Prognostic Ability of Nutritional Indices for Outcomes of Bladder Cancer: A Systematic Review and Meta-Analysis

Background: Nutrition has become an important parameter influencing the prognosis of several cancers. However, its impact on outcomes for bladder cancer (BC) is still unclear. This review examines the association between three commonly used nutritional indices, namely, the prognostic nutritional index (PNI), controlling nutritional status (CONUT), and the geriatric nutritional risk index (GNRI) and outcomes of BC. Methods: PubMed, CENTRAL, Scopus, Web of Science, Embase, and Google Scholar were explored for studies published up to April 13, 2023. Data from studies were pooled to examine the association between PNI, CONUT, or GNRI and overall survival (OS) and recurrence-free survival (RFS). Results: Thirteen studies were included. Meta-analysis demonstrated significantly poor OS with low PNI versus high PNI in BC patients (hazard ratio [HR]: 1.71; 95% confidence interval [CI]: 1.37, 2.14; I2 = 0%). This result remained significant in various subgroup analyses. However, no association was noted between PNI and RFS (HR: 1.22; 95% CI: 0.67, 2.24; I2 = 84%). Meta-analysis showed that patients with high CONUT scores had significantly poor OS (HR: 2.43; 95% CI: 1.82, 3.25; I2 = 0%) as well as RFS (HR: 2.90; 95% CI: 2.10, 4.01; I2 = 0%). Data on GNRI were scarce and conflicting. Conclusion: Limited data show that PNI and CONUT are predictive of outcomes in BC. Low PNI was associated with poor OS, while high CONUT was associated with poor OS and RFS. Data on GNRI are too scarce to obtain conclusions. Further studies are needed to supplement the results.