Background/Purpose: Calcinosis is a sequelae of juvenile and adult dermatomyositis (DM) associated with significant morbidity and poor quality of life. It is hypothesized that inflammatory vasculopathy may lead to dystrophic mineral deposition. Apolipoprotein A-I (apoA-I) is the major apolipoprotein component of HDL which normally prevents inflammation in the vessel wall. The current study aims to identify clinical and laboratory features associated with calcinosis in a cohort of adult patients with idiopathic inflammatory myopathies (IIM).

Methods: A cross sectional study was performed in 288 adult patients with IIM recruited at the University of California, Los Angeles between 2008-2020. Clinical and laboratory features including myositis autoantibodies were compared between patients with and without calcinosis. HDL-associated ApoA-I levels (HDL-apoA-I) were measured using sandwich ELISA. Patients were divided into HDL-apoA-I tertiles to compare the association of calcinosis with low (tertile 1) vs high (tertial 3) HDL-apoA-I. Stepwise multivariate logistic models were constructed to obtain odds ratios (ORs) that related calcinosis to various variables. Statistically significant bivariate variables were considered as predictors for the stepwise model. The final stepwise model was selected to minimize the Bayes Information Criterion (BIC).

Results: We identified 27 (9.3%) patients with calcinosis in our IIM cohort. All patients with calcinosis had dermatomyositis (DM), (12.6 % of DM cohort with calcinosis), with the exception of 1 patient who had polymyositis overlap with CREST syndrome. Five (19%) of the patients with calcinosis had juvenile onset DM. Patients with calcinosis were older and had significantly longer disease duration, higher MD global damage scores and lower total cholesterol (TC), LDL-cholesterol (LDL-C), and CPK levels. Among myositis autoantibodies, NXP2, SAE and PM-scl ab were more frequently seen in patients with calcinosis. In contrast, antisynthetase, HMGCR and SRP ab were less frequently seen in patients with calcinosis. None of the patients with calcinosis had a history of cancer compared to 28% in patients without calcinosis. Low (vs high) HDL-apoA-I levels were associated with calcinosis, and the association remained strong in multivariate analysis in addition to older age and longer disease duration. In fact, IIM patients with low HDL-apoA-I were 11.5 times more likely to have calcinosis compared to patients with high HDL-apoA-I.

Conclusion: 12.6 % of dermatomyositis patients had calcinosis in our IIM cohort, which associated with older age, longer disease duration, and lower HDL-apoA-I levels. Further studies are warranted to evaluate the role of apoA-I in the development of calcinosis in patients with dermatomyositis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/lower-hdl-associated-apolipoprotein-a-i-levels-associate-with-presence-of-calcinosis-in-adult-dermatomyositis/