• Vol. 35 No. 1, 6–10
  • 15 January 2006

The Clinical Predictors of Hypertension and Sleepiness in an Asian Population with Sleep-disordered Breathing



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Introduction: The objective of this study was to identify the clinical predictors for hypertension and sleepiness in an Asian population with sleep-disordered breathing (SDB).

Materials and Methods: This is a retrospective, consecutive case series of 228 patients with symptoms of SDB referred to a tertiary level sleep disorders unit. A full sleep history, body mass index (BMI), Epworth Sleepiness Score (ESS), apnoea-hypopnoea index (AHI) and lowest oxygen saturation were recorded. All patients had an in-hospital polysomnogram. AHI ≥5 defined SDB. ESS >8 defined sleepiness.

Results: A BMI of 25 had a positive and negative predictive value of 75% and 56%, respectively, for predicting AHI ≥5, area ROC (receiver operating curve) = 0.668. Patients with AHI >5 had 3 times the risk of developing hypertension compared to the population with AHI <5. Using stepwise multivariate analyses with constant, age, BMI and lowest oxygen desaturation were predictors for hypertension. Patients with AHI ≥5 were 1.88 times more likely to have ESS >8. After stepwise multivariate analyses, the subjective complaint of sleepiness and lowest oxygen saturation during sleep were predictors of ESS >8.

Conclusion: The lowest oxygen saturation attained during sleep was the common factor for hypertension and sleepiness in our Asian SDB population. Mild obesity predisposes to AHI ≥5 in our population, the threshold at which the risk of hypertension is 3-fold compared with AHI <5. The subjective complaint of sleepiness predicted an ESS of >8.

Sleep physicians have only recently began to learn much about the epidemiology of sleep-disordered breathing (SDB) from large, well conducted prospective community-based studies. These studies have helped identify the risk factors for identifying sleep apnoea, particularly in the Western population.

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