Quality of life measurement after stroke: uses and abuses of the SF-36.
OBJECTIVE
The Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) is widely used to measure health status after stroke. However, a fundamental assumption for its valid use after stroke has not been comprehensively tested: is it legitimate to generate scores for 8 scales and 2 summary measures using the standard algorithms? We tested this assumption.


METHODS
SF-36 data from 177 people after stroke were examined (71% male; mean age, 62). We tested 6 scaling criteria to determine the legitimacy of generating the 8 SF-36 scale scores using Likert's method of summed ratings, and we tested 2 scaling criteria to determine the appropriateness of the standard SF-36 algorithms for weighting and combining scale scores to generate 2 summary measures (physical and mental).


RESULTS
Scaling assumptions were fully satisfied for 6 of the 8 scales, but 3 of these 6 scales had notable floor and/or ceiling effects. Assumptions for generating 2 SF-36 summary measures were not satisfied.


CONCLUSIONS
In this sample, 5 of the 8 SF-36 scales had limited validity as outcome measures after stroke, and the reporting of physical and mental summary scores was not supported. Results raise questions about the use of the SF-36 in stroke, and the SF-12 that is developed from it, and highlight the importance of testing scaling assumptions when applying existing scales to new populations.
Hobart
Jeremy C
JC
Neurological Outcome Measures Unit, Institute of Neurology, Queen Square, London, United Kingdom. jeremy.hobart@phnt.swest.nhs.uk
Williams
Linda S
LS
Moran
Kimberly
K
Thompson
Alan J
AJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006766:Hospitals, County / Q000706:statistics & numerical data; D006785:Hospitals, University / Q000706:statistics & numerical data; D006786:Hospitals, Urban / Q000706:statistics & numerical data; D006787:Hospitals, Veterans / Q000706:statistics & numerical data; D006801:Humans; D007196:Indiana; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D000071939:Stroke Rehabilitation; D011795:Surveys and Questionnaires / Q000592:standards*