A preliminary exploration of the construct validity of the Berlin questionnaire as a measure of obstructive sleep apnoea in a South African population : a clinical health psychology perspective.
Clinical professionals in South Africa are generally unaware of the impact of obstructive sleep apnoea (OS A). The cost to the state of untreated apnoea may be extremely high. In primary health care encounters OSA often goes undiagnosed. The cascade of symptoms linked to OSA is profound, placing patients at risk for debilitating problems impacting on self and others. The aim of this study was to validate a questionnaire, which could be used at a primary health care level to identify patients with OSA thus cutting costs and improving efficient, effective and ethical service to patients. The Berlin Questionnaire (BQ) (Netzer et al. 1999) was administered to a clinical sample of consenting patients at a private sleep laboratory in Durban, South Africa (N = 119)(completed n = 110). Home-based sleep studies (n = 116) on a portable cardio-respiratory screening device were also obtained for objective comparison. From the results obtained in this South African sample, the BQ showed low validity and reliability (Cronbach a = 0.62 - 0.84) to individual items of the BQ. The total BQ score and high-risk symptom category analysis showed mildly significant correlations with internationally approved protocols. The BQ identified 60% of the high-risk group (AHI >5). Furthermore, risk categories were useful in predicting AHI ratings in 64% of moderate OSA cases and 25% of severe OSA cases. The BQ therefore has useful psychometric properties as an adjunct assessment tool to screen for high-risk OSA cases where resources are scant. Clinical health psychologists are in an ideal position to recognise the risk factors and symptoms of OSA. The clinical assessment and the value of the correct diagnosis will alleviate the treatment of psychological symptoms at a superficial level in primary health care facilities.