Steady decrease in systemic sclerosis mortality rates at younger ages over the past five decades

Abstract

Abstract Objective We aimed to assess 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 the census data for all US residents. We calculated the proportions of deaths for SSc and for all other causes (non-SSc) by age, and calculated age-standardized mortality rates (ASMRs) 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 the average annual percent change (AAPC) for each of these parameters. Results SSc was recorded as the underlying cause of death in 5457 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 to 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 SSc-ASMR:non-SSc-ASMR ratio also decreased [cumulative –20%; AAPC –0.3% (95% CI, –1.15% to 0.55%)] in the ≤44-years group. In contrast, those aged ≥65 experienced a steep increase in the SSc-ASMR [cumulative 187.0%; AAPC 2.0% (95% CI, 1.8–2.2)] and the 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.