Influence of gender on the performance of urine dipstick and automated urinalysis in the diagnosis of urinary tract infections at the emergency department.

BACKGROUND Urinary tract infections (UTIs) are frequently encountered at the Emergency Department (ED). Given the anatomical differences between men and women, we aimed to clarify differences in the diagnostic performance of urinary parameters at the ED. METHODS A cohort study of adults presenting at the ED with fever and/or clinical suspected UTI. Performance of urine dipstick (UD) and automated urinalysis (UF-1000i) were analysed for the total study population and men and women separately. We focused on 1) UTI diagnosis and 2) positive urine culture (UC, ≥105 CFU/ml) as outcome. RESULTS In 360 of 917 cases (39.3%) UTI was established (men/women 35.1%/43.6%). Diagnostic accuracy of UD was around 10% lower in women compared to men. Median automated leucocyte and bacterial count were higher in women compared to men. Diagnostic performance by receiver operating analysis was 0.851 for leucocytes (men/women 0.879/0.817) and 0.850 for bacteria (men/women 0.898/0.791). At 90% sensitivity, cut-off values of leucocyte count (men 60/µL, women 43/µL), and bacterial count (men 75/µL, women 139/µL) showed performance differences in favour of men. In both men and women, diagnostic performance using specified cut-off values was not different between normal and non-normal bladder evacuation. UC was positive in 327 cases (men/women 149/178), as with UTI diagnosis, diagnostic values in men outperformed women. CONCLUSIONS Overall diagnostic accuracy of urinary parameters for diagnosing UTI is higher in men. The described differences in cut-off values for leukocyte and bacterial counts for diagnosing UTI necessitates gender-specific cut-off values, probably reflecting the influence of anatomical and urogenital differences.