Metabolic and bariatric surgery (MBS) has been associated with weight reduction and obesity complications improvement. However, there is no clear evidence of the extent and consistency of the effects of this procedure on rheumatic diseases. This study aims to conduct a meta-analysis to address the impact of MBS on rheumatic diseases. We searched PubMed, Cochrane, and Embase for studies reporting the prevalence of rheumatic diseases, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the medication use after MBS. We conducted a random-effects meta-analysis using odds ratios (OR) and mean differences (MD) with 95% confidence intervals (CI). P-values <
0.05 were considered statistically significant. We included 28 studies comprising 43,421 patients, with 13,347 patients with rheumatic diseases. The prevalence of osteoarthritis (OA), rheumatoid arthritis, and psoriatic arthritis was significantly reduced after MBS (OR 0.20
95% CI 0.12 to 0.33
P = 0.01). The WOMAC index for patients with OA had a statistically significant overall reduction after MBS at 6 months (MD - 20.60 points
95% CI - 28.73 to - 12.47
P <
0.01) and at 12 months (MD - 15.88 points
95% CI - 19.09 to - 12.66
P <
0.01). Medication use significantly decreased after MBS, both at the follow-up beyond 2 years (OR 0.49
95% CI 0.35 to 0.69
P <
0.01) and up to 2 years (OR 0.32
95% CI 0.15 to 0.69
P <
0.01). In this meta-analysis, we found a significant decrease in the prevalence of rheumatic diseases, improvements in the WOMAC index, and reduced medication use among patients undergoing MBS.