The role of bladder microbiota in urinary diseases and cytokine production: a systematic review and meta-analysis

Purpose: The literature examining the relationship between bladder microbiota and urinary diseases and their effect on cytokine production was evaluated through a systematic review and meta-analysis.Methods :The study was designed according to PRISMA criteria. Google Scholar and PubMed electronic databases were searched, and potential studies were selected according to inclusion/exclusion criteria. Studies were included in the meta-analysis using a random effects model. The Newcastle–Ottawa Scale (NOS) was used for bias assessment.Result: Results Of the 46 studies included, 12 case-control studies covering the years 2019-2025 were deemed suitable for analysis. Most studies were conducted in China and the USA. In the meta-analysis evaluating the relationship between microbiota and disease, the combined effect size was found to be MD = 1.30 (95% CI: -2.18 – 4.78) and was not statistically significant (Z = 0.73; p = 0.46). Heterogeneity is at a very high level. In the meta-analysis regarding cytokine production, the combined analysis result was found to be MD= 21.05 (95% CI: -9.67–51.77), and this difference was not statistically significant (Z = 1.34, p = 0.18). A very high level of heterogeneity was detected among the studies.Conclusion: The included studies have moderate to high methodological quality, and the reliability of the findings is at an acceptable level. The current data are insufficient to draw a definitive conclusion about the effectiveness of the approach evaluated. To obtain stronger evidence, advanced studies with larger sample sizes, using standardized methods, and reporting data suitable for meta-analysis are needed.