Constitutional Symptoms Trigger Diagnostic Testing Before Antibiotic Prescribing in High-Risk Nursing Home Residents

To evaluate the use of diagnostic testing before treating an infection in nursing home (NH) residents suspected of having a urinary tract infection (UTI) or pneumonia.

Prospective longitudinal study nested within a randomized trial, using data from control sites.

Six NHs in southeast Michigan.

NH residents with an indwelling urinary catheter, enteral feeding tube, or both (N = 162) with 695 follow-up visits (189 (28%) visits with an infection).

Clinical and demographic data-including information on incident infections, antibiotic use, and results of diagnostic tests-were obtained at study enrollment, after 14 days, and monthly thereafter for up to 1 year.

One hundred (62%) NH residents had an incident infection requiring antibiotics, with substantial variations between NHs. In addition to presence of infection-specific symptoms, change in function was a significant predictor of ordering a chest X-ray to detect pneumonia (odds ratio (OR) = 1.7, P = .01). Similarly, change in mentation was a significant predictor of ordering a urinalysis (OR = 1.9, P = .02), chest X-ray (OR = 3.3, P < .001), and blood culture (OR = 2.3, P = .02). Antibiotics were used empirically, before laboratory results were available, in 50 of 233 suspected cases of UTI (21.5%) and 16 of 53 (30.2%) suspected cases of pneumonia. Antibiotics were used in 17% of visits without documented clinical or laboratory evidence of infection.

Constitutional symptoms such as change in function and mentation commonly lead to diagnostic testing and subsequent antibiotic prescribing. Antibiotic use often continues despite negative test results and should be a target for future interventions.