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A cohort study of Medicare and Medicaid beneficiaries with sickle cell disease (SCD) showed a life expectancy of just 52.6 years, well below that of the general population.

And among SCD patients, survival varied by sex and insurance status. Men, individuals covered by Medicare for disabilities or end-stage renal disease (ESRD), and the dual-eligible were groups with particularly short life expectancies, according to Anirban Basu, PhD, a health economist and statistician at the University of Washington in Seattle, and colleagues.

These estimates, based on data spanning 2008 to 2016, "highlight the persistent life expectancy gap for SCD patients and the enduring premature mortality throughout adulthood," Basu and colleagues reported in .

It remains unknown what clinical and socioeconomic factors might explain the SCD survival disparity across insurance types.

SCD, while rare, disproportionately affects , according to government statistics. Ultrasound screenings and recommended treatment with hydroxyurea have been known to be lacking in children with sickle cell anemia and Medicaid insurance.

The current study "highlights that there is a persistent life expectancy gap among the individuals with sickle cell disease, even though they are covered by public insurance," said health economist and study coauthor Boshen Jiao, PhD, MPH, in a press release. "The clinical community has known that SCD can be an extremely burdensome condition, however, this study puts numbers behind that burden using real patient data."

CDC's latest are 76.4 years for the U.S. population as whole, split between men (73.5 years) and women (79.3 years).

Several years ago, a projection had given SCD patients a life expectancy of 54 years vs 76 years for a non-SCD population matched on age, sex, and race or ethnicity. The gap in quality-adjusted life expectancy was 33 years versus 67 years, according to .

For the present study, Basu's group included 94,616 individuals with diagnosed SCD who received real-world patterns of common care (with the exception of transplant), based on Medicare and Medicaid claims data from 2008 to 2016.

Of the individuals in the study 5% had Medicare Old Age & Survivors Insurance, 4% had Medicare disability insurance benefits or ESRD benefits, 48% had Medicaid, and 43% were dually eligible for Medicare and Medicaid.

Study authors used Kaplan-Meier analyses to estimate period life tables and lifetime survival curves for individuals with SCD, and computed expected life expectancies at ages 18, 35, 45, 65, and 85. These estimates came out to:

• 52.6 years at birth
• 35.4 more years at age 18
• 24.1 more years at age 35
• 19.6 more years at age 45
• 13.2 more years at age 65
• 5.4 more years at age 85

Basu and colleagues found that survival rates were high during childhood and declined to a survival probability of 0.980 (95% CI 0.977-0.984) at the age of 18. Survival probabilities then declined rapidly in adulthood: to 0.804 (95% CI 0.795-0.815) at 30 years, 0.628 (95% CI 0.616-0.641) at 45 years, 0.267 (95% CI 0.255-0.279) at age 65, and 0.070 (95% CI 0.064-0.075) at age 85.

This decline confirms the "general recognition that survivorship into adulthood for children with SCD is now a less problematic issue, but early mortality among adults remains concerning," the authors observed.

Among the caveats of the study was the exclusion of SCD populations with commercial insurance or no insurance, limiting the generalizability of the results. What's more, the investigators acknowledged the lack of stratification by genotype due to limited sample size and potential errors in the claims database.

"Also, our analysis did not capture the possible health outcome change due to the uptake of recently approved emerging therapies which have been phased in over recent years. We recommend future research to investigate the latest survival trends in the SCD population, reflecting the quickly-evolving landscape of SCD treatments," they wrote.

Hydroxyurea was, until 2017, the only drug on the market to reduce the painful and frequent vaso-occlusive crises associated with SCD. Since then, L-glutamine (Endari), , and have been FDA approved for SCD.

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