Abstract
The SF-36 questionnaire is considered to be one of the most important measures in health economics of health status and quality of life. However, this questionnaire has not yet been used in khat-related studies in the Kingdom of Saudi Arabia. We aim to assess the reliability and validity of the SF-36 questionnaire on khat chewers in the Jazan region of Saudi Arabia. A total of 450 khat chewers were selected to answer this questionnaire from March 2nd to April 30th, 2012. We first report descriptive and correlation analyses of the data. Then using a construct validity analysis, we uncover the underlying structure of the SF-36 questionnaire. Finally, Cronbach's alpha and intraclass correlation coefficient analyses were performed to assess the internal consistency of the questionnaire. For the demographic variables, we found age to be negatively associated with SF-36 scales (p a parts per thousand currency signaEuro parts per thousand 0.05), whereas education was positively associated (p a parts per thousand currency signaEuro parts per thousand 0.05). Importantly, we observed that khat has a negative impact on the quality of life of its users; therefore, intervention measures are needed to solve this problem. The principal component factor analysis of the construct validity confirmed the presence of eight factors in the SF-36, with some of the subscale components remaining as independent factors. Finally, the internal consistency for this questionnaire was high (alpha 0.72-0.90) across the eight subscales. The above results suggest that the SF-36 questionnaire is a useful scale to measure the quality of life of khat consumers. This study has potential implications in shaping healthcare policy, particularly in evaluating the economic burden of khat consumption and calculating 'years of life lost' and 'years lived with disability'.