Retrospective analysis of myositis-specific antibody-positive veteran survival between 2011 and 2023

The rarity of myositis-specific antibodies (MSAs) presents challenges in the assessment of idiopathic inflammatory myopathy (IIM) subsets. We leveraged a national database to identify MSA-positive veterans and compare all-cause mortality across antibody subsets in a singular population.

A retrospective analysis of veteran adults with MSA testing between 1/1/2011 and 12/31/2021 was performed. A minimum of two outpatient International Classification of Disease 9 or 10 visit codes from specialty clinics at least 30 days apart with one creatine phosphokinase level above the upper limit of normal was used to assign a presumptive IIM diagnosis. Current Procedural Terminology codes were used to identify lung computerized tomography imaging studies. Kaplan-Meier survival and Cox proportional regression analyses were performed for the primary outcome of mortality from any cause with a censor date of 12/10/2023.

A total of 1749 veterans met inclusion criteria. Jo-1 was the most common MSA (75.0%), followed by PL-7 (8.9%) and HMGCR (3.5%). Our cohort was male-predominant (83.4%) with a robust representation of non-White veterans (47.3%). Jo-1 individuals had longer survival compared to non-Jo-1 (75% survival at 6.5 years, 95% CI 5.8-7.1 vs 3.4 years, 95% CI 2.7-5.2, log rank p < 0.001). Univariate and multivariable Cox proportional hazard analyses showed that non-Jo-1 status was associated with higher mortality, irrespective of antibody titer. There were no sex differences in mortality or lung disease prevalence.

Age, lung involvement, and non-Jo-1 MSA status are associated with increased veteran mortality in this large, male-predominant cohort. Key Points • Jo-1 antibody positivity was associated with the best survival among MSA subsets. • The incidence of lung involvement was equal among Jo-1-positive men and women. • Veteran survival was chiefly determined by MSA subtype, irrespective of antibody titer.