Diagnostic performance of initial serum lactate for predicting bacteremia in female patients with acute pyelonephritis

Objectives The purpose of the present study was to investigate the diagnostic value of lactate for predicting bacteremia in female patients with acute pyelonephritis (APN). Methods We conducted a retrospective study of female patients with APN who visited the study hospital emergency department. The demographics, comorbidities, physiologies, and laboratory variables including white blood cell count and segmented neutrophil count, C-reactive protein, and initial serum lactate levels were collected and analyzed to identify associations with the presence of bacteremia. Results During the study period, a total of 314 patients were enrolled. One hundred twenty-three patients (39.2%) had bacteremia. Escherichia coli was the most frequent pathogen. Logistic regression analysis demonstrated that the lactate level was independently associated with the presence of bacteremia (odds ratio, 1.39 [95% confidence interval, 1.08-1.78]). The C-statistic of the lactate level was 0.67 (95% CI, 0.60-0.73). At a cutoff value of 1.4 mmol/L, the lactate level predicted bacteremia with a sensitivity (53.7%), specificity (72.3%), positive predictive value (55.5%), negative predictive value (70.8%), positive likelihood ratio (1.93), and negative likelihood ratio (0.64). Conclusion The initial serum lactate level showed poor discriminative performance for predicting bacteremia in female patients with APN.