausal women; ∼1.7 years for <50 years old) (Tabar, et al, Cancer 1995;75:2507-17; Tabar et al, Int
J Cancer 1996;66:413-9)(Adapted from Gordis,Epidemiology, 1996)
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable PreclinicalDetectable PreclinicalPhase
NATURAL HISTORY OF A DISEASE
Critical point IN LUNG CANCER, THE DPCP PRIOR TO THE CRITICAL POINT IS SO SHORT THAT
SCREENING IS NOT EFFECTIVE
(Adapted from Gordis,Epidemiology, 1996)
Biologiconset
A
Earliestpoint whendiagnosis ispossible
B D
Usualdiagnosisbased onsymptoms
Detectable Preclinical
1 2 3
Screening is ineffectivecure
Survival* 2 yrs
Survival* 5 yrs
Detectable PreclinicalPhase
NATURAL HISTORY OF A DISEASE
Critical point Most diseases have multiple critical points; thus, the earlier the
diagnosis, the better the prognosis
*corrected for lead time
(Adapted from Gordis,Epidemiology, 1996)
A2004 20101995
Diagnosis based on symptoms Death
Disease onset
Survival= 6 years
Patient
NATURAL HISTORY OF CANCER IN PATIENTS A AND B IS THE SAME
A KEY NOTION WHEN EVALUATING SURVIVAL OF PATIENTS WITH CANCER: LEAD TIME BIAS
B2002 20101995
Early diagnosis DeathDisease
onset
Survival= 8 years
Lead timePatient
Survival B = Survival A + lead time
Conclusion: Screening was not effective
A2004 20101995
Diagnosis based on symptoms Death
Disease onset
Survival= 6 years
Patient
NATURAL HISTORY OF CANCER IN PATIENTS A AND B IS DIFFERENT
A KEY NOTION WHEN EVALUATING SURVIVAL OF PATIENTS WITH CANCER: LEAD TIME BIAS
B2002 20101995
Early diagnosis Death
2012
Disease onset
Survival= 10 years
Lead timePatient Net gain
Survival B > Survival A + lead time
Conclusion: Screening was effective
100%Natural History of a
Disease: Lead Time Bias in Survival Analysis(Adapted from Frank, Am J Prev
1985;1:3-9)
40%
70%
Lead time bias
Cu
mu
lativ
e S
urv
iva
l
40%
5 years after usual diagnosis
5 years after early diagnosis
3 5 10 12
Lead Time
Usual diagnosis
Cu
mu
lativ
e S
urv
iva
l
-2Early
diagnosis
(Baseado em Gordis L. Epidemiology, 3rd edition)
50
60
70
80
Lead-Time- Adjusted Five-Year Survival Among Breast Cancer Patients in Shapiro et al’s Randomized Clinical Trial
(Shapiro et al, JNCI 1982;69:349-55)
0
10
20
30
40
2nd QtrTotal Allocated to Screening
Control
Overdiagnosis Bias: Bleyer AB & Welch HG. Effect of Three Decades of Screening Mammography on Breast Cancer Incidence. New Eng J Med
2012;367:1998-2005.
• Effective cancer screening should increase the incidence of disease detected at an early stage and decrease late stage disease
• Examination of breast cancer incidence trends from 1976 through 2008, taking into account the transient excess incidence associated with hormone replacement therapy and adjusting for trends in the incidence of women younger than 40 years (that is, women without screening)
• During this period, incidence of early stage breast cancer doubled (an absolute increase of 122 cases per 100 000 women)
• The rate of late stage breast cancer decreased by 8% (from 102 to 94 cases per 100 000 women), corresponding to 8 cases.
• Thus, only 8 of the 122 cases were thus expected to progress to advanced disease
• It is estimated that in 2008 breast cancer was overdiagnosed in more than 70 000 women (31% of all breast cancers diagnosed)
Assumptions Justifying a Screening Program
• All or most clinical cases of a disease first go through a detectable pre-clinical phase prior to the last critical point, and
• In the absence of intervention, all or most cases in a pre-clinical phase progress to the clinical phase.phase progress to the clinical phase.
• Prognosis (recurrence free survival and survival) improve with early diagnosis
Causas de baixa efetividade de um programa de rastreamento
“Tempo de antecipação”
Detecção precoce (se possível),
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Morte, cura ou recidiva
• Tempo de antecipação é curto (ex: câncer de pulmão)
• O tempo de antecipação é longo, mas a terapia não é eficaz
• A terapia é eficaz, mas o sistema de atenção à saúde é falho
“Tempo de antecipação”
Detecção precoce éfeita,
Início da exposição a fatores de risco
Início da enfermidade
Detecção baseada em sintomas e sinais, que ocorre com atraso depois do início da fase clínica
Detecção baseada em sintomas ou sinais que ocorrem no início da fase clínica,
Momento em que a detecção
precoce se torna possivel
Fase pré-clínica detectável (FPCD)
Correspondência entre as diferentes fases da história natural do
câncer e níveis de controle
Morte, cura ou recidiva
••• Prevenção da exposição Prevenção da exposição Prevenção da exposição a fatores de riscoa fatores de riscoa fatores de risco
••• Cessação de exposiçãoCessação de exposiçãoCessação de exposição
PrevençãoPrevençãoPrevenção primáriaprimáriaprimária::: PrevenPrevenPrevenção tercição tercição terciáááriariariaPrevençãoPrevençãoPrevençãosecundáriasecundáriasecundária: : :
rastreamentorastreamentorastreamento
EXPERIMENTAL (RANDOMIZED CLINICAL TRIAL)
Study Sample
Designs Used in Clinical Research (Clinical Epidemiology)
Random Allocation
Outcome Outcome
Follow-up
Intervention Control
100)(
)()(×
−=
GroupControlinIncidence
GrouponInterventiActiveinIncidenceGroupControlinIncidenceEfficacy
Randomized Clinical Trials of Screening for Prostate Cancer
Experimental Epidemiology: the Randomized Clinical Trial
Cumulative mortality. Schroder FH, et al. New Eng
J Med 2009;360:1320-8 (USA)
Cumulative number of deaths. Andriole GL et al, New Eng J
Med 2009;360:1310-9 (Europe)
Randomized Clinical Trial: Recurrence and Breast Cancer Mortality in 6846 Women with ER-positive Disease
Recurrence Mortality
(Davies C, Pan H, Godwin J, et al. Long term effects of continuing adjuvant tamoxifen to 10 years versus stopping at 5 years after diagnosis of oestrogen receptor-positive breast cancer:ATLAS, a randomised trial. Lancet 2012 [Electronic publication])
Two Designs Used in Clinical Research
(Clinical Epidemiology)
NON-EXPERIMENTAL (OBSERVATIONAL)
Study Sample
Non-Random Allocation
Study Sample
Random Allocation
EXPERIMENTAL (RANDOMIZED CLINICAL TRIAL)
Follow-up
Factor (+) Factor (-)
Outcome OutcomeOutcome Outcome
Follow-up
Intervention Control
Observational Study: Kaplan-Meier curves of survival after diagnosis of breast cancer. HER2 human epidermal growth factor receptor-2-positive; HR hormone receptor
(estrogen and/or progesterone); TN triple negative (estrogen, progesterone and HER2 negative)
All HR+
Stearoyl-CoA desaturase 1
(SCD1): essential regulator of fatty acid synthesis. Overexpression increases the
growth of breast
(Holder AM, Gonzalez-Angulo AM, Chen H, et al. High stearoyl-CoA desaturase 1 expression is associated with shorter survival in breast cancer patients. Breast Cancer Res Treat [epubl, Dec 2012])
HER2+TN
growth of breast cancer cell line.
It is the inverse of the difference in mortality between the control and the active intervention
groups. For example, if the mortality rate in the control group is 30% and in the active
intervention group it is 10%, the difference is 20% Thus, if for every 100 individuals, 20
deaths are prevented, to prevent 1 death, 1/0.2= 5.
How is the number that needs to be screened/treated to prevent one death calculated?
Detour: A USEFUL STATISTIC: THE NUMBER OF PEOPLE WHO HAVE TO BE TREATED TO PREVENT ONE EVENT
deaths are prevented, to prevent 1 death, 1/0.2= 5.
FOR EVERY 100 TREATED/SCREENED PERSONS 20 DEATHS ARE AVOIDED
1 AVOIDED DEATHx?
X= (100 × 1) ÷ 20= 5
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive and curative strategies;
Some Key Objectives of Epidemiology(All Relevant to Cancer Control)
• Translate epidemiologic findings into public health policies.
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive and curative strategies;
Some Key Objectives of Epidemiology(All Relevant to Cancer Control)
• Translate epidemiologic findings into public health policies.
TRANSLATIONAL EPIDEMIOLOGY
Aplicação da politica: planejamento
• Evidências• Obstáculos
Políticas baseadas em evidências
• Colaboração Cochrane
• Outras fontes (meta-análises publicadas em
Revisões sistemáticas
Custo-efetividade
Análise de sensibilidade
• Ensaios aleatorizados
• Estudos de coorte
• Estudos de casos e
Aquisição de evidências científicas
Processo de Implementação de Politicas de Controle do Câncer Baseadas em Evidências
• Obstáculos
• Avaliação de níveis de evidência
• Seleção de opções programáticas (análise de decisão)
• Recomendações
publicadas em revistas)
• Revisões Sistemáticas e meta-análisesrealizadas de
novo
• Estudos conduzidos de
novo
• Estudos de casos e controles
• Estudos de séries temporais
• Estudos de processo e estrutura
Tradução de conhecimentos(Modificado de Dickersin K)
Levels of Evidence on Effectiveness
• Meta-analysis of randomized trials
• Individual randomized trial of high quality
• Dramatic changes in the incidence/mortality after introduction of a given program (e.g., St Jude protocol and survival of acute lymphocytic leukemia in children)
• Meta-analysis of cohort studies
better
• Individual cohort study of high quality
• Meta-analysis of case-control studies
• Individual case-control study of high quality
• Expert opinion not based on the aboveworse
Forest plot of the effect of group counselling on the incidence of smoking abstinence. Use of nicotine patch, bupropion, and notriptyline varied among studies (Motillo S, et al. Eur Heart J 2008 [Epub ahead of print Dec 24]
Interface between epidemiology and the
decision-making process
• Meta-Analysis
• Decision Analysis
Evaluation of effectiveness
• Decision Analysis
• Cost-Effectiveness Analysis
(Pettiti DB. Meta-Analysis, Decision Analysis and Cost-Effectiveness Analysis. New
York, Oxford, Oxford University Press, 1994)
Interface between epidemiology and the
decision-making process
• Meta-Analysis
• Decision Analysis
Evaluation of effectiveness
• Decision Analysis
• Cost-Effectiveness Analysis
(Pettiti DB. Meta-Analysis, Decision Analysis and Cost-Effectiveness Analysis. New
York, Oxford, Oxford University Press, 1994
Meta-Analysis
Summary of the
efficacy/effectiveness of the
intervention
Decision Analysis
Assessment of the relative value of the
programmatic options, based on their
community effectiveness (ideally determined
by meta-analysis)
Relations between meta-analysis, decision analysis and cost-
effectiveness analysis
intervention
Cost-effectiveness Analysis
Assessment of the cost of the program, based on the relative value
of the options
Decision Analysis: uses a quantitative approach to evaluate the relative value (effectiveness) of one or more interventions, programs or services.
Steps in Decision Analysis
• Identification and description of the problem
• Collection of the information needed to construct the decision tree (ideally by means of meta-analysis) decision tree (ideally by means of meta-analysis)
• Construction of a decision tree
• Analysis of the decision tree
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes
For those who tolerate the intervention, D has a lower
mortality than C
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes
For those who tolerate the interventions, D has a lower
mortality than C
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes However, tolerance is better for Program C
Thus,C: better tolerance, higher mortalityD: worse tolerance, lower mortality
Table 2a – Program C: less efficacious but better drug tolerance (70%)
Tolerance? Joint probability of death
Yes 0.70 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
0.30 x 0.90 x 0.50= 0.135
Table 2b – Program D: more efficacious, but less drug tolerance (only 30%)
Tolerance? Joint probability of death
Yes 0.30 ×××× 0.10 ×××× 0.05= 0.0015
0.30 ×××× 0.90 ×××× 0.10= 0.027
No 0.70 ×××× 0.10 ×××× 0.50= 0.035
0.70 ×××× 0.90 ×××× 0.50= 0.315
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
0.70 ×××× 0.90 ×××× 0.50= 0.315
0.0015+ 0.027 + 0.035 + 0.315= 0.3785 or 37.85%
Conclude: Program D is more efficacious (i.e., those who tolerate the drug have a lower mortality than in Program C), but because tolerance to Program C is higher, its community effectiveness is higher.
Community effectiveness of C (compared with D)= {[37.85% - 28.30%] ÷ 37.85%} ×100= 25.2%
THE ENDTHE END
Objectives of Epidemiology(All Relevant to Cancer Control)
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons (e.g., age, gender), time and place;
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive and curative strategies;
• Translate epidemiologic findings into public health policies.
Who, 2010. Global status report on noncommunicable diseases 2010
Homens195190
Mulheres189150
Número estimado de casos novos, por sexo, Brasil, 2012
Localização Primária Casos novos
%
Próstata 60180 30,8
Traqueia, Brônquios e Pulmão
17210 8,8
Localização Primária Casos novos
%
Mama 52680 27,9
Colo do útero 17540 9,3
Cólon e reto 15960 8,4
*Fonte:: MS/INCA/ Estimativa de Câncer no Brasil, 2012MS/INCA/Conprev/Divisão de Informação
Cólon e reto 14180 7,3
Estômago 12670 6,5
Cavidade oral 9990 5,1
Esôfago 7770 4,0
Bexiga 6210 3,2
Laringe 6110 3,1
Linfoma Não-Hodgkin 5190 2,7
Cérebro, Sistema Nervoso 4820 2,5
Cólon e reto 15960 8,4
Tireoide 10590 5,6
Traqueia, Brônquios e Pulmão
10110 5,3
Estômago 7420 3,9
Ovário 6190 3,3
Corpo do útero 4520 2,4
Cérebro, Sistema Nervoso 4450 2,4
Linfoma Não-Hodgkin 4450 2,4
Distribuição das taxas brutas por 100 000 habitantes de incidência
estimadas para o ano de 2008, em homens e mulheres, segundo os
principais tipos de câncer.
52,43
18,86
14,927,93
14,88
9,72
50,71
Próstata
Mama Feminina
Colo do Útero
Traquéia, Brônquio e Pulmão
Estômago
13,23
11,00
8,35
5,52
3,093,03
4,44
2,72
3,88
19,18
60 40 20 0 20 40 60
Cólon e Reto
Cavidade Oral
Esôfago
Leucemias
Pele Melanoma
Fonte: MS/INCA/Conprev/Divisão de Informação
Registros de Câncer de Base Populacional (RCBP)
Situação atual
Dos 32 implantados
27 RCBP estão ativos
**
*
* *
**
***
*
*
*
27 RCBP estão ativos*
*
*
*
*
*
**
**
**
**
*
Situação atual
241 RHC em atividade operacional em
40-75% das informações da bases dedados dos RHC já são transferidasautomaticamente para os RCBP pormeio da exportação do sistemaSisRHC/importação pelo BPW
Registro Hospitalar de Câncer - RHC
241 RHC em atividade operacional em CACON/UNACON
UNACON 87% tem RHC
CACON 100% tem RHC
Objectives of Epidemiology(All Relevant to Cancer Control)
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons(e.g., age, gender), time and place;
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive and curative strategies;
• Translate epidemiologic findings into public health policies.
Taxas de incidência estimadas (não ajustadas) para os tipos de
câncer mais frequentes (exceto câncer de pele não melanoma) em
homens, Brasil e regiões geográficas, 2012*
BrasilRegiãoNorte
RegiãoNordeste
Região Centro-Oeste
Região Sudeste
Região Sul
1ºPróstata (62,54)
Próstata (29,72)
Próstata (43,08)
Próstata (74,65)
Próstata (77,89)
Próstata (68,36)
2ºTraqueia, Brônquio
e Pulmão Estômago (10,67)
Estômago (8,99)
Traqueia, Brônquio e Pulmão
Cólon e Reto (22,12)
Traqueia, Brônquio e Pulmão
BrasilRegiãoNorte
RegiãoNordeste
Região Centro-Oeste
Região Sudeste
Região Sul
1ºPróstata (62,54)
Próstata (29,72)
Próstata (43,08)
Próstata (74,65)
Próstata (77,89)
Próstata (68,36)
2ºTraqueia, Brônquio
e Pulmão Estômago (10,67)
Estômago (8,99)
Traqueia, Brônquio e Pulmão
Cólon e Reto (22,12)
Traqueia, Brônquio e Pulmão
PLACE and PERSON (MEN)
*por 100.000 habitantesFonte: MS/INCA/ Estimativa de Câncer no Brasil, 2011/2012
MS/INCA/Conprev/Divisão de Informação e Análise de Situação
2º e Pulmão (17,90)
(10,67) (8,99)e Pulmão (16,64)
(22,12)e Pulmão (37,02)
3ºCólon e reto
(14,75)
Traqueia, Brônquio e Pulmão (8,11)
Traqueia, Brônquio e Pulmão (8,52)
Cólon e Reto (14,30)
Traqueia, Brônquio e Pulmão (19,73)
Cólon e Reto (18,07)
4ºEstômago (13,20)
Cólon e Reto (3,99)
Cavidade Oral (6,15)
Estômago (13,84)
Estômago (15,52)
Estômago (15,72)
5ºCavidade Oral
(10,41)Leucemias
(3,54)Cólon e Reto
(5,31)Cavidade Oral
(8,58)Cavidade Oral
(14,61)Esôfago (15,27)
2º e Pulmão (17,90)
(10,67) (8,99)e Pulmão (16,64)
(22,12)e Pulmão (37,02)
3ºCólon e reto
(14,75)
Traqueia, Brônquio e Pulmão (8,11)
Traqueia, Brônquio e Pulmão (8,52)
Cólon e Reto (14,30)
Traqueia, Brônquio e Pulmão (19,73)
Cólon e Reto (18,07)
4ºEstômago (13,20)
Cólon e Reto (3,99)
Cavidade Oral (6,15)
Estômago (13,84)
Estômago (15,52)
Estômago (15,72)
5ºCavidade Oral
(10,41)Leucemias
(3,54)Cólon e Reto
(5,31)Cavidade Oral
(8,58)Cavidade Oral
(14,61)Esôfago (15,27)
Leukaemia
BrasilRegião Norte
Região Nordeste
Região Centro-Oeste
Região Sudeste
Região Sul
1ºMama feminina
(52,50)Colo do útero
(23,62)Mama feminina
(31,90)Mama feminina
(47,56)Mama feminina
(68,93)Mama feminina
(64,80)
2ºColo do útero
(17,49)Mama feminina
(19,38)Colo do útero
(17,96)Colo do útero
(27,71)Cólon e Reto
(23,01)Cólon e Reto
(19,85)
BrasilRegião Norte
Região Nordeste
Região Centro-Oeste
Região Sudeste
Região Sul
1ºMama feminina
(52,50)Colo do útero
(23,62)Mama feminina
(31,90)Mama feminina
(47,56)Mama feminina
(68,93)Mama feminina
(64,80)
2ºColo do útero
(17,49)Mama feminina
(19,38)Colo do útero
(17,96)Colo do útero
(27,71)Cólon e Reto
(23,01)Cólon e Reto
(19,85)
Taxas de incidência estimadas (não ajustadas) para os tipos de câncer mais
frequentes (exceto câncer de pele não melanoma) em mulheres, Brasil e
regiões geográficas, 2012*
Breast
PLACE and PERSON (WOMEN)
2º(17,49) (19,38) (17,96) (27,71) (23,01) (19,85)
3ºCólon e Reto
(15,94)Glândula Tireoide
(7,34)Cólon e Reto
(6,66)Cólon e Reto
(14,71)Colo do útero
(15,53)
Traqueia, Brônquio e Pulmão (18,58)
4ºGlândula Tireoide
(10,59)Estômago
(5,83)Glândula Tireoide
(6,01)
Traqueia, Brônquio e Pulmão (9,13)
Glândula Tireoide (15,02)
Colo do útero (13,88)
5ºTraqueia, Brônquio
e Pulmão (10,08)
Traqueia, Brônquio e Pulmão (5,12)
Traqueia, Brônquio e Pulmão (5,64)
Estômago (6,76)
Traqueia, Brônquio e Pulmão (11,22)
Glândula Tireoide (10,28)
2º(17,49) (19,38) (17,96) (27,71) (23,01) (19,85)
3ºCólon e Reto
(15,94)Glândula Tireoide
(7,34)Cólon e Reto
(6,66)Cólon e Reto
(14,71)Colo do útero
(15,53)
Traqueia, Brônquio e Pulmão (18,58)
4ºGlândula Tireoide
(10,59)Estômago
(5,83)Glândula Tireoide
(6,01)
Traqueia, Brônquio e Pulmão (9,13)
Glândula Tireoide (15,02)
Colo do útero (13,88)
5ºTraqueia, Brônquio
e Pulmão (10,08)
Traqueia, Brônquio e Pulmão (5,12)
Traqueia, Brônquio e Pulmão (5,64)
Estômago (6,76)
Traqueia, Brônquio e Pulmão (11,22)
Glândula Tireoide (10,28)
Thyroid
*por 100.000 habitantesFonte: MS/INCA/ Estimativa de Câncer no Brasil, 2011/2012
MS/INCA/Conprev/Divisão de Informação e Análise de Situação
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons (e.g., age, gender), time and place;
Objectives of Epidemiology(All Relevant to Cancer Control)
• Investigate the etiology (risk factors) of disease:
• Assess effectiveness of preventive and curative strategies;
• Translate epidemiologic findings into public health policies.
• Case-control studies• Cohort studies
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons (e.g., age, gender), time and place;
Objectives of Epidemiology(All Relevant to Cancer Control)
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive and curative strategies;
• Translate epidemiologic findings into public health policies.
• Pre-post studies• Quasi-experimental studies• Follow-up studies
- Prognostic studies- Randomized Clinical Trials
1. Estudo Pré-Pós
Mo
rta
lida
de
Inferências causais relacionadas a esse desenho são robustas no caso de
“experimentos naturais” (exemplo: insulina, estreptomicina)
ESTUDOS BASEADOS EM SÉRIES TEMPORAIS UTILIZANDO DADOS DE VIGILÂNCIA
Mo
rta
lida
de
Tempo
Introdução do programa
Outros programas? Mudanças nas características da população alvo?
A= intervençãoB= controle
2. Estudo Quasi-experimental (Pré-Pós com Controles)
ESTUDOS BASEADOS EM SÉRIES TEMPORAIS UTILIZANDO DADOS DE VIGILÂNCIA
Mo
rta
lida
de
A B
A B
Seguimento
(Adapted by Ibrahim M from D. Gillings et al. Am J Pub Hlth 71(1)38-46)
20
30
40
50 (1)(2)
(3)
(4)
(5)Taxas de
mortalidade
perinatal
Antes de o programa ser implementado,
a área que recebeu a intervenção tinha
taxas the mortalidade perinatal mais
elevadas do que a área controle, o que
pode explicar porque foi selecionada para
receber a intervenção
10
20
01935 1945 1955 1965 1975 1985
Intervenção
ControlePrograma
Year
(Adapted by Ibrahim M from D. Gillings et al. Am J Pub Hlth 71(1)38-46)
20
30
40
50 (1)(2)
(3)
(4)
(5)
O aspecto mais importante no estudo quasi-experimental é a comparação dos ângulos
Taxas de
mortalidade
perinatal
10
20
01935 1945 1955 1965 1975 1985
Year
Intervenção
ControlePrograma
Follow-up Studies (Prognostic Studies and RCTs)
time
Initialsample
Finalsample
Events (death, recurrence)
Losses to follow-up
Factor (+)
INCIDENCEFACTOR (+)
time
time
Initialsample
Finalsample
Events (death, recurrence)
Losses to follow-up
Factor (-)
INCIDENCEFACTOR (-)
= RR
Age-Adjusted Death Rates/100 000, Relative Risks, and Attributable Risks for Lung Cancer—Current Cigarette Smokers Vs Nonsmokers, Cancer Prevention Study I and CPS-II*
CPS-I (1959-1965) CPS-II (1982-1988)
Nonsmoker CurrentSmoker
Nonsmoker CurrentSmoker
MenMen
Rate 15.7 187.1 14.7 341.3
Relative Risk 1.0 11.9 1.0 23.2
Women
Rate 9.6 26.1 12.0 154.6
Relative Risk 1.0 2.7 1.0 12.8
Age-Adjusted Death Rates/100 000, Relative Risks, and Attributable Risks for Lung Cancer—Current Cigarette Smokers Vs Nonsmokers, Cancer Prevention Study I and CPS-II*
CPS-I (1959-1965) CPS-II (1982-1988)
Nonsmoker CurrentSmoker
Nonsmoker CurrentSmoker
MenMen
Rate 15.7 187.1 14.7 341.3
Relative Risk 1.0 11.9 1.0 23.2
Women
Rate 9.6 26.1 12.0 154.6
Relative Risk 1.0 2.7 1.0 12.8
Age-Adjusted Death Rates/100 000, Relative Risks, and Attributable Risks for Lung Cancer—Current Cigarette Smokers Vs Nonsmokers, Cancer Prevention Study I and CPS-II*
CPS-I (1959-1965) CPS-II (1982-1988)
Nonsmoker CurrentSmoker
Nonsmoker CurrentSmoker
MenMen
Rate 15.7 187.1 14.7 341.3
Relative Risk 1.0 11.9 1.0 23.2
Women
Rate 9.6 26.1 12.0 154.6
Relative Risk 1.0 2.7 1.0 12.8
BC= beta caroteneAT= alpha tocopherol
Às vezes, resultados de estudos epidemiológicos de prevenção primária desapontam...
Cumulative Incidence of Lung Cancer by Intervention Allocation (Albanes D, et al. JNCI 1996;88:1560-70)
Forest plot of the effect of group counselling on the incidence of smoking abstinence. Use of nicotine patch, bupropion, and notriptyline varied among studies (Motillo S, et al. Eur Heart J 2008 [Epub ahead of print Dec 24]
Interface between epidemiology and the
decision-making process
• Meta-Analysis
• Decision AnalysisEvaluation of community
effectiveness• Decision Analysis
• Cost-Effectiveness Analysis
(Pettiti DB. Meta-Analysis, Decision Analysis and Cost-Effectiveness Analysis. New
York, Oxford, Oxford University Press, 1994)
effectiveness
Interface between epidemiology and the
decision-making process
• Meta-Analysis
• Decision AnalysisEvaluation of community
effectiveness• Decision Analysis
• Cost-Effectiveness Analysis
(Pettiti DB. Meta-Analysis, Decision Analysis and Cost-Effectiveness Analysis. New
York, Oxford, Oxford University Press, 1994
effectiveness
Meta-Analysis
Summary of the
efficacy/effectiveness of the
intervention
Decision Analysis
Assessment of the relative value of the
programmatic options, based on their
community effectiveness (ideally determined
by meta-analysis)
Relations between meta-analysis, decision analysis and cost-
effectiveness analysis
intervention
Cost-effectiveness Analysis
Assessment of the cost of the program, based on the relative value
of the options
Decision Analysis: uses a quantitative approach to evaluate the relative value (effectiveness) of one or more interventions, programs or services.
Steps in Decision Analysis
• Identification and description of the problem
• Collection of the information needed to construct the decision tree (ideally by means of meta-analysis) decision tree (ideally by means of meta-analysis)
• Construction of a decision tree
• Analysis of the decision tree
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes
For those who tolerate the intervention, D has a lower
mortality than C
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes
For those who tolerate the interventions, D has a lower
mortality than C
Decision Node
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.10)
Mortality(0.20)
Mortality (0.50)
Mortality (0.50)
Mortality (0.05)
No(0.30)
Yes (0.70)
Tolerance to
intervention
High Social Class (0.10)
Low Social Class (0.90)
SC
High Social Class (0.10)
Low Social Class (0.90)
SC
Mortality (0.05)
Mortality (0.10)
Mortality (0.50)
Mortality (0.50)
Tolerance to
intervention
Yes (0.30)
No(0.70)
Example of decision tree with two chance nodes However, tolerance is better for Program C
Thus,C: better tolerance, higher mortalityD: worse tolerance, lower mortality
Table 2a – Program C: less efficacious but better drug tolerance (70%)
Tolerance? Joint probability of death
Yes 0.70 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
0.30 x 0.90 x 0.50= 0.135
Table 2b – Program D: more efficacious, but less drug tolerance (only 30%)
Tolerance? Joint probability of death
Yes 0.30 ×××× 0.10 ×××× 0.05= 0.0015
0.30 ×××× 0.90 ×××× 0.10= 0.027
No 0.70 ×××× 0.10 ×××× 0.50= 0.035
0.70 ×××× 0.90 ×××× 0.50= 0.315
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
0.70 ×××× 0.90 ×××× 0.50= 0.315
0.0015+ 0.027 + 0.035 + 0.315= 0.3785 or 37.85%
Conclude: Program D is more efficacious (i.e., those who tolerate the drug have a lower mortality than in Program C), but because tolerance to Program C is higher, its community effectiveness is higher.
Community effectiveness of C (compared with D)= {[37.85% - 28.30%] ÷ 37.85%} ×100= 25.2%
Sensitivity Analysis: a Tool for Public
Health Policy
• Approach to examine the changes in the output (results) of a given model resulting from varying certain model parameters (or assumptions) over certain model parameters (or assumptions) over a reasonable range (Szklo & Nieto. Epidemiology: Beyond the Basics.
2nd Edition, Jones & Bartlett, 2006).
Table 2a – Program C: less efficacious, but with better tolerance (70%)
Tolerance? Joint probability of death
Yes 0.7 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
Sensitivity Analysis: Assume that tolerance to the intervention in Program D is increased to 50%
0.30 x 0.90 x 0.50= 0.135
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
Table 2c – Program D with tolerance improved to 50%
Tolerance? Joint probability of death
Yes 0.50 ×××× 0.10 ×××× 0.05= 0.0025
0.50 ×××× 0.90 ×××× 0.10= 0.045
No 0.50 ×××× 0.10 ×××× 0.50= 0.025
Table 2a – Program C: less efficacious, but with better tolerance (70%)
Tolerance? Joint probability of death
Yes 0.7 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
Sensitivity Analysis: Assume that tolerance to the intervention in Program D is increased to 50%
0. 50 ×××× 0.90 ×××× 0.50= 0.225
0.0025 + 0.045 + 0.025 + 0.225= 0.2975 or 29.75%
0.30 x 0.90 x 0.50= 0.135
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
Community effectiveness of C (vis-a-vis D)= {[29.75% - 28.30%] ÷ 29.75%} × 100= 4.9%
Program C is still a bit more effective than Program D, but if the cost of D is lower, it may be cost-effective to implement Program D
(Before: 37.85%)
FIMFIM
Risk Factors for Brain Tumors in Subjects Aged <20 years: A Case-Control Study
(Gold et al, Am J Epidemiol 1979;109:309-19)
• Exploratory study of risk factors for brain tumors
• Subjects < 20 yrs old
• Cases: primary malignant brain tumors in Baltimore in 1965-75
• Normal controls: chosen from birth certificates on file, and matched on cases by sex, • Normal controls: chosen from birth certificates on file, and matched on cases by sex, date of birth (±1 year) and race
• Interviews with parents of children
• Exposed: children with birthweight equal or above the median (3629 g)
• Unexposed: children with birthweight below the median
• Odds ratio= 2.6
Exposed(1) Investigator
selects
Cohort (prospective) study
(2) Follow-up from present to future
INCIDENCEEXP
INCIDENCE
= RR
Unexposed
2009
selects present to future
2029
INCIDENCEUNEXP
Non-concurrent cohort (prospective) study (also
known as historical cohort study
Follow-up from past to present:
(2) Investigatorreconstructs cohort:
2009
(1) At presentinvestigator has
access to databasecreated in 1988
1989
Exposed
Unexposed
cohort:
“Follow-up”from ’89-’09
INCEXP
INCUNEXP
Exposed
Unexposed
2009
Follow-up from present to future
2029
CONCURRENT
INCEXP
INCUNEXP
NON-CONCURRENT
2009
Follow-upfrom ’89-’09
1989
Exposed
Unexposed
NON-CONCURRENT
INCEXP
INCUNEXP
Both studies startin year 2009
Exposed
Unexposed
2009
Follow-up from present to future
2029
CONCURRENT
INCEXP
INCUNEXP
NON-CONCURRENT
2009
Follow-upfrom ’89-’09
1989
Exposed
Unexposed
NON-CONCURRENT
INCEXP
INCUNEXP
In both studies, the initial selection (or classification) is based on the exposure, and the outcome (unknown
variable) is incidence
Example of Non-concurrent Prospective Study (Yeh et al, Am J Epidemiol 2001;153:749-56)
• Study subjects identified by investigators in 2000 as having been seen in a Clinic for Prevention of Deafness in Washington County, MD, from 1940-60, for elimination of nasopharyngeal lymphoid tissues.
• Exposed: Individuals who had nasopharyngeal radium • Exposed: Individuals who had nasopharyngeal radium treatment (n=808).
• Unexposed: Individuals who received other treatments (e.g., tonsillectomy) (n=1819).
• Outcome: Cancer Incidence
• Follow-up through 1995.
Design of Study Done by Yeh et al, Am J
Epidemiol 2001;153:749-56
FOLLOW-UP:35 YEARS
FOLLOW-UP THROUGH 1995
Adjustment for variable follow-up times: Rate per
person-years and Survival analysis
Study done in 2000
19601940
Reconstructionof cohort
1995
FOLLOW-UP: 55 YEARS
Survival analysis
Time
Relative Risk of Cancer Incidence (95% Confidence Interval) According to Exposure to Nasopharyngeal Radium Therapy,
Washington County, Maryland 1940-95
Cancer type
No. cases in exposed group (PY= 31,005)
No. cases in unexposed group
(PY= 65,502)
Adjusted Relative Risk (95% CI)
All neoplasms, 41 83 1.02 (0.7, 1.5)All neoplasms, except skin
41 83 1.02 (0.7, 1.5)
Oral cavity, pharynx, and thyroid
4 2 4.22 (0.38, 46.6)
(Yeh et al, Am J Epidemiol 2001;153:749-56)
Biologically plausible
800 200 500 500
80 100 50 250
180 300
18% 30%
Intervention No intervention
No. Deaths:
Mortality:
Absent, mortality = 10%
Present, mortality = 50%
Confounding variable:
One of the solutions to eliminate confounding: stratify
Mortality according to the intervention, stratified by the confounder
Confounding variable:
Intervention: N No. of deaths
Mortality
Present Yes 200 100 50.0%
No 500 250 50.0%
Absent Yes 800 80 10.0%
No 500 50 10.0%
Confounder
Exposure
Outcome
CONFOUNDING EFFECT
` and not in the causality pathway between ` and not in the causality pathway between exposure and outcome:
Confounder
Exposure
Outcome
Sensitivity Analysis: a Tool for Public
Health Policy
• Approach to examine the changes in the output (results) of a given model resulting from varying certain model parameters (or assumptions) over certain model parameters (or assumptions) over a reasonable range (Szklo & Nieto. Epidemiology: Beyond the Basics.
2nd Edition, Jones & Bartlett, 2006).
Table 2a – Program C: less efficacious, but with better tolerance (70%)
Tolerance? Joint probability of death
Yes 0.7 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
Sensitivity Analysis: Assume that tolerance to the intervention in Program D is increased to 50%
0.30 x 0.90 x 0.50= 0.135
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
Table 2c – Program D with tolerance improved to 50%
Tolerance? Joint probability of death
Yes 0.50 ×××× 0.10 ×××× 0.05= 0.0025
0.50 ×××× 0.90 ×××× 0.10= 0.045
No 0.50 ×××× 0.10 ×××× 0.50= 0.025
Table 2a – Program C: less efficacious, but with better tolerance (70%)
Tolerance? Joint probability of death
Yes 0.7 ×××× 0.10 ×××× 0.10= 0.007
0.70 × 0.90 × 0.20= 0.126
No 0.30 × 0.10 × 0.50= 0.015
Sensitivity Analysis: Assume that tolerance to the intervention in Program D is increased to 50%
0. 50 ×××× 0.90 ×××× 0.50= 0.225
0.0025 + 0.045 + 0.025 + 0.225= 0.2975 or 29.75%
0.30 x 0.90 x 0.50= 0.135
0.007 + 0.126 + 0.015 + 0.135= 0.283 or 28.30%
Community effectiveness of C (vis-a-vis D)= {[29.75% - 28.30%] ÷ 29.75%} × 100= 4.9%
Program C is still a bit more effective than Program D, but if the cost of D is lower, it may be cost-effective to implement Program D
(Before: 37.85%)
Decision Analysis: uses a quantitative approach to evaluate the relative value (effectiveness) of one or more interventions, programs or services.
Steps in Decision Analysis
• Identification and description of the problem
• Collection of the information needed to construct the decision tree (ideally by means of meta-analysis) decision tree (ideally by means of meta-analysis)
• Construction of a decision tree
• Analysis of the decision tree
• (Optional): Sensitivity analysis
DECISION TREE
• Decision node: under the investigator’s control
• Chance (or probability) node: not under the investigator’s control
Decision Node
Program AChance node
Outcome*
Outcome*
Outcome*
Example of a Decision Tree
High Social Class
Low Social Class
High Social Class
Program BChance node
Outcome*
Outcome*
*For example, mortality
Low Social Class
Decision Node
Program AChance node
High Social Class
Low Social Class
Mortality (0.20)
Mortality (0.40)
Example of Decision Tree (Probabilities)
(0.10)
(0.90)
Decision Node
Program B Chance node
High Social Class
Low Social Class
Mortality (0.90)
Mortality (0.90)
(0.10)
(0.90)
Note that the distribution of social class is same in both programs, as they are being considered for the same target population
Decision Node
Chance node
High Social ClassMortality (0.20)
Example of Decision Tree (Probabilities)
(0.10)
Program A
Decision Node
Program B Chance node
High Social Class
Low Social Class
Death (0.90)
Survival (0.10)
Death (0.90)
Survival (0.10)What is the joint probability of high social class (HSC) and mortality in program A?
Proportion HSC × Mort. A = 0.10 × 0.20= 0.02
Decision Node
Chance node
Low Social Class
Mortality (0.40)
Example of Decision Tree (Probabilities)
(0.90)
Program A
Decision Node
Program B Chance node
High Social Class
Low Social Class
Death (0.90)
Survival (0.10)
Death (0.90)
Survival (0.10)
(0.10)
(0.90)What is the joint probability of low social class (LSC) and mortality in program A?
Proportion LSC × Mort. A = 0.90 × 0.40= 0.36
Decision Node
Chance node
High Social Class
Low Social Class
Mortality (0.20)
Mortality (0.40)
Example of Decision Tree (Probabilities)
(0.10)
(0.90)
Program A
Decision Node
Program B Chance node
High Social Class
Low Social Class
Death (0.90)
Survival (0.10)
Death (0.90)
Survival (0.10)
(0.10)
(0.90)What is the joint mortality of all individuals in program A?
Mort. HSC + LSC= (0.10 × 0.02) + (0.90 × 0.40)= 0.02 + 0.36= 0.38
Decision Node
Chance node
High Social Class
Low Social Class
Mortality (0.20)
Mortality (0.40)
Example of Decision Tree (Probabilities)
(0.10)
(0.90)
Program A
Decision Node
Chance node
High Social Class
Low Social Class
Mortality (0.90)
Mortality (0.90)
(0.10)
(0.90)
Program B
Decision Tree: Program A versus Program B
Program A
Social Class Proportion in Each Social Class
Mortality in Each Social Class
Overall Mortality
High 0.10 0.20 0.10 × 0.20 = 0.02
Low 0.90 0.40 0.90 × 0.40 = 0.36
Total 0.02 + 0.36 = 0.38
Program BProgram B
Social Class Proportion in Each Social Class
Mortality in Each Social Class
Overall Mortality
High 0.10 0.90 0.10 × 0.90 = 0.09
Low 0.90 0.90 0.90 × 0.90 = 0.81
Total 0.09 + 0.81 = 0.90
Community effectiveness of A versus B*= [(0.90 – 0.38) / 0.90] × 100 = 57.8%
* That is, treating program A as the “experimental” program and program B as the “control” program
2. ETIOLOGYIdentify and assess possible causes of disease and risk factor burden
1. BURDEN OF ILLNESSDetermine health status
(mortality, prevalence, incidence, years of potential life lost, etc.
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC HEALTH POLICY
factor burden
3. COMMUNITY EFFECTIVENESSAssess benefit/harm ratio of potentially feasible interventions and estimate reduction of burden of illness if programs are effective
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness of options within and across programs
5. MONITORING OF PROGRAMOngoing monitoring using markers selected to indicate success
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
Other Cancer ControlsLung,
Non-tumor ControlsOther,
Non-cancer Controls
Case Control Case Control Case Control
Smokers 236(a) 666 (b) Smokers 236 124 Smokers 236 481
Non-122(c) 722 (d)
Non-122 110
Non-122 612
Odds ratio= (ad) / (bc)
Non-smokers
122(c) 722 (d)Non-
smokers122 110
Non-smokers
122 612
OR= (236 × 722) ÷ (666 × 122)= 2.10 OR = 1.72 OR = 2.46
95% CI: 1.6-2.7 95% CI: 1.2-2.4 95% CI: 1.9-3.2
Levin ML, Goldstein H and Gerhardt PR: Cancer and Tobacco Smoking. A Preliminary Report. JAMA, 143:336-338, 1950.
Objectives of Epidemiology
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons (e.g., age, gender), time and place;
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive strategies;
• Translate epidemiologic findings into public health policies
(INCA-MS Estimativas 2006 – Incidencia de Cancer no Brasil)
Objectives of Epidemiology
• Describe the magnitude of the disease burden in the population
• Examine the distribution of the disease in the population using vital statistics data according to factors related to persons (e.g., age, gender), time and place;
• Investigate the etiology (risk factors) of disease;
• Assess effectiveness of preventive strategies.
Decision Tree with Multiple Chance Nodes
Decision tree for the treatment of high blood pressure based on 52 hypertensive patients. Values besides each outcome health state are median and inter-quartile range. CVE, cardiovascular event (newly diagnosed angina,
myocardial infarction, coronary heart disease, stroke or transient ischemic attack) (Montgomery AA, et al. Shared decision making in hypertension. Family Practice 2001;18:309-313).
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
assess efficacy of primary and secondary prevention
strategies
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention
strategies
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention strategies
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention
strategies
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
4. COST-EFFECTIVENESSDetermine relationships
between costs and effectiveness across programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention
strategies
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)
Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention
strategies
1. BURDEN OF ILLNESSDetermine health status
(mortality, incidence, etc.)
6. REASSESSMENTReassessment of magnitude of burden of illness or risk
factor
INTERFACE BETWEEN EPIDEMIOLOGY AND PUBLIC
HEALTH POLICY
INTERFACE BETWEEN EPIDEMIOLOGY AND CANCER CONTROL POLICY
2. ETIOLOGY AND EFFICACY
Identify risk factors and assess efficacy of primary
4. COST-EFFECTIVENESSDetermine relationships between costs and effectiveness across
programs
5. MONITORING OF PROGRAM (SURVEILLANCE)Ongoing monitoring
HEALTH POLICY
Modified from: Tugwell et al, J Chron Dis 38(4)
3. COMMUNITY EFFECTIVENESSAssess effectiveness in the target
community
assess efficacy of primary and secondary prevention
strategies
Aplicação da politica: planejamento
• Evidências• Obstáculos
Políticas baseadas em evidências
• Colaboração Cochrane
• Outras fontes (meta-análises publicadas em
Revisões sistemáticas
Custo-efetividade
Análise de sensibilidade
Vigilância
• Ensaios aleatorizados
• Estudos de coorte
• Estudos de casos e
Aquisição de evidências científicas
Magnitude das DCNT
Processo de Implementação de Politicas de Controle do Câncer Baseadas em Evidências
• Obstáculos
• Avaliação de níveis de evidência
• Seleção de opções programáticas (análise de decisão)
• Recomendações
publicadas em revistas)
• Revisões Sistemáticas e meta-análisesrealizadas de
novo
• Estudos conduzidos de
novo:
• Estudos de casos e controles
• Estudos de séries temporais
• Estudos de processo e estrutura
: análise de tendências
Tradução de conhecimentos(Modificado de Dickersin K)
• Hipóteses causais
• Avaliação de intervenções, políticas e programas
• Avaliação de niveis epidêmicos (inclusive “clusters)
Cumulative incidence
Prostate Cancer Deaths in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial
(Andriole GL et al, New Eng J Med 2009;360:1310-9)
Cumulative incidence
Prostate Cancer Deaths in the European Randomized Study of Screening for Prostate Cancer (Schroder FH, et al. New Eng J Med 2009;360:1320-8)
(Holder AM, Gonzalez-Angulo AM, Chen H, et al. High stearoyl-CoA desaturase 1 expression is associated with shorter survival in breast cancer patients. Breast Cancer Res Treat [epubl, Dec 2012])
Assumption Justifying a Screening Program
• In the absence of intervention, all or most cases in a pre-clinical phase progress to the clinical phase (may not be true for certain cancers; e.g., prostate)
Detecção baseada em sintomas ou
Momento em que a detecção
precoce se torna possivel
Início da exposição a fatores de risco
Início da enfermidade
sintomas ou sinais que ocorrem no início da fase clínica,
possivel
Fase pré-clínica detectável (FPCD)
Fase pré-clínica não detectável
Cura ou Morte
Fase clinica
(INSERT DATA FROM BREAST CANCER (Bleyer A, Welch HG. Effect of three decades of screening mammography on breast cancer incidence. New Eng J Med 2012;367:21)
• Proteção contra a fumaça do tabaco e proibição de fumo em ambientes públicos
• Alertas com relação aos perigos do uso de tabaco• Implementação da proibição de propaganda, promoção e patrocínio
de eventos por tabaco• Aumento de impostos de produtos de tabaco• Restrição de acesso a álcool em negócios• Implementação de proibição de propaganda de bebidas alcólicas• Aumento de impostos de bebidas alcólicas• Redução de consumo de sal e quantidade de sal em alimentos
Algumas atividades de prevenção primáriacusto-efetivas sugeridas por estudos epidemiologicos (OMS)
• Redução de consumo de sal e quantidade de sal em alimentos processados
• Substituição de gorduras “trans” por gorduras poli-não saturadas• Conscientização do público sobre importância de dieta saudável e
atividade física, inclusive através de meios de comunicação • Controle de glicemia em pacientes com 30 anos ou menos com
diabetes se o risco de eventos agudos cardiovasculares for ≥30% nos próximos 10 anos
• Aspirina para prevenção de infarto agudo do miocárdio• Mamografia a cada 2 anos para mulheres de 50 a 70 anos• Detecção precoce de câncer colo-retal
• Proteção contra a fumaça do tabaco e proibição de fumo em ambientes públicos
• Alertas com relação aos perigos do uso de tabaco• Implementação da proibição de propaganda, promoção e patrocínio
de eventos por tabaco• Aumento de impostos de produtos de tabaco• Restrição de acesso a álcool em negócios• Implementação de proibição de propaganda de bebidas alcólicas• Aumento de impostos de bebidas alcólicas• Redução de consumo de sal e quantidade de sal em alimentos
Algumas atividades de prevenção primáriacusto-efetivas sugeridas por estudos epidemiologicos (OMS)
• Redução de consumo de sal e quantidade de sal em alimentos processados
• Substituição de gorduras “trans” por gorduras poli-não saturadas• Conscientização do público sobre importância de dieta saudável e
atividade física, inclusive através de meios de comunicação • Controle de glicemia em pacientes com 30 anos ou menos com
diabetes se o risco de eventos agudos cardiovasculares for ≥30% nos próximos 10 anos
• Aspirina para prevenção de infarto agudo do miocárdio• Mamografia a cada 2 anos para mulheres de 50 a 70 anos• Detecção precoce de câncer colo-retal
• Proteção contra a fumaça do tabaco e proibição de fumo em ambientes públicos
• Alertas com relação aos perigos do uso de tabaco• Implementação da proibição de propaganda, promoção e patrocínio
de eventos por tabaco• Aumento de impostos de produtos de tabaco• Restrição de acesso a álcool em negócios• Implementação de proibição de propaganda de bebidas alcólicas• Aumento de impostos de bebidas alcólicas• Redução de consumo de sal e quantidade de sal em alimentos
Algumas atividades de prevenção primáriacusto-efetivas sugeridas por estudos epidemiologicos (OMS)
• Redução de consumo de sal e quantidade de sal em alimentos processados
• Substituição de gorduras “trans” por gorduras poli-não saturadas• Conscientização do público sobre importância de dieta saudável e
atividade física, inclusive através de meios de comunicação • Controle de glicemia em pacientes com 30 anos ou menos com
diabetes se o risco de eventos agudos cardiovasculares for ≥30% nos próximos 10 anos
• Aspirina para prevenção de infarto agudo do miocárdio• Mamografia a cada 2 anos para mulheres de 50 a 70 anos• Detecção precoce de câncer colo-retal