Reducing unnecessary urine cultures through diagnostic stewardship is an effective way of reducing antibiotic treatment of patients with asymptomatic bacteriuria (ASB), according to findings of a 3-year quality improvement study conducted across the state of Michigan. “The believed mechanism behind diagnostic stewardship is that a positive test, regardless of the positive predictive value of that result, serves as a powerful nudge for action—in this case antibiotic treatment,” the authors write. “Thus, diagnostic stewardship works in part by reducing tests whose results are likely to be false positives.”
Hospitalized general care medicine patients at 46 hospitals participating in a collaborative quality initiative, the Michigan Hospital Medicine Safety Consortium, were included in the study. Facility staff could decide which antibiotic and diagnostic stewardship strategies to use. The main outcome measures were the change in percentage of patients with a positive urine culture who had ASB (diagnostic stewardship) and the change in percentage of patients with ASB who received antibiotics and antibiotic duration (antibiotic stewardship).
Between July 1, 2017, and Mar. 31, 2020, these changes were observed in those measures: “Of the 14,572 patients with a positive urine culture included in the study (median [IQR] age, 75.8 [64.2-85.1] years; 70.5% female), 28.4% (n = 4,134) had ASB, of whom 76.8% (n = 3,175) received antibiotics. Over the study period, the percentage of patients treated with antibiotics who had ASB (overall ASB-related antibiotic use) declined from 29.1% (95% CI, 26.2%-32.2%) to 17.1% (95% CI, 14.3%-20.2%) (adjusted odds ratio [aOR], 0.94 per quarter; 95% CI, 0.92-0.96). The percentage of patients with a positive urine culture who had ASB (diagnostic stewardship metric) declined from 34.1% (95% CI, 31.0%-37.3%) to 22.5% (95% CI, 19.7%-25.6%) (aOR, 0.95 per quarter; 95% CI, 0.93-0.97). The percentage of patients with ASB who received antibiotics (antibiotic stewardship metric) remained stable, from 82.0% (95% CI, 77.7%-85.6%) to 76.3% (95% CI, 68.5%-82.6%) (aOR, 0.97 per quarter; 95% CI, 0.94-1.01), as did adjusted mean antibiotic duration, from 6.38 (95% CI, 6.00-6.78) days to 5.93 (95% CI, 5.54-6.35) days (adjusted incidence rate ratio, 0.99 per quarter; 95% CI, 0.99-1.00).”
Editorial: “With evidence of a substantial reduction in antibiotic use in this and other studies, one must ask whether diagnostic stewardship should be more strongly encouraged by guidelines and government agencies,” editorialists write. “Interventions for diagnostic stewardship could be easily incorporated into existing infectious disease guidelines by the Infectious Diseases Society of America and others. Likewise, antimicrobial stewardship has grown largely through promotion by the Centers for Disease Control and Prevention and the Centers for Medicare & Medicaid Services. If these agencies were to systematically promote diagnostic stewardship as a method to reduce diagnostic error and antimicrobial resistance, practices would be more quickly disseminated.
“[These authors] identified diagnostic stewardship changes to urine culturing as the most effective interventions to reduce antibiotic use for ASB. Based on this work and others, we can expect that more hospitals will adopt diagnostic stewardship interventions to reduce inappropriate antibiotic use, decrease diagnostic error, and reduce rates of common [health care–associated infections].”