Statin-associated immune-mediated necrotizing myositis in Native Americans.

OBJECTIVES: Statin-associated immune-mediated necrotizing myopathy (IMNM) and idiopathic inflammatory myositis (IIM) are myopathies with overlapping features. This study compared the manifestations of IMNM to IIM in Native Americans. METHOD: Twenty-one Native American patients with inflammatory myopathy (IM) were characterized as to diabetes mellitus, hyperlipidaemia, statin exposure, myopathy diagnosis, muscle histology, autoimmune and myositis-specific autoantibodies, therapy and outcome. RESULTS: IM consisted of 52.4% IMNM, 42.9% IIM and 4.8% metabolic myopathy. IMNM vs IIM patients were older [61.6 years (s.d. 9.8) vs 39.8 (14.3)], diabetes mellitus (100% vs 55.6%), hyperlipidaemia (100% vs 33.3%), statin-exposure (100% vs 22.2%), creatine kinase [CK; 11 780 IU (s.d. 7064) vs 1707 (1658)], anti-3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) antibodies (85.7% vs 11.1%) and necrotizing IM (81.8% vs 11.1%), but shorter disease duration [26.2 months (s.d. 395) vs 78.4 (47.9)], RP (9.1% vs 55.6%), cutaneous manifestations (0% vs 55.6%), ANA (18.2% vs 66.7%) or any autoantibody (18.2% vs 88.9%) (all P < 0.05). MRI abnormalities, histologic IM, myositis-specific autoantibodies, pulmonary hypertension, oesophageal dysfunction, interstitial lung disease, disability and persistently elevated CK were similar. IMNM vs IIM was treated more with IVIG (72.7% vs 11.1%; P = 0.009) and less with antimetabolites (45.5% vs 88.9%; P = 0.05) and rituximab (18.2% vs 55.6%; P = 0.09). CONCLUSIONS: IMNM may occur in Native Americans and is associated with diabetes mellitus, hyperlipidaemia, statin use and older age and is characterized by marked CK elevation, necrotizing myopathy and anti-HMGCR antibodies with few cutaneous or vascular manifestations.

Systemic sclerosis in Native Americans of the American Southwest.

OBJECTIVE: Many indigenous non-Caucasian populations, including Native Americans, have been reported to have higher rates, distinct clinical phenotypes, increased complications, and greater severity of systemic sclerosis (SSc). However, little is known of SSc specifically in Native Americans of the American Southwest. This study compared the clinical and serologic manifestations and outcomes of SSc in Native Americans and non-Native Americans (non-Natives) of this region. METHODS: This cross-sectional retrospective study included 137 SSc patients (109 [80%] were non-Native and 28 [20%] were Native Americans) followed over a mean of 11.5 ± 7.6 years. Participants were repetitively evaluated with medical history, physical examination, echocardiography, chest imaging, and serologic testing. Disease characteristics and outcomes were statistically compared between Native Americans and non-Native patients. RESULTS: The estimated prevalence of SSc in Native Americans was 40.0 cases/100 000 vs 17.1 cases/100 000 for non-Natives (odds ratio 2.34, 95% confidence interval [CI] 1.55-3.55, P < .001). The cohorts were similar in terms age, age of onset, limited vs diffuse cutaneous SSc, telangiectasias, gastroesophageal reflux disease, Raynaud phenomenon, serologies, interstitial lung disease, pulmonary arterial hypertension, scleroderma renal crisis, cancer prevalence, and overall mortality (all P > .05). However, for Native Americans, mortality specifically from fatal infections was 3.94-fold that of non-Natives (hazard ratio 6.88, 95% CI 1.37-34.64; P < .001). CONCLUSION: In Native Americans of the American Southwest, SSc is increased in prevalence but is phenotypically similar to SSc in non-Natives. However, mortality due specifically to infection is increased in Native Americans with SSc.