Chronic plateau exposure attenuates antihypertensive efficacy in highlanders: insights from the OMAN trial

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.

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.

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.

Our findings suggest chronic plateau exposure may attenuate antihypertensive efficacy, potentially necessitating intensified treatment regimens for BP control in highlanders.

URL: https://www.chictr.org.cn/ ; Registration number: ChiCTR2200059719.