Background/Purpose:  PM and DM are rare chronic inflammatory disorders of muscle, and data on long-term prognosis and outcomes are lacking.  Previous studies have reported 5-year survival rates of 60-75% and standardized mortality ratios (SMRs) ranging from 1.75 to 2.92.   Through a better understanding of mortality and its causes, those at increased risk of premature death can be identified and treated accordingly, thereby improving management of these conditions, and therefore also outcomes. The aim of this study was to determine whether the mortality of a cohort of patients with polymyositis (PM) and dermatomyositis (DM) is significantly different from that of the general UK population, and whether the presence or absence of myositis-specific and myositis-associated autoantibodies influences mortality.

Methods:  Patients entered onto the myositis database at our tertiary referral centre were included.  Information on patient deaths was collected retrospectively.  The National Health Service (NHS) Strategic Tracing Service was used to establish which patients had died and which were still alive.  Date and cause of death was confirmed by death certificate from the Registry of Births, Marriages and Deaths.  Standardized mortality ratios (SMR) were calculated by matching the patient data to single-year, 5-year age-banded England and Wales data from the Office of National Statistics. 

Results:  Out of 86 patients with PM and DM (57 PM, 65 female), there were 21 deaths – 15 female and 6 male.  The SMR for the total cohort was 2.20 (95% CI 1.36-3.36), for PM was 2.12 (95% CI 1.16-3.56) and for DM was 2.38 (95% CI 0.96-4.90).  SMRs were higher in females compared with males overall and in the PM subgroup, however the SMR was higher in males with DM compared with females. There was a trend towards higher death rates in those without myositis-specific or myositis-associated autoantibodies (OR 2.11, 95% CI 0.68-7.43).  The leading causes of death were infection (33%), malignancy (28.6%) and cardiovascular disease (23.8%).

Conclusion: Patients with PM and DM are at 120% increased risk of mortality; and infections, cardiovascular disease and malignancy account for the majority of deaths.  Females, in particular those with PM, and autoantibody-negative patients are at higher risk of death.  Early identification and aggressive management of infections, thorough cardiovascular evaluation, and targeted malignancy screening may improve outcomes in these conditions.

---

« Back to 2013 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-in-polymyositis-and-dermatomyositis-a-single-centre-study/