The knowledge paradox: an inverted U-shaped association between HIV knowledge and stigma among older men in Sichuan Province, Southwest China.

Background: Older men (≥50 years) in China face elevated HIV infection risks, yet HIV stigma remains a significant barrier to prevention. Although HIV knowledge is frequently assumed to reduce stigma, the evidence is inconsistent. This cross-sectional study examined the association between HIV knowledge and stigma among older men in Southwest China, specifically investigating potential nonlinear patterns within sociocultural contexts. Methods: We conducted a cross-sectional survey from July to August 2023 in three high-HIV-burden areas of Sichuan Province. Using a multi-stage cluster random sampling design, 841 HIV-negative men completed structured interviews. All analyses incorporated survey weights to ensure representativeness. HIV knowledge was assessed via a validated 8-item scale (score range 0-8). Stigma was measured with an adapted 10-item scale (score range 10-50). Survey-weighted hierarchical linear regression was used to test linear and quadratic associations adjusted for covariates. Survey-weighted segmented regression analyses confirmed robustness. Results: The weighted mean HIV knowledge score was 4.39 (SD = 2.13), and the weighted mean stigma score was 31.78 (SD = 5.60). Regression analysis revealed an inverted U-shaped association. Stigma initially increased with increasing knowledge (linear Conclusion: Among older Chinese men, HIV knowledge has an inverted U-shaped association with stigma. Initial knowledge acquisition correlates with heightened stigma, potentially reflecting sociocultural interpretations of fragmented information. Only beyond a specific threshold does further knowledge correlate with reduced stigma. Interventions may need to be staged or tailored based on individuals' existing knowledge levels, addressing both the nonlinear knowledge-stigma dynamic and underlying sociocultural norms.