epidemiology
TRANSCRIPT
Epidemiology
EPIDEMIOLOGYEPI DEMOS LOGOS
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UPON POPULATION STUDY
The foundation of epidemiology was laid (place) in the 19th century. The epidemiology has grown rapidly during the three decades.
Definition: There are many definitions put by the epidemiologists of time such as: 1. That branch of medical science which treats of epidemics (Parkin 1873).2. The science of mass phenomenon of infectious disease (Frost 1927). 3. The study of disease, any disease as mass phenomenon (Green Wood 1934).
4. The study of the distribution and determinants of disease frequency in man (Mac Mohan 1960).
BUTThe agreed and final definition up to date is: The study of distribution and determinants of health related states or events in specified human population and its application to the control of health problem (by: John.M.Last in 1988).
Key Words in Definition:1. Distribution
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By Time, Place Person. Cause, Risk Factors. Public Health. Information For.
2. Determinants = 3. Population
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4. Application
5. Health events = Deaths, Births, Utilization Services, Evaluation of Health Service Activities. Although there is no single definition to which all epidemiologists agree, but at least three components are common among them: 1. Study of disease frequency.COMPILED BY: BHERU LAL Page 1
Epidemiology 2. Study of distribution. 3. Study of determinants.
Modern epidemiology include the study of health related events and facts of life occurring in human population and to measure their impact. Epidemiology like public health is more concern with well being of society as whole than with well being of individual.
Medicine versus EpidemiologyDifference 1. Focus 2. Main goal 3. Questions Clinical Medicine Individual Diagnosis treatment Population Prevention control Epidemiology
What is the wrong with the What are leading causes of deaths or patient? & what treatment is disability in the population? & what can be suitable? done to reduce/prevent/control.
CHARACTERISTICS / FEATURES OF EPIDEMIOLOGY It is a quantitative science. It is an applied science. Its methods are generally observational. Its focus is the group or community of persons. Its methods are systematic and orderly.
CORE FUNCTIONS OF EPIDEMIOLOGY 1. Public health surveillance. 2. Investigation. 3. Data analysis. 4. Evaluation 5. Communication 6. Management and treatment.
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Epidemiology
USES OF EPIDEMIOLOGY 1. Determine the magnitude and trend of diseases. 2. Identify the etiology or cause of disease. 3. Determine the mode of transmission. 4. Identify the risk factor. 5. Determine the role of environment. 6. Evaluate the impact of the control measures. FUNCTIONS OF THE NURS IN EPIDEMIOLOGY Maintains surveillance of the occurrence of notifiable disease Coordinates with other members of the health team during a disease outbreak Participates in case finding and collection of laboratory specimens Isolates cases of communicable disease Renders nursing care teaches and supervises giving of care Performs and teach household members methods concurrent and terminal disinfection. Gives health teaching to prevent further spread of disease to individuals and families Follow up cases and contacts Organize, coordinate and conduct community health education campaign/ meetings Refers cases when necessary Coordinates with other concerned community agencies Accomplishes and keeps records and reports and submits to proper office/ agency
Definition of health
Health is a state of complete physical, mental and social well being and not merely absence of disease or infirmity. Include the ability to lead a socially and economically productive life.
Spectrum of Health (spectrum= range, field, scale, variety) Health and disease lie very close. There is no single cut off point.Page 3
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Epidemiology
The lowest point on the health-disease is death and the highest point is the positive health. Health fluctuates within a range of optimum well being to various level of dysfunction even total dysfunction like death. The transition from optimum health to the ill health is often gradual. The spectral concept of health emphasizes that the health of the individual is not static, it is dynamic phenomenon and a process of continues change. The maximum health of today can be minimum health of tomorrow. Health is a state not to be attained once and for all, but ever to be renewed. There are degrees or levels of health Like: Positive health better health freedom from sickness mild sickness sever sickness DEATH. unrecognized sickness
CONCEPT OF DISEASE:
Condition in which body health is impaired. Departure from a state of health. An alteration of human body interrupting the performance of vital functions. Condition of the body or some part or organ of the body in which the functions are disrupted. Maladjustment of the human organism to the environment. Social phenomenon, occurring in all societies. Disease is said to be just apposite (relevant/appropriate) to health. The WHO has defined health not disease. This is because disease many shades ranging from unapparent (sub clinical) to sever illness. Some diseases come acutely and some diseases insidiously. The term disease means without ease (uneasiness). Illness refers not only to the presence of specific disease, but also to the individuals perceptions and behavior in response to the disease. Sickness refers to social dysfunction. Disease is a physiological/ psychological dysfunction.Page 4
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Epidemiology
Illness is a subjective state of the person who feels aware of not being well. Sickness is a state of social dysfunction. In short the definition of disease is yet to be found. Definition that is satisfactory; acceptable to the epidemiologist, clinician, sociologist and the statistician. The causative factors of disease may be classified as Agent, Host and Environment. These three factors are referred as Epidemiological Triad. (Triad= harmony, musical tones). The only presence of host, agent and favorable environment factors are not sufficient to cause the disease.
SPECTRUM OF DISEASE The graphic representation of variation in the manifestation of disease. The spectrum of light, color varies from one end to the other. Difficult to determine where one color ends and other begins: o Sub clinical. o Illness mild, moderate to severe. o Fatal illness. The sequence of the events in the spectrum of diseases can be interrupted by early diagnosis and treatment of by preventive measures.
NATURAL HISTORY OF DISEASE
Disease results from complex interaction between men, an agent, and the environment. The natural history of disease is a key concept in epidemiology. It indicates the way in which a disease starts and ends. The natural history of disease is best established by cohort studies. Natural history of disease is consists of two phases:
Pre-pathogenesis at first man is exposed to a predisposing factor or stimuli which would cause the disequilibrium. Pathogenesis starts once a host is found to succumb (give way, yield, submit) the disease.Page 5
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EPIDEMIOLOGIC TRIAD OF A DISEASEIt is a triad of interacting factors related to host, agent and environment and explain the disease process. Host
Agent It determines:
Environment
1-Exposure of man to the risk of morbidity. 2-Characteristic features and pattern of disease. 3-Endemicity (existence and perpetuation) of a disease in the involved community. 1-HOST: Refers to human or nonhuman and specifically the particular person or group of people susceptible to illness. Host factors include: age, sex, marital status, race, specific immunity, genetic predisposition, occupation, education, religion, culture, lifestyle, health status, behaviors. All the host factors are called intrinsic factors 2-AGENT: The agent is the direct cause of disease without which a specific disease cannot occur. It may be exogenous (from pollution of the environmentphysical, chemical or biological) or endogenous (e.g. psychological and mental disorders). So, an agent could be: -Biologic (microorganisms) -Chemical (toxins, drugs, tobacco) -Physical (fire, radiation, trauma) -Nutritional (lack of, excess or imbalance)
Idiopathic diseases: Agents of diseases are sometimes not precisely known e.g. cancers, essential hypertension
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Risk factors: are not direct causal agents of diseases, but they increase susceptibility of the at-risk individuals or groups to disease (and so show significantly more incidence of that disease).
3-ENVIRONMENT: It is the medium (milieu) where man lives: It includes all what is external to the agent and host.
It is classified into three classes: 1. The physical environment (weather, light, air quality, water, radiation, pressure [altitude], noise, chemicals .) 2. The biologic (infectious agents of disease, reservoir of infection, vehicles of transmission as mosquitoes & flies, and modes of propagation as air and water). 3. Socio-economic (overall economic and political organizations of a society where individuals live). All the environmental factors are called extrinsic factors Human environment must be sanitary: Fulfills standard sanitary requirements. Free of vectors of diseases, rodents and pollution. LEVELS OF PREVENTION Primary Preventiona) Primary this is accomplished in the pre-pathogenesis period of the natural history of
disease, by measures designed to promote general optimum health or by specific protection of man against disease agents or the establishment of barriers against agents in the environment. Health Promotion Specific Protection
Secondary Preventiona) Secondary as soon as the disease process is detectable early pathogenesis, secondary
prevention may be accomplished by: Early Diagnosis and Prompt Treatment o To prevent spread to others if the disease is communicable o To cure or arrest the disease process in order to prevent complications o To prevent prolonged disabilityCOMPILED BY: BHERU LAL Page 7
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Tertiary Prevention a) The retraining, reeducation, and rehabilitation of the patient who has already incurred disabilityb) Tertiary as the process of pathogenesis progresses, it is still possible to accomplish
prevention by what might be termed as corrective therapy or tertiary, which usually consist of: Disability Limitation Rehabilitation
DESCRIPTIVE EPIDEMIOLOGY: Person, Place and Time Person Age Sex Death rates are higher for males than females, but morbidity rates are higher for females In utero and neonatal death rates are also higher for malesPage 8
The study of the amount and distribution of disease within a population by person, place and time. WHO (person) is affected? WHERE (place) do the cases occur? WHEN (time) does it happen?
Age, sex, ethnic group, social class, occupation exposures, marital status, family variables, etc.
The most important determinant among the personal variables Death rate is fairly high in infancy Lowest point is between 5-14 years old Doubling in rate from 40 and every decade of life Chronic conditions tend to increase with age whereas the relation of age to acute infectious diseases is less consistent Age is related to the frequency and severity of infectious diseases High rate of injury in particular age group
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The higher death rates for males throughout life may be due to sex-linked inheritance, differences in hormonal balance, environment or habit patterns The higher mortality rate for men are not paralleled by higher rates of illness Women have more episodes of illness and more physician contacts than men have Rate of attempted suicide is higher in women but completed suicides are more common in men Toxic shock syndrome o Irritant tampons
Possible explanations for relatively high morbidity and low mortality in women: o Women seek medical care more freely and perhaps at an earlier age of disease
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What is Data?Data is a collection of facts, such as values or measurements. It can be numbers, words, measurements, observations or even just descriptions of things. Qualitative vs QuantitativeData can be qualitative or quantitative. Qualitative data is descriptive information (it describes something) Quantitative data is numerical information (numbers).
And Quantitativ e data can also be Discrete or Continuous: Discrete data can only take certain values (like whole numbers) Continuous data can take any value (within a range)
Put simply: Discrete data is counted, Continuous data is measured
Example: What do we know about Arrow the Dog? Qualitative:
He is brown and black He has long hair He has lots of energy Quantitative:
Discrete: He has 4 legs He has 2 brothers Continuous: He weighs 25.5 kg He is 565 mm tall
To help you remember think "Quantitative is about Quantity"
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Discrete and Continuous DataData can be Descriptive (like "high" or "fast") or Numerical (numbers). And Numerical Data can be Discrete or Continuous:
Discrete data is counted, Continuous data is measured Discrete DataDiscrete Data can only take certain values. Example: the number of students in a class (you can't have half a student).
Continuous Data Continuous Data is data that can take any value (within a range) Examples:
A person's height: could be any value (within the range of human heights), not just certain fixed heights, Time in a race: you could even measure it to fractions of a second, A dog's weight, The length of a leaf, Lots more!
COLLECTINGData can be collected in many ways. The simplest way is direct observation. Example: you want to find how many cars pass by a certain point on a road in a 10-minute interval. So: simply stand at that point on the road, and count the cars that pass by in that interval. You collect data by doing a Survey.
Census or SampleA Census is when you collect data for every member of the group (the whole "population"). A Sample is when you collect data just for selected members of the group. Example: there are 120 people in your local football club. You can ask everyone (all 120) what their age is. That is a census.
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Epidemiology Or you could just choose the people that are there this afternoon. That is a sample. A census is accurate, but hard to do. A sample is not as accurate, but may be good enough, and is a lot easier.
LanguageData or Datum?Strictly speaking, the word data is in the plural (the singular form is datum). However, the word is often used as if it is a singular noun. So we commonly say "the data is available" rather than the more correct way "the data areavailable".
SOURCES OF DATA : Two types of Data according to Source: Primary Data - obtained by the investigator o Example: interviews, physical examination, laboratory exams o More accurate and up-to-date Secondary Data - data actually gathered by other individuals or agencies o Example: published reports, clinical/hospital records, census o more readily available but incomplete o confidentiality of information Surveillance In most health departments, routinely collected statistics provide the key data for monitoring morbidity and mortality trends. Surveillance System includes a functional capacity for data collection, analysis and dissemination linked to public health programs. Epidemiologic Surveillance Has been defined by the Centers for Disease Control (CDC) as the ongoing systematic collection, analysis and interpretation of health data essential to the planning, implementation and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know. Specific Data that are Useful in Epidemiologic Studies 1. Data on vital events o Birth, death, marriages, divorces, adoptions, total births/deaths, deaths by specific causes, mortality rate, case fatality rate, etc. 2. Diseases statistics o prevalence and incidence of specific diseases
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3. Data on physiologic or pathologic conditions o Prenatal Hgb levels, blood sugar levels among diabetics, BP readings 4. Statistics on Health Resources and Services o Number of hospital beds, vaccine vials consumed, number of health center staff 5. Statistics pertaining to the environment o Number of households with sanitary water source, number of snail breeding places, amount of pollution in the air, level of noise in the factory, workers protective gears 6. Demographic data o Total number of population, age groups, gender, rural-urban residence, occupation, income 7. Socio-cultural data o knowledge, attitude, practices of people regarding health 10 Key Sources of Data for Surveillance Systems Designed by the WHO Mortality registration Morbidity reporting Epidemic reporting Laboratory investigation Individual case investigations Epidemic field investigations Surveys Animal-reservoir and vector distribution studies Biologic and drug utilizations Knowledge of the population and the environment Other Sources of Surveillance Data Hospital and medical care statistics Panels of cooperating physicians Public health laboratory reports Absenteeism from work or school Telephone and household surveys Newspaper and news broadcasting reports Locally, data may be available from: Department of Health National Institutes of Health Medical Specialty Societies National Congenital Defects Registry Newborn Screening Program Specialty Hospitals National Census and Statistics Office
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BASIC MEASUREMENTS IN EPIDEMIOLOGYMeasuring events (disease events or health events) is at the heart of epidemiology. If one can not quantify, one can not do epidemiological research. Epidemiology is a quantitative science. Thus we use the methods of "counting" diseases or deaths to describe the frequency with which diseases occur. The simplest method to express frequency is to count the number of persons in the group studies who have a particular disease or a particular characteristic BUT the number of cases of a disease may vary from place to place according to the number of people in each place. Thus, we have to relate number of cases of a disease to the population from which these cases come. The key in epidemiology is relating the frequency (the numerator) to an appropriate population (the denominator). This is done by computing rates, ratios and proportions. So, we express disease frequency not as absolute number BUT a related number.
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1-RatioRatio is the relationship between two numbers (one is divided by the other). It does not relate to a particular time. Those included in the numerator are not included in the denominator. In ratios, Numerator represents the number of events that meet a specific criterion. Denominator represents the number of events that meet a different criterion.
Examples:
Sex Ratio =
Number of males
Number of females
Risk Ratio = Risk of disease in one group (exposed)
Risk of disease in another group (unexposed)
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2-ProportionA special ratio where a number of individuals within a defined group with the outcome of interest (numerator) is divided by the number of individuals enumerated in the population (denominator). The numerator is a subset of the denominator = a/a+b It may be expressed as a number between 0 and 1 (0.1, 0.2, 0.35 .), OR as a percentage (X 100).
Examples: -Proportion of male births =
Number of male births Total number of births
-Proportion of persons with a specific disease (usually termed: prevalence) =
Number of persons with a specific disease Total population being considered
Example: distribution of cases of type I diabetes: Age 0 - 4 = 70 cases Age 5 - 9 = 73 cases Age 10-14 = 75 cases Total 218
70 = 0.32 or 32% of all children who developed 70+73+75 diabetes were less than age of 5.
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3-RateIt is a special ratio (all rates are ratios but not all ratios are rates), where a number of individuals within a defined group with the outcome of interest (numerator) is divided by the number of individuals enumerated in the population (denominator) per unit length of time. i.e. rate is the number of persons (diseased or dead) per unit of population per unit of time. The numerator is a subset of the denominator = a/a+b
Rate = Number of events (disease or death) in a specified period xK
Number of population at risk of these events in the same period **K is a constant used to get a whole number to avoid fraction. The rate is multiplied by 1,000, 10,000 or 100,000 for ease of interpretation.
RATES, RATIOS, PROPORTIONSCompiled by: BHERU LAL Page 17
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Three general classes of mathematical parameters. Often used to relate the number of cases of a disease or health outcome to the size of the source population in which they occurred.
Hypothetical data on the frequency of Hepatitis in two cities Location City A City B New cases 62 35 Year 2002 2002 Population 25,000 7,000
Annual occurrence of Hepatitis: City A: 62 / 25,000 = 2.5 per 1,000 City B: 35 / 7,000 = 5.0 per 1,000
RATIO
Obtained by dividing one quantity by another. These quantities may be related or may be totally independent. Usually expressed as:x 10 n y
Example: Number of stillbirths per thousand live births.# stillbirth s 1000 # live births
General term that includes Rates and Proportions.
Example: A foodborne epidemic occurred in an elementary school. The attack rate in the first grade was 24% while the attack rate in the second grade was 16%. Compare these two attack rates.24% 1.5 = 16% 1
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PROPORTIONA ratio in which the numerator is included in the denominator. Expressed as:x 10 n y
where, 10n is often 100. Example: The number of fetal deaths out of the total number of births.# of fetal deaths 100 live births + fetal deaths
Answer often read as a percent.
Example: 500 people attended a company picnic and 50 became ill with acute enteric disease. Calculate the proportion of ill persons.50 100 =10.0% 500
RATE
A measure of how quickly something of interest happens. Expressed as:x 10 n y
Example: The number of new cases of Parkinsons disease which develops per 1,000 personyears of follow-up.# of new cases of Parkinson' s disease 1000 Total time disease - free subjects observed
Time, place and population must be specified for each type of rate.
CONCEPT OF NUMERATOR, DENOMINATOR
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NUMERATOR Number of time an event occurs in population at particular time. The nominator is the component of denominator in calculating rate and proportion but in ration. DENOMINATOR: Numerator has little meaning without denominator. The epidemiologist is always in search of appropriate denominator for calculating RATE. Denominator may be related to the population or may be related with total events. RELATED WITH POPULATION: Mid year population. Population at risk (in accident rate all who are at risk. but in food poising and general fertility rate, the denominator will be all those who ate food and all women of CBA group.) Person-time (In some study number of people or involved for certain time.) Sub-group of population, e.g.; age, sex, occupation, social class etc.) RELATED TO THE EVENTS: The denominator is related with total events e.g.: IMR, CFR, in some cases number of accident per 1000 vehicle is useful than number of people.
ANALYTIC EPIDEMIOLOGY Definition
Study the determinants of disease or reasons for low and high frequency in specific groups Employs epidemiologic methods: Definition of the problem Appraisal of existing facts Formulation of hypothesis Testing of hypothesis Conclusion and practical application
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Principal Uses Community diagnosis Investigation of epidemics Determination of disease etiology Evaluation of community intervention and programs
EPIDEMICS Definition
The occurrence of any number of cases of a disease clearly in excess of the normal expectancy or what usually prevails.
Steps in the Investigation of Epidemics Definition of the problem verify the diagnosis establish existence of an epidemic Appraisal of existing facts Characterize the distribution of cases by person, place and time. Formulation of hypothesis as to source of infection, mode of transmission, factors that may have given rise to the epidemic
Testing of hypothesis conduct an epidemiological investigation (case control)
==Conclusion and recommendations for control and prevention ANALYTIC STUDIES Types
Case-control Studies o cases (with disease) and controls (no disease) are selected from a chosen population
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o
both are questioned or records are reviewed about presence or absence of a suspected cause/risk factor in the past
Uses
to test risk factors preferred if disease is rare preferred if several factors are associated with disease of interest
Requirements for valid results Cases must be representative of all those with disease and clearly defined. Controls must be representative of all those without the disease and come from same community or source as the cases. Analysis Odds Ratio (OR)
proportion of those with history of exposure to the factor among the cases (a/a+c) is compared to those with history of exposure (b/b+d) to the factor among the controls OR = ad/bc
ANALYSIS OF CASE CONTROL STUDIES Outcome (Disease)+ Exposure (Factor) c a+c d b+d + a b
* Statistical association between factor and outcome exists if (a/a+c) (b/b+d) * Association is probably causal, if OR > 1 Advantages more economical smaller sample size required suitable for rare diseases suitable for diseases associated with multiple exposures
DisadvantagesCompiled by: BHERU LAL Page 22
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more susceptible to bias of recall estimate of risk is indirect controls more difficult to assemble temporal relationship between factor and outcome cannot be ascertained COHORT STUDIES
groups of subjects are chosen on the basis of having been exposed to a factor or not groups are followed up to identify those who develop the disease or outcome
Uses to test prognostic factors to directly measure risk of development of disease or outcome provide more definitive information about disease etiology preferred for study of rare exposures
Requirement for valid results Similarity of comparison groups
Types a. Concurrent Subjects are free of disease or outcome of interest at the time of initiation of the study. Investigator follows-up the groups or cohorts from exposure to appearance of disease or outcome. b. Non-Concurrent Subjects who are free of the disease or outcome of interest at some point in the past
are identified in terms of their exposure level. Disease or outcome status is determined through existing records.
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At the time the study is conducted, the specified follow-up period has elapsed. Analysis
Relative Risk or Risk Ratio(RR)
proportion of subjects with the disease or outcome among the exposed (a/a+b) is compared to proportion of subjects with the disease or outcome among the unexposed (c/c+d)
RR = a/a+b c/c+d ANALYSIS OF COHORT STUDIES Outcome (Disease) + + Exposure (Factor) c a+c d b+d a b
* Statistical association between factor and outcome exists if (a/a+b) (c/c+d) * Association is probably causal, if RR > 1
Attributable Risk (AR) estimate of the amount of risk that is attributable to the risk factor AR = a/(a+b) - c/(c+d) Advantages
provides direct estimate of risk temporality can be ascertained (for concurrent studies) less biases of recall and observation allows for determination of population-based rates
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controls easier to assemble variations in exposure can be followed-up unsuspected effects of the exposure may be observed
Disadvantages more expensive follow-up period may be long high attrition rate large sample size required change in exposure rates over long periods of time
COMPARISON OF CHARACTERISTICS OF CASE CONTROL AND COHORT STUDIES
Case Control Starting population Control Group Information Sought Principal bias Diseased group Non-diseased Frequency of exposure to risk factor Knowledge of disease influences report of exposure
Cohort Exposed group Unexposed Disease rate Knowledge of exposure influences diagnosis
EXPERIMENTAL STUDIES Requirement for validity: complete comparability of comparison groups Types Clinical Trial - Randomized Controlled Trial (RCT) investigator randomly places the subjects to one of the intervention groups ex. drug or surgical trials used if strong evidence for association already exists Analysis
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comparison of disease or outcome rate in experimental (P1) = (a/a+c) and control groups (P2) = (b/b+d) Therapeutic / Preventive Measure + -
+ Disease/ Outcome -
a
b
c a+c
d b+d
Protective Value = P2 P1 P2
Advantage Provide the strongest evidence for testing hypothesis Limitation ethical issues, especially for clinical trials
Measures of morbidity: Morbidity is a departure subjective or objective, from state of physiological well-being. o Disease. o Injury. o Disability. Morbidity may be refer few terms. o Number of person who are ill. o Period of illness. Three aspects of morbidity are measured by morbidity rates or morbidity ratios.Page 26
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o Frequency. o Distribution. o Severity. Disease frequency is measured by: o Incidence rate. o Prevalence rate. INCIDENCE RATE
The number of new cases occurring in a defined population during specified period of time. Incidence measures the rate at which new cases occurring in a population. Incidence is not influenced by the duration of the disease. The use of incidence is usually restricted to acute condition.
Formula: Incidence Rate: No: of new cases of specific disease during a given time period x 1000 Population at risk Example: If there had been 500 new cases of an illness in a population of 30,000 in a year, the incidence rate would be: = 500/30,000 x 1000 = 16.7 per 1000 per year.
Formulas and Definitions for Calculating RatesPercent = __number of events__ X 100 total events
EXAMPLE: Percent of people in County A over 50 in 2000 = _number of people in County A over 50_ X 100 total population of County A
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numerator= number of people in County A over 50 = 150 denominator = total population of County A = 3,456 constant = 100 time period = 2000
Percent of people in County A over 50 in 2000 = _150_ X 100 = 4.3% 3,456
Crude Birth Rate (CBR) = ___number of live births during time period___ X 1,000 total population at mid-point of time period
EXAMPLE: CBR for NM 2000 = __number of NM live births in 2000__ X 1,000 population of NM in 2000
numerator = number of NM live births in 2000 = 27,206 denominator = population of NM in 2000 = 1,819,046 constant = 1,000 time period = 2000
CBR for NM 2000 = __27,206__ X 1,000 = 14.9/ 1,000 population 1,819,046
Fertility Rate = __number of live births during time period__ X 1,000 total population of females age 15-44 at mid-point of time period
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EXAMPLE: Fertility Rate for Los Alamos County 2001 = __number of live births in Los Alamos in 2001__ X 1,000 population of Los Alamos females 15-44 in 2001
numerator = number of live births in Los Alamos in 2001 = 169 denominator = population of Los Alamos females 15-44 in 2001= 3,105 constant = 1,000 time period = 2001
Fertility Rate for Los Alamos County 2001 = __169__ X 1,000 = 54.4 /1,000 females ages 1544 3,105
Crude Death Rate (CDR) =___number of deaths during time period____ X 100,000 total population at mid-point of time period EXAMPLE: CDR for Grant County 2001 = __number of deaths in Grant County in 2001_ X 100,000 total population Grant County 2001
numerator = number of deaths in Grant County in 2001 = 301 denominator = total population Grant County 2001 = 30,726 constant = 100,000 time period = 2001
CDR for Grant County 2001 = __301__ X 100,000 = 979.6/ 100,000 population 30,726
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Age-specific Death Rate = __number of deaths among persons of a given age group__ X 100,000 population of persons in given age group at mid-point of time period EXAMPLE: Death Rate for ages 45-54 in =2001__ X 100,000 number of deaths among ages 45-54 in Bernalillo County Bernalillo County 2001_in
number of persons ages 45-54 in Bernalillo County in 2001
numerator = number of deaths among ages 45-54 in Bernalillo County in 2001 = 335 denominator = number of persons ages 45-54 in Bernalillo County in 2001= 80,689 constant = 100,000 time period = 2001
Death Rate for ages 45-54 in = __335__ X 100,000 = 552/ 100,000 persons ages 45-54 Bernalillo County 2001 60,689
Cause - specific Death Rate=_number of deaths from a specified cause during time period_X100,000 total population at mid-point of time period EXAMPLE: Heart Disease Death Rate for NM 2001 = _number of deaths from heart disease in NM_ X 100,000 population of NM 2001
numerator = number of deaths from heart disease in NM = 3,339 denominator = population of NM 2001 = 1830935
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constant = 100,000 time period = 2001
Heart Disease Death Rate for NM 2001 = __3,339__ X 100,000 = 182.3/ 100,000 population 1,830,935
Infant Mortality Rate (IMR) = __number of infant deaths during time period__ X 1,000 number of live births during time period EXAMPLE: IMR for Bernalillo County 2001 =__number infant deaths Bernalillo County 2001_ X 1,000 number of live births Bernalillo County 2001 numerator = number infant deaths Bernalillo County 2001= 50 denominator = number of live births Bernalillo County 2001 = 8,357 constant = 1,000 time period = 2001 IMR for Bernalillo County 2001 = __50 __ X 1,000 = 5.9/ 1,000 live births 8,357
Neonatal Mortality Rate = number of deaths to children