Cost effectiveness of adherence to IDSA/ATS guidelines in elderly patients hospitalized for Community-Aquired Pneumonia.

BACKGROUND: Adherence to guidelines for the treatment of hospitalized elderly patients with community-acquired pneumonia (CAP) has been associated with improved clinical outcomes. This study evaluated the cost-effectiveness of adherence to guidelines for the treatment of CAP in an elderly hospitalized patient cohort.

METHODS: Data from an international, multicenter observational study for patients age 65 years or older hospitalized with CAP from 2001 to 2007 were used to estimate transition probabilities for a multi-state Markov model traversing multiple health states during hospitalization for CAP. Empiric antibiotic therapy was classified as adherent, over-treated, and under-treated according to 2007 Infectious Disease Society of America/American Thoracic Society IDSA/ATS guidelines. Utilities were estimated from an expert panel of active clinicians. Costs were estimated from a tertiary referral hospital and adjusted for inflation to 2013 US dollars. Costs, utilities, and transition probabilities were all modeled using probability distributions to handle their inherit uncertainty. Cost-effectiveness analysis was based on the first 14 days of hospitalization. Patients admitted to the intensive care unit (ICU) were analyzed separately from those admitted to the ward. Sensitivity analyses with regards to time frame (out to 30 days hospitalization), cost estimates, and willingness to pay values were performed.

RESULTS: The model parameters were estimated using data from 1635 patients (1438 admitted to the ward and 197 admitted to the ICU). For the ward model, adherence to antibiotic guidelines was the dominant strategy and associated with lower costs (-$1379 and -$799) and improved quality of life compared to over- and under-treatment. In the ICU model, however, adherence to guidelines was associated with greater costs (+$13,854 and + $3461 vs. over- and under-treatment, respectively) and lower quality of life. Acceptance rates across the willingness to pay ranges evaluated were 42-48 % for guideline adherence on the ward and 61-64 % for over-treatment on the ICU. Results were robust over sensitivity analyses concerning cost and utility estimates.

CONCLUSIONS: While adherence to antibiotic guidelines was the most cost-effective strategy for elderly patients hospitalized with CAP and admitted to the ward, in the ICU over-treatment of patients relative to the guidelines was the most cost-effective strategy.