The Misinterpretation of Health Inequalities in the United Kingdom James P. Scanlan Washington, DC, USA jps@jpscanlan.com

Principal Points - Background During the almost 30 years in which socioeconomic inequalities in health have been studied in the UK, the perception has been that, at least as to mortality, those inequalities have been increasing. Generally these inequalities have been measured in terms of relative differences, i.e., the ratio of the mortality rate of the disadvantaged group to the mortality rate of the advantaged group. Similar perceptions exist with respect to racial, socioeconomic, and geographic health inequalities throughout the industrialized world, with the matter frequently being characterized in terms that “despite declining mortality, inequalities in mortality have increased.”

Principal Points – Thesis (1) Almost all health inequalities research is suspect for failure to recognize the way relationships between the rates at which two group experience (or avoid) an outcome are influenced by the prevalence of the outcome. Most notably, researchers have failed to recognize the tendency whereby, when an outcome like mortality declines, relative differences in experiencing it increase, while relative differences in avoiding it decline.

Principal Points – Thesis (2) Thus, relative differences in mortality have tended to increase, because of declining mortality, not despite declining mortality, and to be accompanied by declining relative differences in survival rates. But all measure of differences in experiencing or avoiding an outcome tend to be affected by changes in the prevalence of an outcome, raising questions of whether we can determine whether inequalities are increasing or decreasing in any meaningful sense.

Interpretive Rule 1(IR1) When two groups differ in their susceptibility to an outcome, the rarer the outcome (a) the greater tends of be the relative difference in rates of experiencing it, and (b) the smaller tends to be the relative difference in rates of avoiding it.

References (1) “Can We Actually Measure Health Disparities?” Chance, Spring 2006. “Race and Mortality,” Society, Jan-Feb 2000* “Divining Difference,” Chance, Spring, 1994. “The Perils of Provocative Statistics,” The Public Interest, Winter 1991 2001 Oslo Presentation* 2006 Athens Presentation* * Available online at jpscanlan.com

References (2) Carr-Hill R., Chalmers-Dixon P. 2005 The Public Health Observatory Handbook of Health Inequalities Measurement. Oxford: South East Public Health Observatory. (http://www.sepho.org.uk/extras/rch_handbook.aspx). Keppel K., Pamuk E., Lynch J., et al. 2005. Methodological issues in measuring health disparities. Vital Health Stat 2 (141). (http://www.cdc.gov/nchs/data/series/sr_02/sr02_141.pdf)

Fig.1 – Proportion Disadvantaged Group (DG) Comprises of Total Below Each Cutoff Point

Fig. 2 – Ratio of Fail Rate of Disadvantaged Group (DG) to Fail Rate of Advantaged Group (AG)

Fig. 3 – Ratio of Pass Rate of Advantaged Group (AG) to Pass Rate of Disadvantaged Group (DG)

Supp. Fig. 4 – Ratio of Fail Odds of Disadvantaged (DG) Group to Fail Odds of Advantaged Group (AG)

Fig. 5 - Absolute Difference Between Fail (or Pass) Rates of Disadvantaged and Advantaged Groups

Implications (1) We don’t really know whether inequalities have been increasing or decreasing in any meaningful sense. It is not clear that there exists tools for measuring changes over time. A Word on Morbidity

Implications (2) Policy Implications Whitehall Studies and inferences thereon Large mortality differentials in Sweden and Norway, large racial differences among the highly educated

Implications (3) Ameliorative interventions; exacerbating factors Legal settings (mortgage rejection rate disparities, termination rate disparities) What is a large difference?

Supp. Fig. 1 – Fail Ratios, Pass Ratios, Odds Ratios