Candidate for the Lee B. Lusted Student Prize Competition
Method: We developed a cost-effectiveness model based on data from two randomized controlled trials and modeled the different cohorts in two separate analyses. Cohort one comprised all adults with ARTIs presenting in the outpatient setting. Cohort two comprised all adults with ARTIs presenting in the outpatient setting and judged by their providers to require antibiotics after clinical evaluation. Both analyses assumed a societal perspective and a clinic visit time horizon. We compared two strategies: usual care and procalcitonin-guided antibiotic therapy. The primary differences between strategies were the procalcitonin testing costs and fewer antibiotic prescriptions in the procalcitonin strategy. The primary outcome was cost per antibiotic avoided. Because there is not an accepted societal willingness-to-pay threshold for this outcome, we developed an estimate for this threshold based on the societal cost of antibiotic resistance per outpatient antibiotic prescription. For each cohort, we performed base case cost-effectiveness analyses and examined model robustness to parameter variation in sensitivity analyses.
Result: We estimated the willingness-to-pay threshold as $43 (range $0–$333) per antibiotic avoided, reflecting the estimated societal cost of antibiotic resistance per outpatient antibiotic prescription. In the cohort including all adults with ARTIs, the procalcitonin strategy cost more ($49 vs. $15 per patient) and reduced the number of antibiotic prescriptions (0.14 vs. 0.37 antibiotic prescriptions per patient) compared to usual care, resulting in an incremental cost-effectiveness ratio (ICER) of $149 per antibiotic prescription avoided. In a probabilistic sensitivity analysis, the likelihood of procalcitonin being favored over usual care was 2.8%. In the cohort including adult ARTIs judged by their providers to require antibiotics, the procalcitonin strategy cost more ($51 vs. $29 per patient) and reduced the number of antibiotic prescriptions (0.25 vs. 0.97 antibiotic prescriptions per patient) compared to usual care, resulting in an ICER of $31 per antibiotic prescription avoided. In a probabilistic sensitivity analysis, the likelihood of procalcitonin being favored over usual care was 58.4%.
Conclusion: Procalcitonin-guided antibiotic therapy for outpatient management of ARTIs in adults is cost-effective compared to usual care when the societal costs of antibiotic resistance are considered and procalcitonin testing is limited to adults with ARTIs judged by their providers to require antibiotics after clinical evaluation.