Background/Purpose: Ectopic calcification, or calcinosis, is a common complication of scleroderma. However, a subset of scleroderma patients has a heavy burden of calcinosis, which may have unique risk factors compared to a light burden of calcinosis.

Methods: We determined calcinosis burden of patients in the Johns Hopkins Scleroderma Center cohort database through chart review. A heavy burden was defined as calcinosis deposits in three or more body areas excluding the hands and fingers, mass-like or bulky deposits, and/or sheet-like or plaque-like deposits on physician exam. A light burden was defined as calcinosis present but not meeting the criteria for heavy burden by chart review.  No calcinosis was defined as calcinosis recorded as absent in the Scleroderma Center database. We performed exploratory analyses comparing clinical, demographic, and serologic parameters by burden status. We then performed latent class analysis to identify scleroderma phenotypic classes followed by multinomial logistic regression to determine whether latent phenotypic classes and autoantibodies are independent risk factors for a light burden or a heavy burden of calcinosis.

Results: 29.4% (997/3388) of patients with scleroderma had calcinosis. 13.5% (130/963) had a heavy burden. The phenotypic class (Class 3 in Table 1) with predominantly diffuse skin disease as well as the greatest overall disease severity was associated with an increased risk of both a heavy burden of calcinosis (OR 6.29, 95% CI 3.42-11.57; p< 0.001) and a light burden of calcinosis (OR 2.71, 95% CI 2.01-3.65; p< 0.001) compared to the reference class with predominantly limited skin disease (Class 4).  The phenotypic class with predominantly sine skin disease (Class 1) was associated with a decreased risk of a light burden of calcinosis (OR 0.26, 95% CI 0.16-0.42; p< 0.001) compared to Class 4 but was not significantly associated with a high burden.  The phenotype with predominantly diffuse skin disease but less severe extra-cutaneous disease compared to Class 3 (Class 2) was not associated with either a light or heavy burden of calcinosis.  Autoantibodies to PM100 (OR 4.04, 95% CI 1.53 to 10.68; p=0.005) and PM75 (OR 3.07, 95% CI 1.23 to 7.68; p=0.024) were associated with an increased risk of a heavy burden of calcinosis.

Conclusion: Calcinosis burden may reflect cumulative scleroderma-related tissue damage. Independent of disease activity, autoantibodies to the PM/Scl complex are associated with a high burden of calcinosis, indicating the possibility of excess subclinical disease activity or aberrant tissue repair in patients with this unique immunologic response.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-heavy-burden-of-calcinosis-reflects-cumulative-disease-damage-in-scleroderma/