Abstract
BACKGROUND: Hypertension represents a significant global health concern, with central obesity widely acknowledged as a pivotal risk factor. The objective of this study was to investigate the association between waist-to-height ratio (WHTR) and hypertension risk, identify specific thresholds. METHODS: We analyzed data from 7,712 participants of the China Health and Retirement Longitudinal Study (CHARLS), aged ≥ 45 years and free of hypertension at baseline (2011–2012),with follow-up until 2020. Waist-to-height ratio (WHtR) was the primary exposure and incident hypertension the main outcome. Covariates included demographic, lifestyle, and metabolic factors. To flexibly model the association between WHtR and hypertension risk, we used restricted cubic spline regression. Threshold effect analysis was conducted using two-piecewise linear regression, with the inflection point determined via log-likelihood maximization and assessed using the likelihood ratio test. RESULTS: There was a non-linear association between WHtR and incident hypertension, with an inflection point (cut point) at WHtR = 0.443. Below this threshold, higher WHtR was not associated with increased risk of hypertension (HR = 0.79, 95% CI: 0.71–0.89). However, above the cut point, each 0.1-unit increase in WHtR was associated with an 82% increased risk of developing hypertension (HR = 1.82, 95% CI: 1.68–1.96). The risk difference before and after the cut point was statistically significant (HR = 2.28, 95% CI: 1.96–2.66). CONCLUSION: Higher WHtR is independently associated with a greater risk of hypertension in Chinese adults. The optimal cut-off identified in our cohort (0.438) is lower than commonly used Western thresholds. Population-specific cut-offs may improve screening and prevention efforts. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12872-026-05691-2.