The SF-36 developed by Ware et al. (1993) evaluates general health status, and was intended to fill a gap between the much more lengthy questionnaires and other relatively coarse single-item measures (Appendix E3). It is designed to provide assessments involving generic health concepts that are not specific to any age, disease or treatment group. Emphasis is placed upon physical, social and emotional functioning. The SF-36 has become the most widely used of the general health status measures. It can be either self-assessed or administered by a trained interviewer.
As the name implies, there are 36 questions addressing eight health concepts (a simpler 12-question form, the SF-12, is also available). There are two summary measures, physical health and mental health. Physical health is divided into scales for physical functioning (10 items), role-physical (4), bodily pain (2) and general health (5). Mental health comprises scales for vitality (4 items), social functioning (2), role-emotional (3) and mental health (5). In addition, there is a general health transition question, which asks: "Compared to one year ago, how would you rate your general health now?" There is also a global question about the respondent's perception of their health: "In general, would you say your health is: (excellent, very good, good, fair, poor)?" Most questions refer to the past four weeks, although some relate to the present. A few questions, such as those for "role-physical", take yes/no responses, while some, such as the physical functioning items, have three categories (limited a lot, limited a little, not limited at all), and other items have five or six categories for responses.
The designers of the SF-36 selected, standardised and tested the items so that they can be scored using the standard scoring method.
Most of the items appear broadly sensible. However, the physical functioning scale, in common with many similar scales, poses questions about interpretation. Questions ask whether your health limits you in "vigorous activities, such as running, lifting heavy objects, participating in strenuous sports" or in "walking more than a mile". It is not clear how those who never participate in such activities should respond—their health may be severely impaired, and yet they should respond "No, not limited at all" and will therefore receive a score indicating better functioning than might be expected. Some of the alternative questionnaires therefore restrict physical functioning questions to activities that are expected to be applicable to everyone, whilst others such as the Rotterdam Symptom Checklist (described below) stress that the questions are hypothetical.
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