Differential performance of SF-36 items in healthy adults with and without functional limitations.
OBJECTIVE
To determine whether Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) items show differential item functioning among healthy adults with various types of functional limitations as compared with a healthy sample with no identified limitations.


METHODS
Survey responses were analyzed by using partial correlations.


METHODS
General community.


METHODS
Participants (N=206) included (1) adults with spinal cord injury (SCI), (2) adults who were deaf or hard of hearing, (3) adults who were legally blind, (4) adults with psychiatric or emotional conditions, and (5) adults with no reported functional limitations. Participants were screened to ensure the absence of substantial health problems.


METHODS
Not applicable.


METHODS
SF-36.


RESULTS
Partial correlations showed a significant negative correlation, indicating differential item functioning (ie, apparent bias) for people with SCI on all 10 SF-36 Physical Functioning items. For people who were blind, 5 items showed a significant negative correlation. Two items had significant negative correlations for the deaf/hard-of-hearing group. One item showed significant negative performance for people with mental health conditions.


CONCLUSIONS
Our data indicated a possibility for measurement bias caused by the blending of health and function concepts in the SF-36.
Horner-Johnson
Willi
W
Oregon Institute on Disability & Development and the Department of Public Health and Preventive Medicine, Oregon Health & Science University, Portland, OR 97201-0574, USA. hornerjo@ohsu.edu
Krahn
Gloria L
GL
Suzuki
Rie
R
Peterson
Jana J
JJ
Roid
Gale
G
Hall
Trevor
T
D000328:Adult; D001766:Blindness / Q000523:psychology / Q000534:rehabilitation; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000523:psychology* / Q000534:rehabilitation*; D005260:Female; D006304:Health Status; D006306:Health Surveys; D034381:Hearing Loss / Q000523:psychology / Q000534:rehabilitation; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000523:psychology / Q000534:rehabilitation; D008875:Middle Aged; D026741:Physical Therapy Modalities; D011788:Quality of Life; D015203:Reproducibility of Results; D012959:Socioeconomic Factors; D013119:Spinal Cord Injuries / Q000523:psychology / Q000534:rehabilitation