Mortality trends in polymyositis and dermatomyositis: A general population-based study

Area of Science:

• Rheumatology
• Epidemiology
• Public Health

Background:

• Polymyositis (PM) and dermatomyositis (DM) are rare autoimmune diseases.
• Understanding mortality trends in PM and DM is crucial for patient care and resource allocation.

Purpose of the Study:

• To evaluate mortality trends in polymyositis (PM) and dermatomyositis (DM) patients.
• To compare mortality rates between early (1997-2005) and late (2006-2014) diagnosis cohorts.

Main Methods:

• Utilized a British Columbia administrative health database.
• Identified incident PM/DM cases and matched them with non-PM/DM controls.
• Compared mortality rates, hazard ratios (HRs), and rate differences between early and late cohorts.

Main Results:

• Mortality rates per 1000 person-years were higher in early PM/DM cohorts compared to late cohorts.
• Multivariable HRs for PM were 2.4 (early) and 2.0 (late), with significant rate differences observed.
• Similar trends of higher mortality and risk were noted for dermatomyositis patients.

Conclusions:

• Excess mortality in polymyositis and dermatomyositis patients has decreased in recent years.
• A considerable premature mortality gap remains, even in the later diagnosis cohort.
• Further research is needed to address the persistent mortality disparities in PM/DM.