Added value of clinical prediction rules for bacteremia in hemodialysis patients: An external validation study

Abstract

Introduction Having developed a clinical prediction rule (CPR) for bacteremia among hemodialysis (HD) outpatients (BAC-HD score), we performed external validation. Materials & methods Data were collected on maintenance HD patients at two Japanese tertiary-care hospitals from January 2013 to December 2015. We enrolled 429 consecutive patients (aged ≥ 18 y) on maintenance HD who had had two sets of blood cultures drawn on admission to assess for bacteremia. We validated the predictive ability of the CPR using two validation cohorts. Index tests were the BAC-HD score and a CPR developed by Shapiro et al. The outcome was bacteremia, based on the results of the admission blood cultures. For added value, we also measured changes in the area under the receiver operating characteristic curve (AUC) using logistic regression and Net Reclassification Improvement (NRI), in which each CPR was added to the basic model. Results In Validation cohort 1 (360 subjects), compared to a Model 1 (Basic Model) AUC of 0.69 (95% confidence interval [95% CI]: 0.59-0.80), the AUC of Model 2 (Basic model + BAC-HD score) and Model 3 (Basic model + Shapiro's score) increased to 0.8 (95% CI: 0.71-0.88) and 0.73 (95% CI: 0.63-0.83), respectively. In validation cohort 2 (96 subjects), compared to a Model 1 AUC of 0.81 (95% CI: 0.68-0.94), the AUCs of Model 2 and Model 3 increased to 0.83 (95% CI: 0.72-0.95) and 0.85 (95% CI: 0.76-0.94), respectively. NRIs on addition of the BAC-HD score and Shapiro's score were 0.3 and 0.06 in Validation cohort 1, and 0.27 and 0.13, respectively, in Validation cohort 2. Conclusion Either the BAC-HD score or Shapiro's score may improve the ability to diagnose bacteremia in HD patients. Reclassification was better with the BAC-HD score.