Value of preoperative urine white blood cell and nitrite in predicting postoperative infection following percutaneous nephrolithotomy: a meta-analysis

BACKGROUND: To evaluate to what degree preoperative urine white blood cell (WBC) and urine nitrite (NIT) values are predictive of postoperative infections following percutaneous nephrolithotomy (PCNL). METHODS: A systematic literature search was performed of the PubMed, Embase, Cochrane Library, Wanfang Data, National Knowledge Infrastructure (CNKI), and China Science and Technology Journal Database (CSTJ or VIP) online databases to identify relevant studies that examined the predictive value of urine WBC or NIT as risk factors for post-PCNL infection, and the search was finished on February 28, 2020. Two independent reviewers screened the relevant studies, extracted necessary data from the eligible case-control studies (CCS), and assessed the quality of included studies through the Newcastle-Ottawa scale (NOS). RevMan 5.3 software and the Stata 16.0 software were used to complete the statistical analysis of data. Results are expressed as odds ratio (OR) with 95% confidence intervals (CIs). RESULTS: According to the statistical analysis of 12 eligible studies involving 6113 patients, positive urine WBC (WBC+: OR =3.86, 95% CI: 3.03–4.91, P<0.001) and positive NIT (NIT(+): OR =7.81, 95% CI: 5.44–11.21, P<0.001) in preoperative tests were identified as independent risk factors for postoperative infections following PCNL. CONCLUSIONS: In summary, as risk factors for postoperative infections, the presence of preoperative urine WBC+ and NIT+ should be evaluated as part of clinical procedure, in order to reduce infections of PCNL.