Background/Purpose: Patients with systemic sclerosis (SSc) can die prematurely of disease-associated complications. Over the past 2 decades, several advances in the treatment of SSc-associated complications may have affected SSc outcomes. For example, the two-year survival of patients with SSc-associated pulmonary arterial hypertension has improved from 47% to 71% with the availability of prostanoids. The influence of these advances on long-term SSc mortality in the general population remains unknown. Here, we tested the hypothesis that death from SSc is decreasing at younger ages over time.

Methods: This is a population-based study using a national mortality database of all U.S. residents, 1968 through 2015. First, we calculated the proportions of deaths for SSc and for all other causes (non-SSc) by age groups for each year from 1968 through 2015 and performed joinpoint trend analysis to estimate annual percent change (APC) and average APC (AAPC) in the proportion of deaths by age. Second, we calculated age-standardized mortality rate (ASMR) for SSc and non-SSc causes and ratio of SSc-ASMR to non-SSc-ASMR by age groups for each year from 1968 through 2015 and performed joinpoint trend analysis to estimate APC and AAPC for these measures by age groups.

Results: From 1968 through 2015, SSc was recorded as the underlying cause of death in 46,798 deaths. In 1968, 23.4% of all SSc deaths as compared to 13.5% of non-SSc deaths occurred at a younger (≤44 years) age group (p< 0.001, Chi-square test). In this age group, the proportion of annual deaths decreased more for SSc than for non-SSc causes: from 23.4% in 1968 to 5.7% in 2015 at an AAPC of -2.2% (95% CI, -2.4% to -2.0%) for SSc, and from 13.5% to 6.9% at an AAPC of -1.5% (95% CI, -1.9% to -1.1%) for non-SSc. Thus, in 2015, the proportion of SSc and non-SSc deaths in ≤44 year age group was no longer significantly different. The percent of deaths in the 45-54 year age group also decreased more for SSc than for non-SSc over the 48-year period, but no statistical change was noted in the 55-64 year age group. However, in ≥65 year age group, the proportion of SSc deaths increased more for SSc than for non-SSc causes, indicating that SSc patients were dying later in life. Consistent with this observation, ASMR for SSc decreased from 1.0 (95% CI, 0.8-1.2) in 1968 to 0.4 (95% CI, 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%) in ≤44 year age group. The ratio of SSc-ASMR to non-SSc-ASMR also decreased in this age group (cumulative, -20%; AAPC -0.3%).

Conclusion: Mortality for SSc has steadily decreased in younger ages.  Young individuals with SSc now make up the same proportion of deaths as those without SSc.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/systemic-sclerosis-deaths-at-younger-ages-have-decreased-over-the-past-five-decades/