Mortality Trends in Polymyositis and Dermatomyositis in Mexico: A General Population-Based Study From 2000 to 2019

Introduction: Patients with polymyositis and dermatomyositis (PM/DM) are prone to multiple complications that may lead to increased mortality rates. Data about PM/DM mortality in Mexico are lacking.

Objective: The aim of this study was to assess mortality trends in PM/DM in Mexico across 2 decades (2000-2019), overall, by sex, age group, and geographic region.

Methods: From 2000 to 2019, PM/DM deaths were identified in Mexican open-access health databases using the International Classification of Diseases, 10th Revision. Age-standardized mortality rates (ASMRs) per 100,000 inhabitants were calculated for PM/DM and non-PM/DM deaths by sex and geographic region. The annual percent change (APC) in ASMR was calculated using Joinpoint Regression Software.

Results: We found 11.3 million non-PM/DM deaths and 1456 PM/DM deaths in Mexico during the period 2000-2019. Seventy percent of PM/DM deaths occurred in females. PM/DM ASMR was 0.06-0.07/100,000 inhabitants and higher in females (0.08-0.11/100,000). Remarkably, 40% of PM/DM deaths happened in individuals younger than 45 years. This was almost double the percentage than in non-PM/DM deaths. A significant PM/DM ASMR downtrend was identified from 2007 to 2017 (APC, -3.2%; 95% confidence interval, -5.3 to -1.0; p = 0.008), whereas mortality trends were stable for non-PM/DM deaths. No significant changes through time were identified in PM/DM mortality by geographic region in Mexico; however, an increment in PM/DM to non-PM/DM ASMR ratio was detected in the north (+17.6%) and southeast (+84.9%) of Mexico.

Conclusions: Mexico's PM/DM mortality rates have significantly decreased over the past 2 decades, particularly from 2007 to 2017. This trend is more pronounced among younger individuals and those outside the country's southeastern region.