Trends in Dermato-polymyositis Mortality, 1999-2022: A Nationwide Population-based Study, United States.

Objective: We evaluated trends in dermato-polymyositis (DPM) mortality relative to all-cause mortality in the United States, 1999-2022.

Methods: We used the Center for Disease Control and Prevention's databases (Multiple Causes of Death for 1999-2020 and Provisional Mortality Statistics for 2021 and 2022) to obtain death counts for DPM and non-DPM (all causes other than DPM). We calculated age-standardized mortality rates (ASMR) for both groups and computed the ratio of DPM-ASMR to non-DPM-ASMR for each of the 24 years. We performed joinpoint regression analysis to estimate annual percent change (APC) in DPM and non-DPM ASMRs and in the DPM-ASMR:non-DPM-ASMR ratios, overall and by sex, age, and race/ethnicity.

Results: There were 12,882 DPM and 63,549,485 non-DPM deaths during 1999-2022. Mortality decreased at a higher APC (-3.8% [95% CI, -4.3%, -3.4%]) for DPM than non-DPM (-1.2% [95% CI, -1.5%, -0.9%]) until the start of the COVID-19 pandemic, when it increased for both at similar APCs. Consequently, the ratios of DPM-ASMRs to non-DPM-ASMRs decreased over these 24 years in all subgroups. The DPM-ASMR to non-DPM-ASMR ratios were higher in females than males, and in younger individuals (≤64 years) than those ≥65 years. The odds of premature death were higher for DPM than non-DPM. Non-Hispanic Black, Hispanic, and non-Hispanic others had higher DPM-ASMR to non-DPM-ASMR ratios than White individuals.

Conclusion: DPM mortality decreased at a higher rate than all-cause mortality until the pandemic, when it proportionately increased for both DPM and all causes. Females, younger, Black, Hispanic, and non-Hispanic other individuals had higher DPM mortality relative to all-cause mortality. Findings highlight the need for improved screening, earlier intervention, and targeted efforts to address racial/ethnic disparities in DPM outcomes.