Abstract
BACKGROUND: Epidemiological studies indicate that the unique high-altitude environment may promote the prevalence of hypertension. Nevertheless, whether chronic plateau exposure affects antihypertensive efficacy in hypertensive highlanders remains unknown. METHODS: This is a post hoc analysis of the OMAN Trial, a randomized controlled study that compared the antihypertensive efficacy of morning versus bedtime administration of olmesartan/amlodipine. Hypertensive patients from the OMAN Trial were stratified into highlanders (Sichuan-Tibet Plateau, altitude ≈ 3000 m) and lowlanders (Sichuan-Chengdu Plain, altitude ≈ 500 m) based on 1 : 1 propensity score matching. After 4-week treatment of olmesartan/amlodipine (20/5 mg once daily), between-group differences in office/ambulatory blood pressure (BP) reduction, control rates, and rhythms were analyzed. RESULTS: Each group comprised 171 hypertensive patients with balanced baselines. While office BP reductions were comparable between groups, highlanders showed significantly smaller reductions in 24-h ambulatory BP compared with lowlanders (between-group difference in 24-h SBP reduction: -2.39 mmHg, P = 0.048; between-group difference in 24-h DBP reduction: -1.60 mmHg, P = 0.025). More pronounced between-group differences in BP reduction were observed during the morning (ΔSBP: -7.18 mmHg, P < 0.001; ΔDBP: -4.01 mmHg, P = 0.002) and daytime (ΔSBP: -3.81 mmHg, P = 0.005; ΔDBP: -2.29 mmHg, P = 0.005) periods. Similarly, both office BP control (lowlanders: 77.2% vs. highlanders: 60.2%, P = 0.001) and 24-h BP control rates (lowlanders: 50.9% vs. highlanders: 34.5%, P = 0.002) were significantly lower in highlanders. Intriguingly, nocturnal BP reduction and control rates showed no significant intergroup differences. CONCLUSION: Our findings suggest chronic plateau exposure may attenuate antihypertensive efficacy, potentially necessitating intensified treatment regimens for BP control in highlanders. REGISTRATION: URL: https://www.chictr.org.cn/ ; Registration number: ChiCTR2200059719.