The reliability and validity of short form-36 questionnaire in patients with gout

Objective To investigate the reliability and validity of the medical outcomes by applying short form-36 (SF-36) in evaluating gout patients' health related quality of life (HRQOL). Methods Gout patientswere enrolled between March 2016 and June 2016 in Foshan Hospital of Traditional Chinese Medicine. Patients completed the SF-36 questionnaire. Summary scores, physical component summary (PCS) and mental component summary (MCS) were calculated by summing factor-weighted scores across all 8 subscales, with factor weights derived from general population. The indicators of reliability and validity included internal consistency, test-retest reliability, structural and discriminant validity, ceiling and floor effect. Results Totally 306 patients were enrolled. The internal consistency test showed that the Cronbach α coefficients ranged from 0.782 to 0.822, and the test-retest reliability coefficients ranged from 0.720 to 0.986 (P<0.01). Structural validity analysis showed that there were two items whose eigenvalues were greater than one with the cumulative contribution rate of 66.1%. The discriminant validity analysis found that patients with more numbers of tophi, higher frequency of flare, multi-arthrosis involved and more complications had less scores of PCS and MCS (P<0.05). There was a high ceiling effect on physiological function and a higher ceiling and floor effect on role limitation and emotional function caused by impaired physical health. Conclusion The SF-36 can be used for the assessment of HRQOL in Chinese gout patients but disease specific questionnaire are warranted. Key words: Gout; Quality of life; Validity analysis; Content validity