Pneumococcal Urinary Antigen Testing in United States Hospitals: A Missed Opportunity for Antimicrobial Stewardship

Abstract

Background: The Infectious Diseases Society of America recommends pneumococcal urinary antigen testing (UAT) when identifying pneumococcal infection would allow for antibiotic de-escalation. However, the frequencies of UAT and subsequent antibiotic de-escalation are unknown.

Methods: We conducted a retrospective cohort study of adult patients admitted with community-acquired or healthcare-associated pneumonia to 170 US hospitals in the Premier database from 2010 to 2015, to describe variation in UAT use, associations of UAT results with antibiotic de-escalation, and associations of de-escalation with outcomes.

Results: Among 159 894 eligible admissions, 24 757 (15.5%) included UAT performed (18.4% of intensive care unit [ICU] and 15.3% of non-ICU patients). Among hospitals with ≥100 eligible patients, UAT proportions ranged from 0% to 69%. Compared to patients with negative UAT, 7.2% with positive UAT more often had a positive Streptococcus pneumoniae culture (25.4% vs 1.9%, P < .001) and less often had resistant bacteria (5.2% vs 6.8%, P < .05). Of patients initially treated with broad-spectrum antibiotics, most were still receiving broad-spectrum therapy 3 days later, but UAT-positive patients more often had coverage narrowed (38.4% vs 17.0% UAT-negative and 14.6% untested patients, P < .001). Hospital rate of UAT was strongly correlated with de-escalation following a positive test. Only 3 patients de-escalated after a positive UAT result were subsequently admitted to ICU.

Conclusions: UAT is not ordered routinely in pneumonia, even in ICU. A positive UAT result was associated with less frequent resistant organisms, but usually did not lead to antibiotic de-escalation. Increasing UAT and narrowing therapy after a positive UAT result are opportunities for improved antimicrobial stewardship.

Keywords: antimicrobial stewardship; community-acquired pneumonia; urinary antigen testing.

Figure 1.

Hospital rates of pneumococcal urinary antigen testing (UAT). Distribution of hospitals across binned proportions of UAT utilization among patients admitted with pneumonia and undergoing blood or respiratory (including sputum) culture or UAT within 2 days of hospitalization. Hospitals reporting <100 such patients, reporting on 2.8% of such patients, are excluded. Data include 159 353 patients from 164 hospitals, including hospitals with ≥100 patients. Sixty-five (39.6%) hospitals did not have any UAT ordered.

Figure 2.

Time trends in urinary antigen testing (UAT) ordering and results. Proportion (percentages) of patients undergoing UAT and fraction of positive UAT results among patients admitted with pneumonia and undergoing blood or respiratory (including sputum) culture or UAT within 2 days of hospitalization.

Figure 3.

Resistance to community-acquired pneumonia (CAP) therapy. Proportions (percentages) of patients undergoing urinary antigen testing (UAT), and blood or respiratory (including sputum) culture within 2 days of hospitalization, who had organisms resistant to CAP therapy, by UAT result and source of positive culture.

Figure 4.

Proportion of patients de-escalated by urinary antigen testing (UAT) result and hospital proportion of patients undergoing UAT. The symbols connected by straight lines show the proportions de-escalated in bins of hospitals whose UAT proportions fall respectively within ranges from 0–10% to 60%–70% with intermediate intervals, each of 10% width, centered on their midpoints, for patients with positive (triangles) and negative (circles) UAT results. The dashed lines without symbols show restricted cubic spline fits from a generalized linear mixed binomial regression model with identity link function, fixed effects of UAT result, observed hospital UAT proportion and their interaction, and random hospital effects.