Trends In Mortality Rates and Age of Death In Sickle Cell Disease (SCD): 1979–2005

Abstract 736

While improvements in care have resulted in significant decreases in mortality for children with SCD, it is unclear if similar decreases in mortality rates have occurred in adults with the disease. The purpose of this research is to describe mortality rates and trends in age of death for those with SCD over the last 3 decades. We used the National Center for Health Statistics Multiple Cause of Death (MCOD) files to examine age at death and calculate mortality rates from 1979–2005. ICD9 and ICD10 codes for SCD were used as appropriate to identify sickle cell related deaths. Mortality rates were calculated as deaths per 100,000 African American population. The number of African Americans each year was determined using available census data. Trends in mortality rates were examined using negative binomial regression and age of death was examined using t-tests and linear regression. After excluding certificates with codes for sickle trait and those with multiple sickle codes we identified 16,654 sickle-related deaths. The age range was 0 to 107 years. Mean age of death was significantly different for men (33.4, 95% CI [33.0, 33.7]) and women (36.9, 95% CI [36.5, 37.4]). SCD was the most common listed underlying cause of death (COD) at 62.8%. Infection was the second most common COD (5.9%). Controlling for sex and the presence of infection as COD, the mean age of death increased significantly by 0.08 years (p<0.001) each year over the time period studied, with men on average dying 4.3 years earlier than women (p<0.001). The mean age of death in 2005 was 43 yrs for women and 37 yrs for men. Those with COD of pulmonary hypertension, stroke and renal disease had a significantly older age of death than those without those diagnoses, while having infection as the underlying COD was associated with a younger age at death. The overall mortality rate increased by 0.7% (p<0.001) each year over the time period studied. Mortality rates for adults and children over time are shown in Figure 1. The adult (>19 yrs) mortality rate increased by 1% (p<0.001) each year over the time period studied. The pediatric mortality rate decreased by 3% (p<0.001) each year over the time period studied. When controlling for the pediatric mortality rate the adult mortality rate increased by 1.6% (p<0.001) each year. This data confirms prior studies showing a significant decrease in mortality for children with sickle cell disease over the last 30 yrs. The mortality rate for the adult population appears to be steadily increasing over the same time period. It seems unlikely that this is due merely to an influx of younger patients surviving to adulthood. Further investigation as to the cause of the increasing mortality rate in adults is needed.

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