Abstract
OBJECTIVE: Systemic sclerosis (SSc) is associated with several specific risk factors for fracture due to the complications of the disease and related medications. The present study was undertaken to examine the relationship between SSc-associated clinical features and fracture rate in a large US cohort. METHODS: Participants with SSc in FORWARD, The National Databank for Rheumatic Diseases, were included (1998-2019). Age- and sex-matched individuals with osteoarthritis (OA) from the same database were included as comparators. The primary end point was self-reported major osteoporotic fracture. Cox proportional hazards models were used to study the associations between risk factors and fractures. RESULTS: The study included 922 individuals (SSc patients, n = 154; OA patients, n = 768). Eighty-seven percent were female, with a mean age of 57.8 years. Fifty-one patients developed at least 1 fracture during a median of 4.2 years (0.5-22.0 years) of follow-up. Patients with SSc had more frequent fractures compared to OA comparators (hazard ratio [HR] 2.38 [95% confidence interval (95% CI) 1.47-3.83]). Among patients with SSc, a higher Rheumatic Disease Comorbidity Index score (HR 1.45 [95% CI 1.20-1.75]) and a higher Health Assessment Questionnaire disability index score (HR 3.83 [95% CI 2.12-6.93]) were associated with more fractures. Diabetes mellitus (HR 5.89 [95% CI 2.51-13.82]) and renal disease (HR 2.43 [95% CI 1.10-5.37]) were independently associated with fracture among SSc patients relative to SSc patients without these comorbidities. CONCLUSION: Our findings highlight factors associated with fracture among patients with SSc. Disability as measured by the HAQ DI is a particularly strong indicator of fracture rate in SSc. Improving SSc patients' functional status, where possible, may lead to better long-term outcomes.