Detailed evaluation of mental and physical health related quality of life
The SF-36 questionnaire is a validated tool for generic evaluation of patients’ physical and mental health. Its 36 items cover multiple dimensions, such as physical functioning, bodily pain, general health, vitality, social functioning and mental health. Owing to the high number of items, health assessment with the SF-36 is very detailed and precise, but might take patients—especially elderly people—more time to complete than other generic measure tools will .
This questionnaire has been used in various studies in different medical disciplines, including in patients with compression fractures (orthopedics), stroke (neurology) and asthma (pulmonology).
Items - Dimensions - Completion time
The 36 items must be answered by selecting 1 of 2–6 response options.
The questionnaire covers 8 dimensions: physical functioning (10 items), role limitations due to physical health problems (4 items), bodily pain (2 items), general health (5 items), vitality (4 items), social functioning (2 items), role limitations due to personal or emotional problems (3 items) and mental health (5 items). There is 1 item on perceived change in health. 6
In a publication including elderly patients, the completion time varied from 4 to 30 minutes, the median being 8 minutes, and 84% completed the survey in 10 minutes. 7
Versions 1.0 and 2.0 are scored differently.
Version 1.0 (RAND Health Care):
Each response for each item is scored from 0 to 100, 100 being the best possible health condition and 0 the worst. The points of the responses for each dimension are averaged to calculate the dimension score (0–100). There is no total score.
Items skipped are not taken into account, and the scoring mechanism remains the same (only completed items are included in calculating the average score per dimension).
Version 2.0 (QualityMetric):
The results are represented by 1 physical component score and 1 mental component score. The physical component score includes the items on parameters of physical functioning and pain, whereas the mental component score includes the mental health items. The patient’s responses can be submitted on qualitymetric.com, where an API will score the raw data. Each answer is linked with an indicator variable and different regression weights during the score calculation, and norm-based scoring is employed. 8 9
For both versions, the higher the score, the better the patient’s health.
For version 2.0, each subscore as well as the physical component score and mental component score can be interpreted individually. A score of 50 represents the average in comparison with the U.S. reference population employed. The standard deviation is 10 (a score of 60 equals 1 standard deviation above the U.S. average).