121 - Temporal Trends in Urine Culture Rates in the U.S. Acute Care Hospitals During 2012-2017

Background: Decreasing inappropriate urine cultures in hospitalized patients has been a target of diagnostic stewardship to improve infection surveillance and antimicrobial use. The impact of such efforts has been largely unstudied. This study assessed temporal trends in urine culture rates in a cohort of acute care hospitals (ACHs) between 2012 and 2017.Hospital Level Variation in Admission Urine Culture Rates
Hospital Level Variation in Post-admission Urine Culture Rates


Methods: We used microbiology data from ACHs participating in the Premier Healthcare Database and Cerner Health Facts to measure monthly urine culture rates. All cultures from the urinary tract collected on or before day 3 were defined as admission cultures (AC) and those collected on day 4 or later as post-admission cultures (PAC). Temporal trends in AC and PAC rates were estimated using general estimating equation models adjusting for hospital-level clustering, hospital size, teaching status, urban/rural designation, discharge month, and region.

Results: During the study period, ACHs had 20.8 million discharges and performed 4,946,717 urine cultures, of which 21% were PAC. In 2012 and 2017, the unadjusted AC rates were 18.7 and 18.4 per 100 discharges; the unadjusted PAC rates were 11.5 and 8.5 per 1,000 patient days (PD) respectively. The median annual hospital-level AC rate was 17.2 with inter-hospital variation ranging from 12.7 (quartile 1) to 24.1 (quartile 3) per 100 discharges, Figure 1. Similarly, the PAC rates varied among the ACHs with a median of 7.1 and inter-hospital variation ranging from 4.6 (quartile 1) to 10.5 (quartile 3) per 1,000 PDs, Figure 2. In multivariable analysis, no temporal trends in AC rates were detected (rate ratio (RR) 1.01; 95% confidence interval (CI): 0.99-1.02). However, PAC rates decreased 6.3% annually (RR 0.937; 95% CI: 0.93-0.95). Factors significantly associated (p< 0.02) with PAC rates were discharge month, teaching status, bed size, and region. For AC, significant associations (p< 0.0001) were discharge month and region.

Conclusion: Between 2012 and 2017, the rate of AC remained unchanged, but PAC rates decreased significantly. Factors driving this trend are unknown, but potential explanations include changes in culturing practices and/or decreases in hospital-onset urinary tract infections. Understanding factors related to the decrease and the impact on patient outcomes warrants further study.