Hair Loss After Metabolic and Bariatric Surgery: a Systematic Review and Meta-analysis

Background Hair loss is a common complication after metabolic and bariatric surgery (MBS). There is a lack of published systematic review in the scientific literature on this topic. The aim of this study was to perform a systematic review and meta-analysis on hair loss after MBS in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. Methods PubMed, CINAHL, EMBASE, Web of Science, SCOPUS, and four Chinese databases were searched. Data were pooled using Review Manager 5.3 and Stata 12.0, and subgroups were performed if necessary and feasible. Results A total of 18 studies (n = 2538) were included. The pooled results showed that the incidence of hair loss after MBS was 57% (95% CI 42-71%). It decreased with longer follow-up times. Hair loss was significantly more common in younger (mean difference (MD), - 2.45; 95% CI, - 4.26 to - 0.64; p = 0.008) women (OR, 3.87; 95% CI, 0.59 to 17.59; p = 0.08). Serum zinc (standardized mean difference (SMD), - 1.13; 95% CI, - 2.27 to 0.01, p = 0.05), folic acid (SMD = - 0.88, 95% CI - 1.29 to - 0.46, p < 0.0001), and ferritin levels (SMD, - 0.22; 95% CI, - 0.38 to - 0.05; p = 0.01), but not serum iron and vitamin B-12, were associated with hair loss following MBS. Conclusions Hair loss is common after MBS especially in younger women, and those with low serum levels of zinc, folic acid, and ferritin. Prospective studies on larger cohorts are needed.