A Cross-sectional Study of the Occurrence and Effect of Obstructive Sleep Apnea in Subjects With Resistant Hypertension

Completed

• Conditions: Resistant Hypertension; Obstructive Sleep Apnea

• Registration Number: NCT00843583
• Lead Sponsor: The University of Hong Kong

Brief Summary

This study aims to investigate the prevalence of obstructive sleep apnea (OSA) in subjects with resistant hypertension and to evaluate the relationship between parameters of OSA severity and blood pressure control

Detailed Description

Obstructive sleep apnea (OSA) is characterized by intermittent upper airway collapse during sleep, which results in hypoxia, arousals and surge in sympathetic activity. There is robust evidence to support a contributing role of OSA in hypertension (HT). The Sleep Heart Health Study (1), which recruited more than 6000 subjects having polysomnogram at home, found an independent association between OSA and HT. The adjusted odds ratio was 1.37 for subjects with and apnea-hypopnea index \>= 30/hour compared to those without apnea. The Wisconsin Sleep Cohort Study , which provided prospective longitudinal follow-up for OSA subjects over 4 years, have shown dose dependency of the severity of OSA and the risk of development of HT. Current available data suggests that in hypertensive patients with severe OSA, there is a BP drop of about 10mmHg with CPAP treatment (2-5). The blood pressure (BP) lowering effect of CPAP treatment in the group with mild asymptomatic OSA is less consolidated.

The relationship between BP and risk of cardiovascular events is continuous, consistent, and independent of other risk factors. A strict blood pressure control is imperative in subjects with diabetes mellitus or renal impairment. Resistant hypertension is defined as blood pressure that remains above goal in spite of concurrent use of 3 antihypertensive agents of different classes. (6) Resistant hypertension is defined in order to identify patients who are at risk of having secondary causes of hypertension, and who may benefit from specific diagnostic and therapeutic applications. Despite the fact that OSA is listed as one of the causes of resistant HT (6), paucity of works has demonstrated the scale of problems of untreated OSA in subjects with resistant HT. (7-9) There is so far one study demonstrating the beneficial effect of CPAP treatment in subjects with resistant HT, though no randomization was implemented and the sample size was limited (n=11). (10) We aim at conducting a cross-sectional study to explore the situation which would guide further clinical trial.

Study Timeline

• Study Start: 2009-02
• Study First Submitted: 2009-02-12
• Study First Submitted QC: 2009-02-12
• Study First Posted: 2009-02-13
• Primary Completion: 2012-12
• Study Completion: 2012-12
• Status Verified: 2017-05
• Last Update Submitted: 2017-05-02
• Last Update Posted: 2017-05-03

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 96

Inclusion Criteria

• ≧ 3 anti-HT drugs
• age 18-65
• mentally fit for signing an informed written consent

Exclusion Criteria

• moderate renal impairment (glomerular filtration rate <30 mL/min/m2 )
• endocrine/renal/cardiac causes of secondary HT
• congestive heart failure and clinically fluid overloaded
• On drugs that elevate BP e.g. alcohol, NSAID, steroid

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
ambulatory blood pressure	24 hour

Trial Locations

Locations (1)

Department of Medicine, The University of Hong Kong, Queen Mary Hospital; 🇭🇰 Hong Kong, Hong Kong