Systematic reviews and meta-analyses on psoriasis: role of funding sources, conflict of interest and bibliometric indices as predictors of methodological quality

Background The quality of systematic reviews and meta-analyses on psoriasis, a chronic inflammatory skin disease that severely impairs quality of life and is associated with high costs, remains unknown. Objectives To assess the methodological quality of systematic reviews published on psoriasis. Methods After a comprehensive search in MEDLINE, Embase and the Cochrane Database (PROSPERO: CDR42016041611), the quality of studies was assessed by two raters using the Assessment of Multiple Systematic Reviews (AMSTAR) tool. Article metadata and journal-related bibliometric indices were also obtained. Systematic reviews were classified as low (0-4), moderate (5-8) or high (9-11) quality. A prediction model for methodological quality was fitted using principal component and multivariate ordinal logistic regression analyses. Results We classified 220 studies as high (17.2%), moderate (55.0%) or low (27.8%) quality. Lower compliance rates were found for AMSTAR question (Q)5 (list of studies provided, 11.4%), Q10 (publication bias assessed, 27.7%), Q4 (status of publication included, 39.5%) and Q1 (a priori design provided, 40.9%). Factors such as meta-analysis inclusion [odds ratio (OR) 6.22; 95% confidence interval (CI) 2.78-14.86], funding by academic institutions (OR 2.90, 95% CI 1.11-7.89), Article Influence score (OR 2.14, 95% CI 1.05-6.67), 5-year impact factor (OR 1.34, 95% CI 1.02-1.40) and article page count (OR 1.08, 95% CI 1.02-1.15) significantly predicted higher quality. A high number of authors with a conflict of interest (OR 0.90, 95% CI 0.82-0.99) was significantly associated with lower quality. Conclusions The methodological quality of systematic reviews published about psoriasis remains suboptimal. The type of funding sources and author conflicts may compromise study quality, increasing the risk of bias.