Background: Approximately 1-2% of the U.S. population gets community-acquired pneumonia (CAP) annually in the U.S. and CAP is associated with substantial mortality, morbidity and costs. While the incidence of CAP is well-defined, the incidence of outpatients who fail antibiotics and eventually become hospitalized is less clear. The objective of this study was to provide real-world data on hospitalization rates and costs associated with CAP after an initial outpatient visit and antibiotic course of therapy for CAP.
Methods: Study was a retrospective claims analysis using MarketScan® Commercial & Medicare Databases. Key inclusion criteria included age ≥18 years old, outpatient visit for CAP (based on ICD-9-CM codes) between 2011 and 2015 and monotherapy antibiotic pharmacy claim for one of the following drug classes: macrolides, fluoroquinolones, beta-lactams or tetracyclines. Treatment was considered a failure if one of the following events occurred within 30 days: (1) antibiotic refill, (2) antibiotic switch, (3) ER visit or (4) hospitalization. Adjusted failure rates controlling for age, sex, CDC census region, and health plan design were obtained using logistic regression. Costs data represent the total dollars paid to the provider (payer + copayment + coinsurance + deductible + coordination of benefits) and were inflated to 2016 U.S. dollars using the medical component of the Consumer Price Index.
Results: 251,947 adult outpatients met inclusion criteria. Mean age was 52.2 years with 47.7% male and 21.5% Medicare enrollees. The most common comorbidities were chronic pulmonary disease (18.1%), diabetes (11.5%) and asthma (9.0%). The majority of patients were prescribed azithromycin (n=101,492, 40.3%) followed by levofloxacin (n=95,019, 37.7%). Total antibiotic failure rate was 22.1% (n=55,741/251,947) and comprised of: antibiotic refill (n=11,493/55,741, 20.6%), antibiotic switch (n=39,397/55,741, 70.7%), ER visit (n=1,835/55,741, 3.3%) and hospitalization (n=3,015/55,741, 5.4%). The highest rate of antibiotic failure was seen in the beta-lactam (25.7%) cohort while the lowest antibiotic failure rate was seen in the fluoroquinolone (20.8%) cohort (p<0.0001). Antibiotic failure resulting in hospitalization led to the highest per-patient cost (mean=$26,867, sd=$54,199), followed by ER visit (mean=$3,927, sd=$11,735), antibiotic refill (mean=$648, sd=$8,415) and antibiotic switch (mean=$599, sd=$4,774) (p<0.0001). Among treatment failures who were hospitalized for CAP, mean length of hospital stay was 5.64 days (sd=7.75). Finally, among all treatment failure patients, 18.1% died within 30 days compared to 4.6% of non-treatment failures (p<0.0001).
Conclusions: Nearly 1 in 4 CAP patients treated with the most commonly used antibiotics fail their initial therapy, 18.1% of which die within 30 days, demonstrating a significant unmet need in the treating of this common infectious disease.