annual arizona conference for tribal bccedp collaboration, flagstaff, az

Inter Tribal Council of Arizona, Inc.

Tribal Epidemiology Center

TEC Director

Jamie Ritchey, MPH, PhD

August 7, 2012

• Overview of Inter Tribal Council of

Arizona (ITCA), Inc. Tribal Epidemiology

Center (TEC)

• Epidemiology Basics

• Practical Applications of Epidemiology

Objectives

Overview of Inter Tribal

Council of Arizona, Inc. (ITCA) Tribal Epidemiology Center (TEC)

• Who we are

• Where we are

• What services are provided

• How to request services and partnerships


ITCA, Inc. Regional Epidemiology Center:

• Established in 1996

• Mission: Empowering the American Indian Tribes in

Arizona, Nevada, and Utah in the further development

of health services and systems

• Purpose: To support Tribally-driven Health Surveillance

Systems that can assess both individual and community

health status, facilitate planning, and manage existing

health services


• Services– Community health profile (CHP) assistance

– Epidemiology and other public health trainings

– Study and survey design

– Data collection and analysis

– Technical report creation and review

– Educational materials for health-related topics

– Coordination of services during outbreaks or disease

cluster investigations

– CHP and Community Health Accreditation (CHA) tool kits

for Tribes coming soon!


• How can I request ITCA, Inc. TEC services?– E-mail ITCA, Inc. TEC for assistance directly at:

[email protected]

– TEC staff will respond within 48 hours and provide you with a fillable

form to complete

– TEC staff will meet with you by phone or e-mail to discuss a project

work plan

– TEC staff will decide with you the format and delivery method of the

final product1

1Please allow at least 2 weeks for project completion, possibly longer depending on the

scope of the project


mailto:[email protected]

Epidemiology Basics

• Epidemiology

– Definition

– How public health professionals use it

• Types of Epidemiology

• Descriptive Epidemiology

– Person, place, time

– Measures

– Relationship between measures

Epidemiology Basics

Epidemiology is defined as:

“…the study of the distribution and determinants

of health-related states or events in specified

populations and the application of this study to

control of health problems.”1

Epidemiology Basics

1 Gordis, L. Modern Epidemiology 2nd Edition. 2000. W.B. Saunders Company, Philadelphia. ISBN 0-7216-8338-X

• It enables public health professionals

to:

– Understand the local disease patterns

– Identify populations at risk for disease

– Establish associations with risk factors and

disease

– Determine causes of disease

– Develop new prevention programs and

policies

– Set health-based standards

Epidemiology Basics

• Descriptive epidemiology1

– Person, place, time

– Measures: counts, proportions, rates

– Explains or quantifies a particular disease or problem

(ex. Cancer rates)

• Analytic epidemiology– Tests a hypothesis

– Measures: relative risk, odds ratios

– Describes associations between a risk factor and a

disease (ex. Smoking and lung cancer relationship)

Epidemiology Basics

1Focus for today’s talk

Epidemiology Basics

• Person– Ex. Diagnosed

Colorectal cancer

cases

• Place– Arizona

Community Health

Analysis Areas

• Time– 1995-2000

– 2001-2004

• Uses statistical measures to describe:

– New cases of disease and death

– People living with disease

– Identify possible risk factors for the disease

Epidemiology Basics

• Counts / Frequency

The number of events (“cases”) that occur

in a population of interest

– Example: There were 87 cancer cases in

Tribe A

• Is this story complete?

• What else would you like to know?

Epidemiology Basics

• Proportions give a magnitude to events

• Useful info might include:

– Time

• 87 cancer cases in 1 year (1999)

– Total Number of Deaths

• 87 cancer deaths/1,000 total deaths = 0.087

• Multiply by 100% 0.087 x 100% =

8.7% of deaths were cancer cases in 1999

Epidemiology Basics

Types of Rates

• Crude rates

• Stratified or Specific Rates

– Better detail

– Uses specific population (age group, sex,

ethnic group, etc.)

– Ex. Cancer death rates in males & females

• Adjusted rates

– age

Epidemiology Basics

• Proportions– Prevalence (NOT a rate)

– Not directly comparable across groups

– Used for public health planning purposes to

determine the burden of disease

• Rates– Incidence and Mortality rates

– Allow health comparisons within and between groups

Epidemiology Basics

Epidemiology Basics

• Incidence rate: Risk of

disease development in

the population (new

cases)

• Prevalence: Fraction of

population with illness in

population

• Mortality rate: Risk of

Death

• Incidence and prevalence

are related:

I X P = Duration

• How do epidemiologists know when rates

are statistically different?

There are measures that can determine if

differences are statistically significant…

– P-values of p<0.05 indicate that measures have a statistically

significant difference

– 95% Confidence intervals that do not overlap are considered a

way to tell if measures show a statistically significant

difference. These intervals can also tell us about the

magnitude of the difference.

Epidemiology Basics

Statistical measures are used to tell a

story…but where do I get data to tell it?

Epidemiology Basics

Practical Applications

of Epidemiology

• Arizona Cancer Registry

• Statistics for working documents

– Scenarios

Practical Applications of

Epidemiology

Arizona Cancer Registry

• Began in 1981

• Mandatory cancer reporting in

1988 Arizona Revised Statute §36-133

• Rules for case reporting in 1992 Arizona Administrative Code Title 9,

Chapter 4

• Provide data to New Mexico

Tumor Registry for American

Indian registry for SEER

statistics

• Population-based NPCR registry:

– Cancer site

– Case demographics

– Year of cancer diagnosis

Arizona Cancer Registry Home page: http://www.azdhs.gov/phs/phstats/acr/

http://www.azleg.state.az.us/ars/36/00133.htm





http://www.azsos.gov/public_services/Title_09/9-04.htm




http://www.azdhs.gov/phs/phstats/acr/



What statistical measures are available?

• Cancer case counts

• Cancer incidence rates1

• Cancer mortality rates2

• Population estimates

– Denominator data

Arizona Cancer Registry

1Age-adjusted incidence rates; 2Crude mortality rates per 100,000

Scenario 1. A Tribal community cancer researcher has heard rumors

from concerned community members that there may be a high risk of

colorectal cancer in her area. From her training, she remembers that

the national trend of age-adjusted incidence rate of colorectal

cancers from 1992-2009 were dropping in the US1. She wants to

determine if her community has a high risk of colorectal cancer

compared to others.

• What are the person, place, and time components?

• What measure is needed to determine risk and can be directly

compared across geographical areas?

• How can I get this information from the Arizona cancer registry?

Statistics for working

documents

1 Age-adjusted colorectal cancer incidence rate trend slides from SEER are included in the presentation.

What data does the researcher need?

• Person

– Colorectal cancer cases among AZ residents and Tribal

community members

• Place

– Arizona state in community health analysis areas (CHAAs)1

• Time

– Not specified

– Data lag, limited to what is available2


documents

1Tribe specific data is not publicly available. Community Health Analysis Areas are used to estimate

Incidence rates based on Census blocks in Tribal areas and may include non-Tribal members.2Cancer data takes at least 18 months to check for completeness from the central registry.http://azdhs.gov/phs/azchaa/CHAA_FAQ.pdf

http://azdhs.gov/phs/azchaa/CHAA_FAQ.pdf

What statistics do we use to determine the

risk of colorectal cancer comparing areas?

Use age-adjusted incidence rates:

• Risk of getting disease

• Comparisons of groups

Use 95% confidence intervals:

• Rate differences are statistically significant

• Magnitude of the difference

• Stability of the rates1


documents

1Rates may be unreliable with small numbers of cases. The 95% CIs will often be a wide range.


documents

Three ways to get the

state data:

• From the home page, go

to the Cancer Data Query

System link

• Contact the Arizona

Cancer Registry Data

Section by e-mail or

phone

• Request services from

TEC


documents






documents

The Cancer Data

Query System,

incidence rates can be

access in two ways:

– Age-adjusted cancer

Incidence rates

– ACR Community

Health Analysis Area

Maps1

1Tribe specific data is not publicly available. Community Health Analysis Areas are used to estimate Incidence rates based on Census blocks in Tribal areas and may include non-Tribal members.


documents

Incidence rates and 95%

Confidence Intervals:

– For AZ

– By Year

– All race/ethnicity

– AI/ANs


documents

AZ colorectal cancer age-adjusted

incidence rates show a decreasing

trend from 1995-2009 for both males

and females1

• The age-adjusted incidence rate of

colorectal cancer in 1995 for AZ

men was 57.8 per 100,000 (95% CI:

54.2-61.4) and in 2009 was 40.9

(95% CI: 38.4-43.4) 2


colorectal cancer in 1995 for AZ

women was 38.1 per 100,000 (95%

CI: 35.2-40.9) and in 2009 was 31.8

(95% CI: 29.6-33.9) 2

1 Results from a trend test would tell us if this downward trend is statistically significant2 Statistically significant difference.


documents

AIs in AZ1:• The age-adjusted incidence rate of

colorectal cancer in 1995 for AI

men was 50.6 per 100,000 (95% CI:

34.9-66.4) and in 2009 was 32.2

(95% CI: 21.8-42.5). In 2005, the

rate was 41.0 (95% CI: 28.8-53.3).


colorectal cancer in 1995 for AI

women was 9.7 per 100,000 (95%

CI: 3.1-16.3) and in 2009 was 18.4

(95% CI: 10.8-25.9). In 2006, the

rate was 30.5 (20.4-40.5).2

1 Results from a trend test would tell us if this downward trend is statistically significant2 Statistically significant difference comparing 1995 and 2006 for women.

The Cancer Data Query

System, incidence rates

can be access in two

ways:


Incidence rates

– ACR Community

Health Analysis Area

Maps1


documents

1Tribe specific data is not publicly available. Community Health Analysis Areas are used to estimate Incidence rates based on Census blocks in Tribal areas and may include non-Tribal members.

• What is an Arizona Community health analysis

area (CHAA)?

CHAA basics:

– NOT Tribal specific data

– Built on the 2000 Census Block groups

– Contain a range of 5,000-190,000 residents

– Cancer cases are assigned based on place of residence

– PO boxes were assigned to the town of the zip code

– About 2% of cancer cases did not get assigned to CHAA

– Additional information on CHAA:

http://www.azdhs.gov/phs/azchaa/CHAA_FAQ.pdf


documents

http://www.azdhs.gov/phs/azchaa/CHAA_FAQ.pdf

• Choose the cancer site and years


documents

• Select colorectal cancers and either

2001-2004 or 1995-2000


documents

• Apply the filter for Indian community „yes/no‟


documents

• 14 CHAA areas had fewer than 10 colorectal cases

• Some CHAA incidence rates appear higher than others

• Navajo Nation CHAA had the highest amount of cases in any CHAA

(n=40) (But not the highest incidence rate!)


documents

CHAA age-adjusted incidence rates

for colorectal cancer from 2001-

20041:

• The 95% CIs indicate that the rates

for Yavapai-Prescott CHAA 282 per

100,000 (95% CI: 0 – 835), Cocopah

CHAA 86.0 (95% CI: 0-254.8) and

other CHAAs with a small number

of cases are unstable2

• The Navajo Nation CHAA has a

stable rate of 13.7 (95% CI: 9.4-

18.0)

• The Fort Mohave [Mojave] CHAA

rate of 39.4 (95% CI: 20.8-57.4) and

Salt River CHAA rate of 77.1 (95%

CI: 40.9-113.3), these CHAAs are

fairly stable2


documents

1 Limited to Indian Community in CHAAs.2 TECs are formalizing a small numbers protocol. Many Agencies do not report rates based on fewer than 20 cases.

What is the researcher‟s story that describes colorectal cancer?

• National and AZ age-adjusted incidence rates for colorectal cancer are decreasing, but

getting screened for colorectal cancer on an individual level is still VERY important

• Among AIs in AZ, age-adjusted incidence rates may have decreased for AI men and may have

increased for AI women from 1995 to 2009, but data is limited

• Navajo Nation CHAA had the highest case count of colorectal cancer (n=40) from 2001-2004

• The age-adjusted incidence rate of 13.7 (95% CI: 9.4-18.0) for colorectal cancers in the

Navajo Nation CHAA is lower than the state and national rates

• The Navajo Nation CHAA age-adjusted incidence rate is lower than Fort Mohave [Mojave]

CHAA 39.4 (95% CI: 20.8-57.4) and Salt River CHAA 77.1 (95% CI: 40.9-113.3) per 100,000.

These differences are statistically significant.

• Other CHAA areas had higher reported rates, but these rates are unstable due to small

numbers of cases


documents

Scenario 2. A multi-disciplinary team of Tribal cancer researchers want to

propose a case control study with several community members in order to

investigating the relationship between esophageal cancer and arsenic in

the drinking water among AI/AN populations in Arizona from 1995-2004.

Writing the project proposal introduction, the researchers want to know:

• What is the person, place, and time understudy?

• What statistics can the team use to describe the problem of esophageal

cancer in AZ?

• How do we get the descriptive cancer data from the registry?

• Does the registry contain the exposure information (e.g., arsenic levels

or other environmental exposures)?

• Does registry information tell us about the association between cancer

and arsenic in the drinking water?


documents


documentsWhat data does the researcher need?

• PersonAI/AN esophageal cancer cases1

• PlaceArizona state

• Time1995-2004Data lag, limited to what is available2

1Tribe specific data is not publicly available. Community Health Analysis Areas are used to estimate

Incidence rates based on Census blocks in Tribal areas and may include non-Tribal members.2Cancer data takes at least 18 months to check for completeness from the central registry.http://azdhs.gov/phs/azchaa/CHAA_FAQ.pdf

http://azdhs.gov/phs/azchaa/CHAA_FAQ.pdf

What statistics do we use to determine the

risk of esophageal cancers among AIs in AZ?

Use age-adjusted incidence rates:

• Risk of getting disease

• Comparisons of groups

Use 95% confidence intervals:

• Rate differences are statistically significant

• Magnitude of the difference

• Stability of the rates1


documents

1Rates may be unreliable with small numbers of cases. The 95% CIs will be a wide range.

The Cancer Data Query

System, incidence rates

can be access in two

ways:


Incidence rates

– ACR CHAA Maps


documents


documents

Age-adjusted incidence rates

of esophageal cancer

per 100,000

• All AZ residents 1995-2009:

– 4.3 per 100,000 (95% CI: 4.0-4.9)

• All AZ men:

– 1995: 6.9 (95% CI: 5.5-8.3)

– 2009: 8.0 (95% CI: 6.8-9.2)

• All AZ women:

– 1995: 1.6 (95% CI: 0-2.2)

– 2009: 1.7 (95% CI: 1.1-2.3)


documents

Age-adjusted incidence rates of

esophageal cancer

per 100,000 among AIs

• All American Indians AZ 1995-2009:

– 3.0 per 100,000 (95% CI: 2.1-3.8)

• American Indian men in AZ:

– 1995: 6.6 (95% CI: 0-15)

– 2009: 5.0 (95% CI: 0-10.8)

• American Indian women in AZ:

– 1995: 3.5 (95% CI: 0-9.1)

– 2009: 3.1 (95% CI: 0-7.3)

What is the researchers story for the proposal?

• In AZ, the age-adjusted incidence rate of esophageal cancer is 4.3

per 100,000 (95% CI: 4.0-4.9) from 1995-2009

• Among AIs in AZ, the age-adjusted incidence rate of esophageal

cancer of 3.0 per 100,000 (95% CI: 2.1-3.8) from 1995-2009, which

is lower than the state rate; and, the difference is statistically

significant.

• The registry does not include environmental exposure information

like arsenic

• The registry information does not tell us about associations with

exposure and disease risk


documents

• Overview of Inter Tribal Council of

Arizona (ITCA), Inc. Tribal Epidemiology

Center (TEC)

• Epidemiology Basics

• Practical Applications of Epidemiology

– Data Scenarios 1 & 2

Summary

2214 North Central Avenue, Phoenix, Arizona 85004

p 602.258.4822, f 602.258.4825

www.itcaonline.com

Additional

information

P-values

• Estimated probability of rejecting the null

hypothesis (H0) of a study question.

• Null hypothesis is usually a hypothesis of "no

difference"– Ex: there is no difference between high perceived risk and low

perceived risk groups

• Alternative hypothesis is a hypothesis of

“difference”– Ex: there is a difference between high perceived risk and low

perceived risk groups

More Statistical Tests

P-values

• To be statistically significant, the p-value

will usually be set to less than 0.05 (p <

0.05)

• If the p-value is less than 0.05, then the

null hypothesis can be rejected and the

alternative hypothesis can be accepted

Statistical Tests

95% Confidence Intervals (95% CIs)

• A CI consists of a range of values that act as

good estimates of the unknown population

parameter

– Ex: A 95% CI is the interval that you are 95% certain

contains the true population value as it might be

estimated from a much larger study.

• It is used to indicate if a measure is statistically

significance of an estimate

Statistical Tests

95% Confidence Intervals (95% CIs)

• Can tell us about the magnitude of measure

– Wide vs. narrow intervals

– Wide intervals can indicate small sample or low

power

– Whether the measure is reliable

Statistical Tests

Public cancer data resources

• National Program of Cancer Registries (NPCR) http://www.cdc.gov/cancer/npcr/

• Surveillance Epidemiology and End Results (SEER) http://seer.cancer.gov/

• National Cancer Data Base (NCDB) http://www.facs.org/cancer/ncdb/

• Behavioral Risk Factor Surveillance Survey (BRFSS) http://www.cdc.gov/brfss/

• Agency for Healthcare Research and Quality – Libraryhttp://www.ahrq.gov/clinic/ehclibrary/reslibcancer.htm

• PubMedhttp://www.ncbi.nlm.nih.gov/pubmed/

Public Cancer Data

Resources

http://www.cdc.gov/cancer/npcr/

http://www.cdc.gov/cancer/npcr/

http://seer.cancer.gov/

http://seer.cancer.gov/

http://www.facs.org/cancer/ncdb/



http://www.cdc.gov/brfss/



http://www.ahrq.gov/clinic/ehclibrary/reslibcancer.htm



http://www.ncbi.nlm.nih.gov/pubmed/



annual arizona conference for tribal bccedp collaboration, flagstaff, az

Health & Medicine