A decision analysis to guide antibiotic selection for Chlamydia infection during pregnancy

To analyze the cost and effectiveness of different antibiotic combinations for the treatment of infection with Chlamydia trachomatis in pregnant women.

Using availability treatment effectiveness rates from the literature, a decision analysis model was constructed to determine the effectiveness and cost of therapy with 4 antibiotics shown to be useful for Chlamydia infection during pregnancy. Women who were still infected after initial therapy were then treated with a second antibiotic. Outcomes included the total cost of the treatment (including pretreatment and posttreatment cultures and antibiotic cost) and treatment failure rates.

The lowest failure rates could be achieved with the use of amoxicillin followed by azithromycin for treatment failures or azithromycin followed by clindamycin hydrochloride. When costs were compared, a strategy starting with amoxicillin followed by azithromycin for nonresponders was favored, with costs approximately 15% lower than starting with azithromycin followed by amoxicillin. Strategies using clindamycin were significantly more expensive. The drug combination recommended by the Centers for Disease Control and Prevention (erythromycin followed by amoxicillin in nonresponders) was more expensive than amoxicillin-azithromycin and had one of the highest failure rates. Variation in the cost of the medications and in the effectiveness of the antibiotics under consideration did not significantly alter the findings.

For pregnant women infected with Chlamydia, initiating treatment with amoxicillin, 500 mg 3 times a day for 7 days, followed by a single 1-g dose of azithromycin for nonresponders is the most cost-effective strategy for treatment.