Authors (including presenting author) :
Tse TK, Chiang LK
Affiliation :
Family Medicine and General Outpatient Department, Kwong Wah Hospital
Introduction :
Hypertension is one of the commonest chronic diseases managed in primary care. Absence of nocturnal dipping of blood pressure was identified in 35 to 65% of hypertensive patients by 24-hour ambulatory blood pressure monitoring. This phenomenon was postulated to be associated with several factors, including diabetes mellitus, chronic renal disease and obstructive sleep apnoea (OSA). Screening of diabetes mellitus and chronic renal disease were included in routine complication screening of hypertension. However, current guidelines on the management of hypertension did not address on the need on screening for OSA in non-dipping patients. This may delay the diagnosis of OSA, which is a treatable illness and a well-known reversible risk factor for cardiovascular disease.
Objectives :
1) To estimate the prevalence of overnight pulse oximetry screened OSA among nocturnal dipping and non-dipping hypertensive patients.
2) To assess the relationship between overnight pulse oximetry screened OSA and the nocturnal dipping blood pressure pattern.
Methodology :
Study Design: Cross-sectional study.
Subjects and Procedure: Subjects were recruited by consecutive sampling. 61 dippers and 61 non-dippers in the general out-patient clinic of Kwong Wah Hospital were invited to perform an overnight pulse oximetry. Main Outcome Measures: The prevalence of overnight pulse oximetry screened OSA among nocturnal dipping and non-dipping hypertensive patients.
Result & Outcome :
The mean age of the subjects was 61.57 ± 11.43 years. 80 of them (65.5%) were female. 97 of our subjects (76.9%) were overweight or obese.
27 out of 61 dippers (44.3%) and 37 out of 61 non-dippers (60.7%) were screened positive for OSA respectively.
Our study showed that OSA is highly prevalent among hypertensive patients. Moreover, non-dippers tended to be more likely to have OSA, despite it is not statistically significant (P=0.070). Further studies on the association between non-dipping and OSA are recommended.
Our study results also suggested that clinicians should be aware of the high prevalence of OSA among hypertensive patients, especially the non-dipping group. Careful screening of excessive daytime sleepiness and other associated symptoms of OSA by using Epworth Sleepiness Scale (ESS) and overnight pulse oximetry in the high risk group should be promoted.
ESS is a validated, self-administered questionnaire, which can be used by both doctors and allied health professionals. Overnight pulse oximetry is also readily available in some general out-patient clinics. These assessments may be incorporated into our complication screening of hypertensive patients in future, in order to provide a more comprehensive care.
Co-location with:
