Doxycycline or Ofloxacin for Outpatient Chlamydial Pelvic Inflammatory Disease? A Cost-Benefit and Cost-Effectiveness Analysis

OBJECTIVE The current Centers for Disease Control and Prevention (CDC) guidelines include 2 drugs, doxycycline and ofloxacin, for treatment of the chlamydial component of outpatient pelvic inflammatory disease (PID). Although ofloxacin costs about $90 more than doxycycline, doxycycline is frequently associated with side effects and patient compliance with this drug is probably poor. Because clinicians have little information by which to judge the tradeoffs between price and compliance for these 2 antibiotics, we examined the impact of patient compliance in the evaluation of the costs and benefits of using each drug. METHODS The incidence and direct costs of PID sequelae (infertility, ectopic pregnancy, and chronic pelvic pain) resulting after partially treated chlamydial PID were taken from previous estimates. For differing levels of antibiotic compliance, the probability of cure, probability of the occurrence of sequelae, and the associated cost of each were calculated. Because the relationship between partial antibiotic compliance and PID cure is unknown, we included 3 plausible relationships in our analyses. The sensitivity analysis was performed by varying key assumptions and examining the effect of each on future costs. RESULTS The average probability of future PID sequelae attributable to chlamydia is slightly less than 2%, with an associated cost of $1,272. With an average compliance for doxycycline of 50%, an improvement in compliance of as little as 1.8-3.5 percentage points (51.8-53.5%), depending on the assumption used regarding partial compliance and cure, would make the use of ofloxacin less costly than doxycycline in the long run. Even with a cost difference of $90 between the 2 drugs, a 10-percentage-point increase in compliance (to 60% compliance) with the more expensive drug would save $2.63 for each $1.00 spent. CONCLUSIONS Since the long-term costs of PID are likely to overshadow the immediate cost of providing treatment, physicians should carefully consider the likelihood of patient compliance in selecting an antibiotic.