We should use a much higher leukocyte cutoff to diagnose UTI in older women

Référence

Bilsen MP, Aantjes MJ, van Andel E, et al. Current pyuria cutoffs promote inappropriate urinary tract infection diagnosis in older women. Clin Infect Dis 2023;76: 2070-2076.

Sommaire

The usual cutoffs for diagnosing urinary tract infection (UTI) are greater than 10 leukocytes/microliter (mcl) or greater than 5 to 10 leukocytes/high-powered field. However, these cutoffs were derived from studies of premenopausal women. Approximately 20% of older women have asymptomatic bacteriuria (ASB), and 90% of them also have some degree of pyuria. To identify the optimal leukocyte cutoff for a diagnosis of UTI in older women, these researchers identified 63 women, 65 years and older, with UTI based on a positive urine culture for a uropathogen, at least 2 lower urinary tract symptoms (LUTS), and at least 10 leukocytes/mcl. The comparison group consisted of 101 community-dwelling women, 65 years or older, without LUTS; 18 had ASB, 25 had a negative urine culture, and 58 had a culture with mixed flora. All urine samples underwent automated microscopy and urine flow cytometry. The area under the curve for leukocytes as a test for UTI was 0.93 for both methods. The optimal cutoff for automated microscopy was greater than 265 leukocytes/mcl, which was 88% sensitive and 88% specific (positive likelihood ratio [LR+] 7.2; negative likelihood ratio [LR-] 0.14). For flow cytometry, the optimal cutoff was greater than 231 leukocytes/mcl, which was 91% sensitive and 86% specific (LR+ 6.5; LR- 0.10). And what about the cutoff of greater than 10 leukocytes/mcl? It was 100% sensitive, but only 36% specific.