Validity and Reliability of the Short Form Health Survey Questionnaire (SF-36) for Use in Iranian Patients With Traumatic Brain Injury (TBI)

The assessment of Quality of Life (QoL) as a measurement of Traumatic Brain Injury (TBI) outcome can play a key role in identifying the adverse effects of TBI. There is no study on the evaluation of psychometric properties of the Persian version of Short Form Health
Survey Questionnaire (SF-36) in the TBI patient population. Therefore, the present study aimed to validate and test the reliability of the Persian version of the SF-36 in patients with TBI.

In the present cross-sectional study, 185 patients with TBI were selected by non-probability and consecutive sampling. First, the construct validity of the Persian version of the SF-36 questionnaire was evaluated using the Confirmatory Factor Analysis (CFA) in AMOS-22, and then the internal consistency reliability and item-total score correlation of each subscale were assessed by SPSS V. 22.

Results of CFA indicated that the dimensionality of SF-29 questionnaire with eight-factor structure among the Iranian TBI patients had construct validity (GFI=0.825, CFI=0.963, NFI=0.919, TLI=0.957, RMSEA=0.06) by eliminating 6 items and freeing some of the covariance errors between items, but the two-factor dimensionality (physical and psychological components of QoL) of this questionnaire was not approved. Internal consistency of the eight-factor form of SF-29 subscales was acceptable to excellent (=α0.70 to 0.99). Correlation analysis of item-total score for determining the construct validity of SF-29 indicated that except for 2 items, all items of the questionnaire had a positive and strong correlation with their subscales (r=0.40 to 0.99, P<0.0001).

Persian version of SF-29 with an eight-factor construct had good validity and reliability and could be used to measure health-related QoL in Iranian patients with TBI.