Simulated Adoption of 2019 Community-Acquired Pneumonia Guidelines Across 114 Veterans Affairs Medical Centers: Estimated Impact on Culturing and Antibiotic Selection in Hospitalized Patients

Abstract

Background: The 2019 American Thoracic Society/Infectious Diseases Society of America guidelines for community-acquired pneumonia (CAP) revised recommendations for culturing and empiric broad-spectrum antibiotics. We simulated guideline adoption in Veterans Affairs (VA) inpatients.

Methods: For all VA acute hospitalizations for CAP from 2006-2016 nationwide, we compared observed with guideline-expected proportions of hospitalizations with initial blood and respiratory cultures obtained, empiric antibiotic therapy with activity against methicillin-resistant Staphylococcus aureus (anti-MRSA) or Pseudomonas aeruginosa (antipseudomonal), empiric "overcoverage" (receipt of anti-MRSA/antipseudomonal therapy without eventual detection of MRSA/P. aeruginosa on culture), and empiric "undercoverage" (lack of anti-MRSA/antipseudomonal therapy with eventual detection on culture).

Results: Of 115 036 CAP hospitalizations over 11 years, 17 877 (16%) were admitted to an intensive care unit (ICU). Guideline adoption would slightly increase respiratory culture (30% to 36%) and decrease blood culture proportions (93% to 36%) in hospital wards and increase both respiratory (40% to 100%) and blood (95% to 100%) cultures in ICUs. Adoption would decrease empiric selection of anti-MRSA (ward: 27% to 1%; ICU: 61% to 8%) and antipseudomonal (ward: 25% to 1%; ICU: 54% to 9%) therapies. This would correspond to greatly decreased MRSA overcoverage (ward: 27% to 1%; ICU: 56% to 8%), slightly increased MRSA undercoverage (ward: 0.6% to 1.3%; ICU: 0.5% to 3.3%), with similar findings for P. aeruginosa. For all comparisons, P < .001.

Conclusions: Adoption of the 2019 CAP guidelines in this population would substantially change culturing and empiric antibiotic selection practices, with a decrease in overcoverage and slight increase in undercoverage for MRSA and P. aeruginosa.

Keywords: empiric therapy; guideline; pneumonia.

Figure 1.

Observed versus guideline-expected culturing and empiric antibiotic selection practices. Each plot depicts the proportion of hospitalizations with the indicated practice. Markers connected by colored lines represent proportions at the facility level under observed (closed dots, •) and guideline-expected (open diamonds, ◊) conditions. Adjacent boxplots depict the variability in these proportions, with median facility proportion labeled. For all observed-guideline proportion comparisons, P < .001 by Cochran-Mantel-Haenszel tests with stratification by facility. Abbreviations: ICU, intensive care unit; MRSA, methicillin-resistant Staphylococcus aureus; PA, Pseudomonas aeruginosa.

Figure 2.

Reclassification of observed versus guideline-expected culturing and MRSA/PA case detection in hospital wards. (A, B) Contingency 2 × 2 tables between observed and guideline-expected respiratory and blood culturing. Insets show respective results for observed sent cultures. (C, D) Contingency 2 × 2 tables between observed and guideline-expected case detection of MRSA and PA by combined respiratory and blood culture results. Since observed-absent guideline-expected-present cultures are theoretical, the case detection from these is unknown and marked by “NA”. Abbreviations: MRSA, methicillin-resistant Staphylococcus aureus; PA, Pseudomonas aeruginosa.