Burden of Ambulatory Visits and Antibiotic Prescribing Patterns for Adults With Community-Acquired Pneumonia in the United States, 1998 Through 2009

Community-acquired pneumonia (CAP) is commonly managed in ambulatory settings, yet little is known about trends in ambulatory visit rates or antibiotic prescribing for CAP in adults in the United States. The Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS)¹ published guidelines for CAP management in 2007. These guidelines¹ recommend a macrolide or doxycycline for previously healthy ambulatory patients with CAP. Fluoroquinolone monotherapy or a β-lactam–macrolide combination are recommended for patients with comorbid conditions or risk factors for drug-resistant Streptococcus pneumoniae infection.

We estimated US adult ambulatory CAP visit rates and described antibiotic prescribing patterns for CAP. We also examined associations between patient and visit characteristics and antibiotic selection to assess concordance with IDSA/ATS guidelines.

We used 1998 through 2009 data from the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS), 2 annual surveys of ambulatory patient encounters in the United States.² Adults at least 18 years of age with a primary International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of pneumonia or a primary diagnosis of fever or cough and a secondary diagnosis of pneumonia, empyema, or pleurisy were considered to have CAP.³ Patients with concurrent bacterial illnesses and those requiring hospitalization were excluded from the prescribing analysis.

We used adjusted patient weights and age-specific and year-specific census estimates to calculate CAP visit rates for 6 periods of 2 years. We assessed trends in antibiotic selection using logistic regression analysis. To assess whether patient comorbid conditions were associated with receipt of a fluoroquinolone or a β-lactam–macrolide combination, as recommended by the IDSA/ATS guidelines, we used multivariable logistic regression analysis to assess patient and physician visit characteristics associated with receipt of these regimens. All statistical analyses were performed using Stata software, version 11 (StataCorp).

An estimated 37 million visits occurred during the study period. Average annual visit rates were 12.6 to 15.7 visits per 1000 persons (Figure) and were highest among persons 65 years or older.

Antibiotics were prescribed at 61% of CAP visits (Table); a single medication made up 88% of regimens. Fluoroquinolone treatment increased from 18% of regimens during 1998 to 1999 to 35% during 2008 to 2009 (P for trend, .01). Treatment with β-lactams decreased from 36% of regimens in 1998 to 1999 to 18% in 2008 to 2009 (P for trend, .02). No statistically significant associations were found between age, sex, race, presence of chronic comorbid conditions, insurance status, obtaining a chest radiograph, or tobacco use and receipt of fluoroquinolone monotherapy or a β-lactam–macrolide combination.

We found no significant change in the burden of ambulatory CAP visits in the United States between 1998 and 2009. However, fluoroquinolone prescribing for CAP increased dramatically. Although β-lactams have not been recommended for CAP treatment since 2001,⁴ they still constituted 18% of regimens. Selection of fluoroquinolone monotherapy or a β-lactam–macrolide combination was not associated with the presence of comorbid conditions, as recommended by the IDSA/ATS CAP guidelines.

Convenient dosing may contribute to the popularity of fluoroquinolones, which has been documented elsewhere for other conditions.⁵ Because CAP treatment decisions are usually made empirically, physician preference may drive antibiotic selection. However, because indiscriminate use of antibiotics may select for resistance,⁶ reserving fluoroquinolones for specific indications may be important for preventing the development of resistance to this important class of antibiotics.

Because no specific diagnostic code for CAP exists, some patients may have been misclassified. In addition, we were unable to distinguish between diagnostic and follow-up visits, so both were likely included in our sample. Consideration of all comorbidities was not possible with data from the NAMCS and NHAMCS. Nonetheless, efforts to understand antibiotic selection are needed to inform efforts to promote guideline-concordant therapy. Improving guideline implementation will preserve the utility of fluoroquinolones for the patients who need them most, improving health care quality and reducing unnecessary variation in care.

Corresponding Author: Jonathan M. Wortham, MD, 1600 Clifton Rd, NE MS E-10, Atlanta, GA 30333 (vij5@cdc.gov).

Published Online: July 28, 2014. doi:10.1001/jamainternmed.2014.3456.

Author Contributions: Dr Wortham and Mr Shapiro had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: All authors.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Wortham, Hicks.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Shapiro, Hersh,

Administrative, technical, or material support: Wortham.

Study supervision: Hersh, Hicks.

Conflict of Interest Disclosures: None reported.

Funding/Support: This work was supported by funding from the Centers for Disease Control and Prevention.

Role of the Sponsor: The Centers for Disease Control and Prevention had no role in the design and conduct of the study; analysis and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.