Short Form 36 (SF-36) Health Survey questionnaire: which normative data should be used? Comparisons between the norms provided by the omnibus survey in Britain, the Health Survey for England and the Oxford Healthy Life Survey

Background Population norms for the attributes included in measurement scal es are required to provide a standard with which scores from other study po pulations can be compared. This study aimed to obtain population norms for the Short Form 36 (SF-36) Health Survey Questionnaire, derived from a rando m sample of the population in Britain who were interviewed at home, and to make comparisons with other commonly used norms. Methods The method was a face-to-face interview survey of a random sample o f 2056 adults living at home in Britain (response rate 78 per cent). Compar isons of the SF-36 scores derived from this sample were made with the Healt h Survey for England and the Oxford Healthy Life Survey. Results Controlling for age and sex, many of mean scores on the SF-36 dimen sions differed between the three datasets. The British interview sample had better total means for Physical Functioning, Social Functioning, Mental He alth, Energy/Vitality, and General Health Perceptions. The Health (intervie w) Survey for England had the lowest (worst) total mean scores for Physical Functioning, Social Functioning, Role Limitations (physical) Bodily Pain, and Health Perceptions. The postal sample in central England had the lowest (worst) total mean scores for Role Limitations (emotional), Mental Health and Energy/Vitality. Conclusion Responses obtained from interview methods may suffer more from s ocial desirability bias (resulting in inflated SF-36 scores) than postal su rveys. Differences in SF-36 means between surveys are also likely to reflec t question order and contextual effects of the questionnaires. This indicat es the importance of providing mode-specific population norms for the vario us methods of questionnaire administration.