Is the SF-36 suitable for assessing health status of older stroke patients?

Introduction: the Medical Outcomes Study short form 36 health survey (SF-36) is being increasingly used and recommended as a suitable measure of subjective health status. However it is unlikely that any measure will be appropriate for all groups. We wished to determine the suitability of the SF-36 for assessing quality of life in older stroke patients. Methods: a screening questionnaire was used to identify prevalent cases of stroke from a random sample of 2000 subjects aged 45 years and over. The SF-36 was included as part of a self-completion questionnaire posted to each stroke patient. Data quality indicators were analysed. Results: we identified 104 cases of stroke and the response rate for the SF-36 questionnaires sent was 83%. Completion rates for individual items ranged from 66 to 96%. All items in the role physical and role emotional scales had completion rates < 75%. The percentage of subjects for whom an individual scale score could be computed ranged from 67 to 96%, being lowest for the role physical and role emotional scales. Floor effects were high (> 15%) for these two scales and for the social functioning and physical functioning scales. Ceiling effects were substantial (> 15%) for the two role effect scales and for social functioning and bodily pain. Conclusions: this study has shown high response rates from older stroke patients to a postal questionnaire incorporating the SF-36. The poor completion rates and consequent inability to compute scores for a large proportion of responders in certain scales raises concerns about the perceived relevance of these sections. Results for the response effects suggest that, on its own, the instrument is not suitable for assessing outcome. When data quality indicators were examined, it appears that postal administration of the SF-36 is not appropriate for assessing quality of life of older stroke patients.