The term 'disparity' generally refers to inequality or some kind of difference between groups. Health researchers differ in the ways they define a health disparity. Here are some definitions of disparities related to cancer:

1. Center to Reduce Cancer Health Disparities, National Cancer Institute

   “A difference in the incidence, prevalence, mortality, and burden of cancer and related adverse health conditions that exist among specific population groups in the United States.” NCI Center to Reduce Cancer Health Disparities (CRCHD)

2. Minority Health and Health Disparities Research and Education Act of 2000

   “A population is a health disparity population if...there is a significant disparity in the overall rate of disease incidence, prevalence, morbidity, mortality, or survival rates in the population as compared to the health status of the general population.” [Minority Health and Health Disparities Research and Education Act of 2000 (47, page 2498)]

3. NIH Strategic Research Plan

   “Health disparities are differences in the incidence, prevalence, mortality, and burden of diseases and other adverse health conditions that exist among specific population groups in the United States.” [NIH Strategic Research Plan and Budget to Reduce and Ultimately Eliminate Health Disparities, Vol. 1, Fiscal Years 2002–2006]

4. Dr. David Satcher Former U.S. Surgeon General

   “For all the medical breakthroughs we have seen in the past century, there remain significant disparities in the medical conditions of racial groups in this country...[W]hat we have done through [Healthy People 2010] is to make a commitment—really, for the first time in the history of our government—to eliminate, not just reduce, some of the health disparities between majority and minority populations.” [Dr. David Satcher Former U.S. Surgeon General, 1999 (48, page 18–19)]

 What differences do you observe in these definitions of cancer disparities?

 What are the measurement issues inherent in the various definitions of health disparities we have reviewed? If you were going to define how to measure health disparity what kind of issues might come to your mind?

Elimination of Health Disparities

Eliminating health disparities has been adopted as a goal at several US health-related agencies.

“The second goal of Healthy People 2010, to eliminate health disparities, includes differences that occur by gender, race or ethnicity, education or income, disability, geographic location, or sexual orientation.” https://www.cdc.gov/nchhstp/healthdisparities/

If the goal is to eliminate a disparity, we must ask how a disparity is identified and measured. Otherwise, how will we know if we have succeeded?

Some important documents from the US government for researches involved with health disparities that attempt to answer how to identify and measure disparity are listed below:

The NCI lists 13 issues to be considered when attempting to measure health disparities.

Issues in Evaluating Measures of Cancer Health Disparities

1. Is it relative or absolute disparities that you are interested in?
2. Are you talking about total disparity or differences in social groups?
3. Reference groups - who will you be referring to?
4. Do the social groups have a “natural” order?
5. How many social groups will you use?
6. Should you vary the groups based on population size?
7. What part does the socioeconomic dimension play?
8. Do you monitor populations over time?
9. How do you handle transfers?
10. Subgroup consistency
11. Decomposability
12. Scale independence
13. Transparency / Interpretability for policymakers

Geography is not specifically mentioned in this list. Yet the definition for the elimination of health disparities includes geographic location. What units of geography should be associated with a disparity? How do we measure geographic disparity?

The NCI monograph provides examples of some types of disparity. (this document is posted in Week 8 materials)