Diagnostic utility of urinalysis in detecting urinary tract infection in hemodialysis patients.

BACKGROUND/AIMS: Urinary tract infections (UTIs) are common in dialysis patients. The diagnostic accuracy of pyuria in this population has been incompletely evaluated and is the object of this study.

METHODS

We assembled a historical cohort of male hemodialysis patients with urinalysis and urine microbiology data. Each matched pair of urinalysis and urine culture was considered as the unit of measurement. We evaluated the diagnostic performance and plotted receiver operating characteristic curves for different cutoff values of pyuria [>5, >10, >50, >100 white blood cells per high-power field (WBC/HPF)].

RESULTS

Of 134 patients, 97 had at least one matched urinalysis and urine culture, providing 224 pairs for analysis. The prevalence of pyuria was 65 and 51% using cutoff values of >5 or >10 WBC/HPF, respectively. The presence of pyuria (>5 WBC/HPF) had a sensitivity between 82 and 89% and specificity of between only 53 and 55%. The presence of nitrites on dipstick had high specificity (94%) but very poor sensitivity (14-20%). All other urinary indices had poor diagnostic performance in the identification of a positive urine culture.

CONCLUSION

In the absence of adequate specificity and positive predictive value in dialysis patients, urine culture should be obtained to guide further treatment.