BACKGROUND: The diagnosis of urinary tract infection (UTI) is challenging among hospitalized older adults, particularly among those with altered mental status.

OBJECTIVE: To determine the diagnostic accuracy of procalcitonin (PCT) for UTI in hospitalized older adults.

DESIGN: We performed a prospective cohort study of older adults (≥65 years old) admitted to a single hospital with evidence of pyuria on urinalysis. PCT was tested on initial blood samples. The reference standard was a clinical definition that included the presence of a positive urine culture and any symptom or sign of infection referable to the genitourinary tract. We also surveyed the treating physicians for their clinical judgment and performed expert adjudication of cases for the determination of UTI.

PARTICIPANTS: Two hundred twenty-nine study participants at a major academic medical center.

MAIN MEASURES: We calculated the area under the receiver operating characteristic curve (AUC) of PCT for the diagnosis of UTI.

KEY RESULTS: In this study cohort, 61 (27%) participants met clinical criteria for UTI. The median age of the overall cohort was 82.6 (IQR 74.9-89.7) years. The AUC of PCT for the diagnosis of UTI was 0.56 (95% CI, 0.46-0.65). A series of sensitivity analyses on UTI definition, which included using a decreased threshold for bacteriuria, the treating physicians' clinical judgment, and independent infectious disease specialist adjudication, confirmed the negative result.

CONCLUSIONS: Our findings demonstrate that PCT has limited value in the diagnosis of UTI among hospitalized older adults. Clinicians should be cautious using PCT for the diagnosis of UTI in hospitalized older adults.