Do we have enough evidence to propose a urinary biomarker of bladder ischemia? A systematic review and meta-analysis

Objective Urinary bladder ischemia has been implicated in the pathogenesis of lower urinary tract symptoms (LUTS). However, research regarding urinary molecular markers for diagnosis and prognosis of pelvic ischemia is still premature, hindering further implementation in clinical practice. The aim of this study is to systematically appraise biomarkers associated with bladder ischemia detected in urine. Methods We performed a systematic review of PubMed/Medline, Embase, Web of Science, and the Cochrane Library in October 2021 according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. A subsequent reference search of retrieved articles was also performed. The identified reports were reviewed according to Systematic Review Center for Laboratory Animal Experimentation's risk-of-bias tool for animal studies. Results Eight publications were selected for this analysis. The included reports used 8-hydroxy-2 '-deoxyguanosine (8-OHdG) (in eight studies) as urinary marker of bladder ischemia. The pooled mean difference for urinary 8-OHdG levels between study and control groups was 13.73 ng/mg creatinine (95% CI, 9.79-17.67; P < .001; I-2 = 69%) for rat studies and 3.71 ng/mg creatinine (95% CI, 2.91-4.51; P < .001; I-2 = 94%) for rabbit studies. The result remained statistically significant favoring the control group independent of the type of intervention used to achieve bladder ischemia. Regarding secondary outcomes, mean voided volume and micturition interval were significantly lower in the ischemia group. Conclusion The lack of human randomized controlled trials is a major limitation. 8-OHdG is a urinary biomarker to be investigated in future studies for diagnosis and prognosis of LUTS in patients with vascular injury or bladder outlet obstruction.