F Marra1, C A Marra, D M Patrick. 1. Department of Pharmacy, Vancouver Hospital and Health Sciences Centre; Faculty of Pharmaceutical Sciences and Division of Infectious Diseases, Faculty of Medicine, University of British Columbia; Pharmaceutical Outcomes Research Program, British Columbia's Children's and Women's Hospitals, Vancouver, British Columbia.
Abstract
OBJECTIVE: To assess the cost effectiveness of azithromycin versus doxycycline therapy for cervical Chlamydia trachomatis infections in Canada. DESIGN: A predictive decision analytic model using previously published clinical and economic evaluations, expert opinion and costs of medical care in Canada. POPULATION: A hypothetical cohort of 5000 women followed over 10 years. INTERVENTIONS: Two diagnostic strategies were compared, laboratory confirmed diagnosis (LCD) and presumptive diagnosis (PD) of C trachomatis infection. Under each strategy, two treatment alternatives were analyzed, a single 1 g dose of azithromycin and a seven-day course of doxycycline as 100 mg twice daily. RESULTS: Despite a fourfold higher acquisition cost, under base case conditions, for both diagnostic strategies, the azithromycin treatment alternative was more cost effective than the doxycycline alternative. For the LCD model, the cost per cure for patients receiving azithromycin was $184.76 compared with $240.59 for patients receiving doxycycline, resulting in an incremental cost of $55.83. For the PD model, the cost per cure for patients treated with azithromycin was $51.48 compared with $51.82, resulting in an incremental cost of $0.34. For the hypothetical cohort of 5000 women, the use of azithromycin translates into a projected annual cost savings of $279,150 and $1,700 for the LCD and PD models, respectively. In one-way sensitivity analyses for the LCD model, no clinically plausible changes in the base case estimates changed the results of the cost effectiveness outcome. In the PD model, clinically plausible changes in the probabilities of doxycycline cure, pelvic inflammatory disease, sequelae and chlamydia infection were found to alter the cost effectiveness outcome. CONCLUSIONS: Based on the results from our model, the azithromycin strategy should be employed for the treatment of laboratory confirmed cases. However, for presumptive cases, azithromycin should be used only if the probabilities of C trachomatis and pelvic inflammatory disease are more than 19%, doxycycline effectiveness is less than 78%, or the cost of azithromycin is less than $19.00.
OBJECTIVE: To assess the cost effectiveness of azithromycin versus doxycycline therapy for cervical Chlamydia trachomatis infections in Canada. DESIGN: A predictive decision analytic model using previously published clinical and economic evaluations, expert opinion and costs of medical care in Canada. POPULATION: A hypothetical cohort of 5000 women followed over 10 years. INTERVENTIONS: Two diagnostic strategies were compared, laboratory confirmed diagnosis (LCD) and presumptive diagnosis (PD) of C trachomatis infection. Under each strategy, two treatment alternatives were analyzed, a single 1 g dose of azithromycin and a seven-day course of doxycycline as 100 mg twice daily. RESULTS: Despite a fourfold higher acquisition cost, under base case conditions, for both diagnostic strategies, the azithromycin treatment alternative was more cost effective than the doxycycline alternative. For the LCD model, the cost per cure for patients receiving azithromycin was $184.76 compared with $240.59 for patients receiving doxycycline, resulting in an incremental cost of $55.83. For the PD model, the cost per cure for patients treated with azithromycin was $51.48 compared with $51.82, resulting in an incremental cost of $0.34. For the hypothetical cohort of 5000 women, the use of azithromycin translates into a projected annual cost savings of $279,150 and $1,700 for the LCD and PD models, respectively. In one-way sensitivity analyses for the LCD model, no clinically plausible changes in the base case estimates changed the results of the cost effectiveness outcome. In the PD model, clinically plausible changes in the probabilities of doxycycline cure, pelvic inflammatory disease, sequelae and chlamydia infection were found to alter the cost effectiveness outcome. CONCLUSIONS: Based on the results from our model, the azithromycin strategy should be employed for the treatment of laboratory confirmed cases. However, for presumptive cases, azithromycin should be used only if the probabilities of C trachomatis and pelvic inflammatory disease are more than 19%, doxycycline effectiveness is less than 78%, or the cost of azithromycin is less than $19.00.
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