COVID-19 is an emerging, rapidly evolving situation.
Get the latest public health information from CDC:

Get the latest research information from NIH: Menu

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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00843583
Recruitment Status : Completed
First Posted : February 13, 2009
Last Update Posted : May 3, 2017
Information provided by:
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

Condition or disease
Obstructive Sleep Apnea Resistant Hypertension

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.

Layout table for study information
Study Type : Observational
Estimated Enrollment : 96 participants
Observational Model: Case-Only
Time Perspective: Cross-Sectional
Official Title: A Cross-sectional Study of the Occurrence and Effect of Obstructive Sleep Apnea in Subjects With Resistant Hypertension
Study Start Date : February 2009
Actual Primary Completion Date : December 2012
Actual Study Completion Date : December 2012

resistant hypertension subjects
subjects with resistant hypertension

Primary Outcome Measures :
  1. ambulatory blood pressure [ Time Frame: 24 hour ]

Biospecimen Retention:   Samples Without DNA
Blood test for glucose, lipid, vascular and metabolic markers

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Consecutive sampling of subjects who attend Hypertension clinic , Department of Medicine, Queen Mary Hospital, and who fulfill the inclusion criteria.

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00843583

Layout table for location information
Hong Kong
Department of Medicine, The University of Hong Kong, Queen Mary Hospital
Hong Kong, Hong Kong, 852
Sponsors and Collaborators
The University of Hong Kong
Layout table for investigator information
Principal Investigator: Sau Man Mary Ip, MD Department of Medicine, The University of Hong Kong

Publications automatically indexed to this study by Identifier (NCT Number):
Layout table for additonal information
Responsible Party: Professor Ip, Sau Man Mary, Department of Medicine, The University of Hong Kong, Queen Mary Hospital Identifier: NCT00843583    
First Posted: February 13, 2009    Key Record Dates
Last Update Posted: May 3, 2017
Last Verified: May 2017
Keywords provided by The University of Hong Kong:
obstructive sleep apnea
resistant hypertension
Additional relevant MeSH terms:
Layout table for MeSH terms
Sleep Apnea Syndromes
Sleep Apnea, Obstructive
Vascular Diseases
Cardiovascular Diseases
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases