A Web-Based Sexual Health Intervention to Prevent Sexually Transmitted Infections in Hong Kong: Model-Based Cost-Effectiveness Analysis

BACKGROUND: Sexually transmitted infections (STIs) remain a significant public health concern, particularly among young adults, and Chlamydia trachomatis (CT) infections are the most common STIs in young women. One of the most effective ways to prevent STIs is the consistent use of condoms during sexual intercourse. There has been no economic evaluation of the interactive web-based sexual health program, Smart Girlfriend, within the Chinese population. OBJECTIVE: This study aimed to evaluate the long-term cost-effectiveness of Smart Girlfriend in preventing STIs in the Chinese population. The evaluation compared the program with a control intervention that used a 1-page information sheet on condom use. METHODS: A decision-analytic model that included a decision tree followed by a Markov structure of CT infections was developed since CT is the most prevalent STI among young women. The model represents the long-term experience of individuals who received either the intervention or the control. One-way and probabilistic sensitivity analyses were conducted. The main outcomes were the number of CT infections and the incremental cost as per quality-adjusted life year (QALY). RESULTS: A cohort of 10,000 sexually active nonpregnant young women initially entered the model in a noninfectious state (ie, "well"). In the base-case analysis, the implementation of the Smart Girlfriend program resulted in the prevention of 0.45% of CT infections, 0.3% of pelvic inflammatory disease, and 0.04% of chronic pelvic pain, leading to a gain of 70 discounted QALYs and cost savings over a 4-year time horizon, compared to the control group. With more than 4548 users, the intervention would be cost-effective, and with more than 8315 users, the intervention would be cost saving. A 99% probability of being cost-effective was detected with a willingness to pay US $17,409 per QALY. CONCLUSIONS: Smart Girlfriend is a cost-effective and possibly cost-saving program over a 4-year time horizon. This result was particularly sensitive to the number of website users; launching the website would be cost-effective if more than 4548 people used it. Further work is warranted to explore if the findings could be expanded to apply to women who have sex with women and in the context of other STIs. TRIAL REGISTRATION: ClinicalTrial.gov NCT03695679; https://clinicaltrials.gov/study/NCT03695679.