Development of a risk score for predicting urine culture using white blood cell, nitrite, and leukocyte esterase for Rational Laboratory Use at Sisaket Hospital.

Abstract

This retrospective descriptive research aimed to evaluate the efficiency and correlation of white blood cells (WBC), nitrite, and leukocyte esterase (LE) to develop a risk scoring system for predicting urine culture (UC) results. Additionally, it evaluated the effectiveness of this scoring system in promoting rational laboratory use (RLU) policies.

The study was conducted on 330 samples collected between September 2024 and August 2025. Data collection tools included computer programs (hospital information system: HIS; laboratory information system: LIS; microbiology laboratory: MLAB), automated analyzers (urine analysis and urine culture), and data recording forms. Statistical analysis was performed using descriptive statistics and inferential statistics, specifically multiple logistic regression. The data collection of this study was from December 2025 to June 2026.

The results showed that the majority of the samples were from males, with a mean age of 57.04 years; the prevalence of a positive UC rate was 34.85%, and LE demonstrated the highest sensitivity at 90.43%, while nitrite showed the highest specificity at 97.21%. Including nitrite-positive and LE 2+ were significantly associated with positive UC results (p < 0.001), whereas WBC showed no significant correlation (multivariate). The developed risk score reached an optimal cut-off point of 1. Implementing the RLU policy based on this score could reduce unnecessary UC testing, saving an estimated 657,000 THB per year. Furthermore, it helps reduce inappropriate antibiotic use and antimicrobial resistance, ensures high-risk patients receive timely treatment, and minimizes complications.

In conclusion, hospitals can utilize these findings as a clinical decision-making guideline for ordering urine cultures, specifically when nitrite is positive and/or LE is ≥ 2+.