"Shotgun" versus sequential testing. Cost-effectiveness of diagnostic strategies for vaginitis

Abstract

Background: Although vaginitis is a common outpatient problem, only 60% of patients can be diagnosed at the initial office visit of a primary care provider using the office procedures of pH testing, whiff tests, normal saline, and potassium hydroxide preps.

Objective: To determine the most cost-effective diagnostic and treatment approach for the medical management of vaginitis.

Design: Decision and cost-effectiveness analyses.

Participants: Healthy women with symptoms of vaginitis undiagnosed after an initial pelvic exam, wet mount preparations, pH, and the four criteria to diagnose bacterial vaginosis.

Setting: General office practice.

Methods: We evaluated 28 diagnostic strategies comprised of combinations of pH testing, vaginal cultures for yeast and Trichomonas vaginalis, Gram's stain for bacterial vaginosis, and DNA probes for Neisseria gonorrhoeae and Chlamydia. Data sources for the study were confined to English language literature.

Measurement: The outcome measures were symptom-days and costs.

Results: The least expensive strategy was to perform yeast culture, gonorrhoeae and Chlamydia probes at the initial visit, and Gram's stain and Trichomonas culture only when the vaginal pH exceeded 4.9 (330 dollars, 7.30 symptom days). Other strategies cost 8 dollars to 76 dollars more and increased duration of symptoms by up to 1.3 days. In probabilistic sensitivity analysis, this strategy was always the most effective strategy and was also least expensive 58% of the time.

Conclusions: For patients with vaginitis symptoms undiagnosed by pelvic examination, wet mount preparations and related office tests, a comprehensive, pH-guided testing strategy at the initial office visit is less expensive and more effective than ordering tests sequentially.

FIGURE 1

One-way sensitivity analysis. Bars show the range of incremental cost-effectiveness of adding Neisseria gonorrhoeae and Chlamydia probes to yeast culture and pH guided testing for bacterial vaginosis and Trichomonas. Baseline values for each variable are shown in parenthesis. Left-hand numbers represent the threshold at which GC/Chlamydia probes become cost-saving. Right-hand numbers represent the upper bound in sensitivity analysis.