Two Approaches for Comparing Characteristics of Decedents With Sickle Cell Disease: Inconsistencies and Implications

During the past several decades, survival rates for sickle cell disease (SCD) have substantially increased, with many people now living well into middle adulthood. To understand trends in mortality and survival patterns, research has taken 2 diverging approaches to ascertaining the death status for people with SCD. Single-source approaches rely on death certificates alone to identify people with SCD who died, while multiple-source approaches first identify those with SCD and then link them to death certificates to ascertain mortality status. This study evaluated these 2 approaches in understanding SCD mortality.

We used 16 years of data (2004 through 2019) from the Sickle Cell Data Collection programs in California and Georgia. Drawing on these population-based surveillance systems and using the single- and multiple-source approaches, we constructed SCD decedent cohorts. For each approach, we examined the number of decedents with SCD, differences in demographic characteristics, and differential causes of death.

The single-source approach identified 1788 deaths among people with SCD, while the multiple-source approach identified 2524 such deaths, an increase of 41%. While many of the demographic characteristics were similar between the approaches, the multiple-source approach identified the average age of death to be 3.5 years greater than that of the single-source approach. While the multiple-source approach identified more decedents with SCD, the death records contained a higher percentage of nonspecific cause-of-death codes relative to the single-source approach.

Researchers should be aware of the differences between the single- and multiple-source approaches when analyzing and interpreting mortality patterns among people with SCD. Prior estimates based on single-source approaches may be biased.