BACKGROUND: Self-efficacy in mpox (formerly known as monkeypox) prevention plays a pivotal role in promoting preventive behaviors by fostering a sense of control and motivation, especially among men who have sex with men (MSM), the population most affected by mpox in many countries. OBJECTIVE: This study aims to assess the mpox prevention self-efficacy among MSM in China and identify factors influencing it, using a validated mpox prevention self-efficacy scale. METHODS: From October 2023 to March 2024, a nationwide cross-sectional study was conducted among MSM (aged ≥18 years) across 6 geographic regions in China using a snowball sampling method. The recruited participants (effective response rate=2403/2481, 96.9%) were asked to complete an anonymous questionnaire designed based on prior knowledge of mpox and social cognitive theory. The mpox prevention self-efficacy scale was evaluated for construct validity using exploratory factor analysis and confirmatory factor analysis, and its reliability was assessed using the Cronbach α coefficient. Univariate and multivariable logistic regression analyses were used to examine the factors associated with mpox prevention self-efficacy among MSM. RESULTS: A total of 2403 MSM participants were included, with a mean age of 29 (IQR 19-39) years. Of these, 1228 (51.1%) were aged 25-34 years, 1888 (78.6%) held a college degree or higher, and 2035 (84.7%) were unmarried. The median mpox prevention self-efficacy score was 23 (IQR 18-28). Exploratory factor analysis retained 6 items of the mpox prevention self-efficacy scale. Confirmatory factor analysis confirmed a strong model fit (χ²₅=32.1, n=1225
P<
.002
comparative fit index=0.991
root mean square error of approximation=0.067
standardized root mean square residual=0.02
goodness-of-fit index=0.992
normed fit index=0.990
incremental fit index=0.991
Tucker-Lewis index=0.974), with all indices within acceptable ranges. The scale demonstrated good internal consistency, with a Cronbach α of 0.859. The positive factors associated with mpox prevention self-efficacy were mpox-related knowledge (OR 1.107, 95% CI 1.070-1.146), perceived risk awareness (OR 1.338, 95% CI 1.132-1.583), and mpox risk perception (OR 1.154, 95% CI 1.066-1.250), while the negative factor was age, with individuals aged 25 years and older exhibiting lower self-efficacy in mpox prevention (25-34 years: OR 0.789, 95% CI 0.642-0.970
35-44 years: OR 0.572, 95% CI 0.444-0.736
45 years and older: OR 0.569, 95% CI 0.394-0.823). CONCLUSIONS: These findings highlight the critical role of targeted interventions to enhance mpox prevention self-efficacy, particularly through increasing knowledge, perceived risk awareness, and risk perception. Such interventions are especially important for middle-aged and older MSM, who may experience a decline in self-efficacy. Strengthening self-efficacy in these areas is essential for promoting sustained preventive behaviors, improving mental well-being, and contributing to more effective mpox prevention and control within the MSM community.