Sex-specific risk of anti-topoisomerase antibodies on mortality and disease severity in systemic sclerosis: 10-year analysis of the Leiden CCISS and EUSTAR cohorts

Background: We aimed to evaluate sex-specific risk of anti-topoisomerase I antibodies (ATA) on mortality, diffuse cutaneous systemic sclerosis, interstitial lung disease, and pulmonary hypertension in two cohorts of people with systemic sclerosis.

Methods: This study was a 10-year analysis of the prospective Leiden Combined Care in Systemic Sclerosis (CCISS) cohort in the Netherlands and the international European Scleroderma Trials and Research (EUSTAR) cohort. We included participants with systemic sclerosis according to the 2013 American College of Rheumatology-European League Against Rheumatism (ACR-EULAR) classification criteria; available autoantibody status; available skin subtyping; at least one available radiographic assessment of interstitial lung disease; and with a known date of disease onset. People with systemic sclerosis were categorised in six risk groups by sex and autoantibody status (anti-centromere antibody [ACA]-positive female, ACA-positive male, ACA and ATA-negative female, ACA and ATA-negative male, ATA-positive female, and ATA-positive male). We constructed Kaplan-Meier curves and Cox proportional hazard models, accounting for left-truncated survival to prevent bias because the date of disease onset (first non-Raynaud's symptom) preceded the date of cohort entry for all patients. The primary outcome was all-cause mortality and the secondary outcomes were diffuse cutaneous systemic sclerosis, interstitial lung disease, and pulmonary hypertension.

Findings: 445 (63%) of 708 participants between April 1, 2009, and Jan 1, 2022, in CCISS (101 [23%] male and 344 [77%] female) and 4263 (50%) of 8590 between June 1, 2004, and March 28, 2018, in EUSTAR (783 [18%] male and 3480 [82%] female) were eligible for this study. In both cohorts, ATA expression occurred significantly more often in males than in females (39 [39%] of 101 males vs 67 [19%] of 344 females in CCISS; p<0·0001 and 381 [49%] of 783 males vs 1323 [38%] of 3480 females in EUSTAR; p<0·0001). According to estimated survival rates, 30% of ATA-positive males versus 12% of ATA-positive females died in the CCISS cohort and 33% versus 15% died in the EUSTAR cohort within 10 years. After adjustment for age, race, and autoantibody status, male sex remained the most important risk factor for all-cause mortality (HR 2·9 [95% CI 1·5-5·5] in CCISS, p=0·0018; and HR 2·6 [2·0-3·4] in EUSTAR, p<0·0001).

Interpretation: We show that the association between male sex and increased mortality in systemic sclerosis cannot be explained by higher ATA prevalence. However, additional research on the effect of sex-specific characteristics on people with systemic sclerosis is required.

Funding: None.