Accuracy of urinalysis in detection of urinary tract infection in a primary care setting

Aim : To determine the accuracy of urinalysis in the detection of urinary tract infection (UTI) in symptomatic patients at primary care level. Methods : A cross sectional study was undertaken on 100 patients with symptoms of UTI presenting at the Primary Care Clinic of University Malaya Medical Center, Kuala Lumpur, Malaysia during the months of August to November 1999. Their urine samples were tested simultaneously using urine dipstick, urine microscopy and urine culture. Urine culture was used as the gold standard and UTI was diagnosed when the urine culture showed a bacteria count of ≥ 10 5 organisms per mL. The sensitivity and specificity of each test was calculated. Results : The prevalence of UTI was 25% in symptomatic patients. The urine dipstick for leukocyte esterase, nitrite and red blood cell had sensitivities of 76, 56 and 76%, respectively. Their specificities were 60, 81 and 61%, respectively. Urine microscopy for leukocytes, red blood cells and bacterial count had sensitivities of 80, 52 and 84%, while their specificities were 76, 80 and 54%, respectively. Conclusion : The prevalence of UTI in the present study was low despite reported symptoms of UTI. Urinalysis is needed to support the diagnosis of UTI. In the present study, while there is accuracy in the urinalysis (as the sensitivities and specificities of various tests are comparable with other studies); lack of precision in each test because of the wide range of 95% confidence interval make it less reliable. Caution should be made in interpreting each test. „ 2003 Blackwell Publishing Asia and Wonca