James P. Scanlan, Attorney at Law

Mortality/Survival Illustration

(May 27, 2013)

 Prefatory note:  This subpage of the Scanlan’s Rule is closely related to the following other subpages that use particular types of data to illustrate the pattern whereby the rarer an outcome the greater tends to be the relative difference in experiencing it and the smaller tends to be the relative difference in avoiding it: Framingham Illustrations, NHANES Illustrations,  Life Tables Illustrations, Income Illustrations, Credit Score Illustrations.

The Mortality and Survival page discusses the fact that, particularly in studies concerning racial differences in cancer outcomes, researchers commonly refer to relative differences in survival and relative differences in mortality interchangeably, often stating they are analyzing one relative difference while in fact analyzing the other, but without recognizing that the two relative differences tend to change in opposite directions as overall survival rates change or that more survivable conditions tend to show larger relative differences in mortality but smaller relative differences in survival than less survivable conditions.  Several of the tables on that page illustrate the pattern whereby the rarer an outcome the greater tends to be the relative difference in experiencing it and the smaller tends to be the relative difference in avoiding it.  These include Table N1, which presents an example where localized cancer shows a smaller relative difference in survival but larger relative difference in mortality than regionalized cancer.  Table 1 below present similar data on five-years survival/mortality for nine types of cancer according to three stages (local, regional, distant) based on Figure 4 of the American Cancer Society’s Cancer Facts and Figures for African Americans 2013-2014.  The final column also shows the EES, for estimated effect size, which is a measure of disparity theoretically unaffected by the prevalence of an outcome (as discussed on the Solutions subpage of Measuring Health Disparities page). 

Table 1.  White and black five-year survival rates by type of cancer and stage with ratio of white survival rate to black survival rate and black mortality rate to white mortality rate and estimate effect size (from American Cancer Society data) [refb4127a2]

There are only minor departures from the pattern whereby as survival decreases from stage to stage, relative differences in mortality decrease while relative differences in survival increase.

One observes a more striking pattern when the focus is limited to the stages with the highest and lowest survival and the common situation where the white survival rate is greater than the black survival rates for both stages, as shown in Table 2. 

Table 2.  White and black five-year survival rates by type of cancer and stage with ratio of white survival rate to black survival rate and black mortality rate to white mortality rate and estimated effect size (limited to local and distant and situations where white survival is greater than black survival for both stages) (from American Cancer Society data) [refb4127a4]