Lower urinary tract symptoms (LUTS) are highly prevalent and impose a significant clinical burden. Metabolic syndrome (MetS) has been proposed as a potential risk factor, but previous findings are inconsistent due to methodological variability. We aimed to systematically synthesize and quantify the association between MetS and LUTS severity measured by the International Prostate Symptom Score (IPSS).

Following PRISMA guidelines (PROSPERO: CRD420251181500), we searched PubMed, Scopus, Web of Science, Embase, and Cochrane up to 2024. Cross-sectional studies examining MetS (by established criteria) and LUTS were included. Two reviewers independently performed screening, data extraction, and JBI quality assessment. Pooled standardized mean differences (SMD) were calculated using random-effects models due to high heterogeneity.

Of 11,174 records, 80 studies (58,262 participants) were included in qualitative synthesis, and 33 studies in IPSS meta-analysis. MetS was significantly associated with higher IPSS scores (SMD = 0.41, 95% CI: 0.10 to 0.72, p = 0.01). However, heterogeneity was substantial (I² = 98.64%). Subgroup analysis by LUTS severity (37 studies) showed that this association was driven by severe LUTS (OR = 1.37, 95% CI: 1.17 to 1.61), whereas mild (OR = 0.78) and moderate (OR = 0.73) LUTS were not significant. Storage symptoms showed the strongest association (SMD = 0.52, p < 0.001). GRADE certainty was low.

This meta-analysis shows a significant association between metabolic syndrome (MetS) and increased LUTS severity, with a moderate effect size. Notably, this relationship is driven primarily by severe LUTS, while no significant association was observed in mild or moderate cases, suggesting that MetS may contribute more to symptom progression than initiation. The stronger link with storage symptoms supports potential mechanisms such as inflammation, ischemia, and autonomic dysfunction affecting bladder function. However, the very high heterogeneity and low certainty of evidence limit the robustness of these findings. Additionally, the cross-sectional design precludes causal inference. Overall, MetS appears to be an important modifier of LUTS severity, particularly in more advanced cases, supporting the role of metabolic evaluation in these patients.

MetS is significantly associated with more severe LUTS, particularly storage symptoms and severe clinical presentations. These findings support routine metabolic assessment in LUTS patients, though high heterogeneity and cross-sectional design preclude causal inference.