UCLA

Objective

We aimed to assess systemic sclerosis (SSc) mortality by age in the general population over the past five decades.

Methods

This is a population-based study using a national mortality database and census data of all United States residents. We calculated the proportions of deaths for SSc and for all other causes (non-SSc) by age, and calculated age-standardized mortality rate (ASMR) for SSc and non-SSc, and the ratio of SSc-ASMR to non-SSc-ASMR by age groups for each year from 1968 through 2015. We performed joinpoint regression to estimate average annual percent change (AAPC) for each of these parameters.

Results

SSc was recorded as the underlying cause of death in 5,457 decedents aged ≤44 years, 18 395 aged 45-64, and 22 946 aged ≥65 from 1968 through 2015. At ages ≤44, the proportion of annual deaths decreased more for SSc than for non-SSc: AAPC, -2.2% (95% CI, -2.4% to -2.0%) for SSc vs -1.5% (-1.9% to -1.1%) for non-SSc. Consistently, SSc-ASMR decreased from 1.0 (95% CI, 0.8-1.2) in 1968-0.4 (0.3-0.5) per million persons in 2015, a cumulative decrease of 60% at an AAPC of -1.9% (95% CI, -2.5% to -1.2%) at ages ≤44. The ratio of SSc-ASMR to non-SSc-ASMR ratio also decreased (cumulative -20%; AAPC -0.3%) in ≤ 44-year group. In contrast, those aged ≥65 experienced a steep increases in SSc-ASMRs (cumulative 187.0%; AAPC 2.0% [95% CI, 1.8-2.2]) and SSc-ASMR: non-SSc-ASMR ratio (cumulative 395.4%; AAPC 3.3% [95% CI, 2.9-3.7]).

Conclusion

Mortality for SSc has steadily decreased at younger ages over the past five-decades.