The 15% rule in scleroderma: the frequency of severe organ complications in systemic sclerosis. A systematic review.

Objective: The prevalence of organ complications in scleroderma (systemic sclerosis; SSc) varies by definition used. This study was done to determine the frequency of several features of SSc.
Methods: A search of Medline-Ovid/Embase, PubMed, and Scopus databases from 1980 to November 30, 2011, was conducted to identify relevant articles with at least 50 patients with SSc extracting prevalence of each organ complication. Study quality was assessed using the STROBE (Strengthening The Reporting of OBservational studies in Epidemiology) checklist. Pooled prevalence was calculated using the random effects method. Heterogeneity was quantified using I(2).
Results: A total of 5916 articles were identified (913 from Medline-Ovid/Embase, 1009 from PubMed, and 3994 from Scopus); 5665 were excluded, leaving 251 articles for full-text review, with 69 included. Where available, frequencies were also included from the Canadian Scleroderma Research Group. Many severe complications in SSc occur about 15% of the time, including cardiac involvement (15%, 95% CI 6-24), diastolic dysfunction (16%, 95% CI 14-17), estimated pulmonary artery pressure > 40 mm Hg (18%, 95% CI 14-21), pulmonary arterial hypertension by right heart catheterization (15%, 95% CI 12-17), forced vital capacity (FVC) < 70% predicted (15%, 95% CI 12-17), FVC < 80% predicted (17%, 95% CI 12-21), myositis (13%, 95% CI 10-17), inflammatory arthritis (12%, 95% CI 9-16), Sjögren overlap (13%, 95% CI 10-16), and digital ulcers (DU; 15%, 95% CI 10-20); and 15% of DU have complications (amputations 12%, 95% CI 8-16, and hospitalizations 13%, 95% CI 6-21). Scleroderma renal crisis is uncommon but occurs in almost 15% (12%, 95% CI 5-19) of cases of disseminated cutaneous SSc. There is no 15% rule within skin and gastrointestinal tract for SSc.
Conclusion: The "15%" rule for frequency of significant organ involvement in SSc is helpful.