Background: The Kailuan Study examined cardiovascular risk factors in a Chinese cohort comprising employees of the Kailuan Coal Group who underwent regular health examinations.
Patients and methods: Normotensive participants in the Kailuan study were enrolled in the present work and followed up for a median of 5.8 years to assess the development of hypertension (systolic blood pressure [SBP] ≥140 mmHg, diastolic blood pressure [DBP] ≥90 mmHg, or initiation of blood pressure [BP] medications).
Results: This study comprised a total of 50,024 participants (age, 47.9 ± 12.0 years; male/female, 37,429/12,595), of whom 22,176 (44.3%) developed hypertension. In both male and female subjects, there was an increase in multivariable-adjusted hazard ratios for hypertension in all waist circumference (WC) groups (group 1, <70 cm; group 2, 70-79 cm; group 3, 80-89 cm; group 4, 90-99 cm; group 5, ≥100 cm). Results of a stratified analysis of subjects with normal body mass index (BMI; <24 kg/m2) showed that hazard ratios for hypertension still increased across WC groups. Significant interactions were found between WC groups and gender (p <0.001), as well as between WC groups and BP categories (p <0.001). Increased WC was associated with a significantly higher risk of hypertension incidence in men compared with women and in subjects with a high-normal BP vs. those with an ideal BP.
Conclusion: WC is an independent predictor of hypertension incidence. The association between WC and hypertension incidence is affected by gender and baseline BP levels.
Keywords: Body mass index; Gender; Hypertension; Obesity; Waist circumference.