Statin-associated immune-mediated necrotizing myopathy in Hispanic Americans

Area of Science:

• Rheumatology
• Immunology
• Epidemiology

Background:

• Idiopathic inflammatory myopathies (IIM) present with muscle weakness and inflammation.
• Immune-mediated necrotizing myopathy (IMNM) is a subtype of IIM linked to anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (anti-HMGCR) antibodies.
• Regional disparities in anti-HMGCR antibody IMNM prevalence have been observed.

Purpose of the Study:

• To compare the epidemiology of IIM and IMNM in adult Hispanic and non-Hispanic Caucasian populations in the Southwestern USA.
• To investigate differences in risk factors, clinical characteristics, and outcomes between these groups.

Main Methods:

• Retrospective analysis of 97 adult patients with IIM, self-identified as Hispanic or non-Hispanic.
• Statistical comparisons of diabetes mellitus, hyperlipidemia, statin exposure, myopathy diagnosis, muscle histology, autoantibodies, echocardiography, interstitial lung disease, therapy, and outcomes.

Main Results:

• Hispanics constituted 64% of the study cohort.
• Increased prevalence of statin-induced anti-HMGCR antibody IMNM (22.6% vs 5.7%) and diabetes mellitus (46.8% vs 25.7%) in Hispanics.
• Lower prevalence of cancer-associated IIM in Hispanics (11.3% vs 31.4%) compared to non-Hispanics.

Conclusions:

• Hispanic populations in the Southwestern USA have a higher incidence of statin-induced anti-HMGCR antibody IMNM.
• A lower prevalence of cancer-associated IIM was noted in Hispanic individuals.
• Further research is needed to determine if genetic, environmental, or increased statin exposure due to diabetes contributes to these observed differences.