Purpose: Systemic sclerosis (SSc) is a chronic connective tissue disorder characterized by skin thickening with vascular and visceral involvements. The efficacy of cyclophosphamide for SSc-related skin fibrosis remains controversial. The aim of this study was to evaluate the effectiveness of cyclophosphamide for skin fibrosis in SSc.
Methods: PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov databases were systematically searched for all published clinical trials on the treatment of SSc with cyclophosphamide until January 15, 2025.The outcome of interest was the extent of skin fibrosis, measured by the modified Rodnan skin score (mRSS). Two authors independently screened studies, extracted data, and evaluated the risk of bias. Meta-analysis was conducted with Stata/SE software.
Results: A total of 20 articles involving 869 patients met the inclusion criteria. Cyclophosphamide reduced mRSS score by 2.30 (95% CI 0.72-3.88), 4.53 (95% CI 2.91-6.14), 6.72 (95% CI 2.74-10.70), 5.70 (95% CI 4.04-7.36), and 4.60 (95% CI 3.18-6.02) at 6-, 12-, 18-, 24- and 36-month, respectively. The estimated effect size, obtained by pooling mRSS from all studies at the follow-up endpoint, decreased by 4.71 (95% CI 2.72-6.70). In diffuse cutaneous SSc (dcSSc) subtype, the pooled mRSS decreased by 3.02 (95% CI 1.46-4.58), 6.45 (95% CI 5.02-7.87), 8.03 (95% CI 5.26-10.80), and 6.34 (95% CI 6.00-6.68) at 6-, 12-, 18-, and 24-month, respectively. And the overall reduction in mRSS at the end of follow-up in dcSSc was 7.30 (95% CI 5.61-8.99) across 11 studies. Significant heterogeneity was observed among these studies, and subgroup analysis revealed that study size and disease subtype partially explained the heterogeneity. Sensitivity analysis indicated good study stability.
Conclusion: Cyclophosphamide effectively reduced mRSS scores in SSc, particularly in dcSSc. While skin thickness improvement diminishes after 24 months, it remains a viable option for patients with worsening skin fibrosis.
Trial registration: PROSPERO registration number: CRD42024502283. Registered on 25 January 2024.