Objective To explore the distribution and impact of sitting and supine blood pressure measurements on prevalenve of hypertension, as well as to investigate the differences of this impact among different ages and genders.

Methods A study was conducted from March to July 2021 in Fuxin Mongolian Autonomous County, Fuxin City, Liaoning Province. A total of 3 660 people from 4 townships and 33 natural villages participated in the data collection. After excluding the subjects who lacked sitting and supine blood pressure measurements, a total of 2 379 individuals were included in this study. With an average age of (61.6±9.6) years. Among them, 830 were male, accounting for 34.9%. Hypertension in the sitting and supine positions were defined as systolic blood pressure≥140 mmHg and/or diastolic blood pressure≥90 mmHg, and/or having received antihypertensive medication within the past two weeks. Continuous data were analyzed using t tests, and rate comparisons were conducted using χ² tests. Multivariate logistic regression analysis was applied to explore the effects of gender and age on hypertension in the sitting and supine positions. Sensitivity analysis was performed after excluding individuals with medication-taking behavior.

Results The results showed that the systolic and diastolic blood pressures in the supine position were higher than those in the sitting position (141.7±21.3) vs (137.3±21.0) mmHg, t=−18.218, P＜0.001; (85.9±11.3) vs (85.3±11.2) mmHg, t=−4.489, P＜0.001, and the prevalence of hypertension in the supine position was higher than that in the sitting position (54.8% vs 41.5%, χ²=884.931, P＜0.001). 406 (17.1%) individuals only had hypertension in the supine position. Multivariate logistic regression analysis revealed that individuals with normal sitting blood pressure but hypertension in the supine position were more likely to be found in females (OR=1.427, 95%CI: 1.108−1.838) and the elderly(≥65 years old, OR=2.110, 95%CI: 1.675−2.659). The sensitivity analysis results indicated that females and the elderly (≥65 years old) were the high-risk groups for only having hypertension in the supine position.

Conclusions There are significant differences in blood pressure measurements and the prevalence of hypertension between the sitting position and the supine position; the blood pressure measurements and the prevalence of hypertension in the supine position are both higher than those in the sitting position. The situation of only having hypertension in the supine position is more common among women and the elderly (≥65 years old).