Reliability and validity of the SF-36 Health Survey Questionnaire in patients with brain tumors: a cross-sectional study
BACKGROUND
Deterioration of health related quality of life (HRQoL) is common in brain tumor patients. This study evaluated validity and reliability of the Medical Outcomes Study 36-Item Short Form (SF-36) in patients with brain tumors.


METHODS
Two hundred and seventy-seven patients admitted for brain tumor surgery were evaluated for HRQoL (SF-36 questionnaire); depressive symptoms (Beck Depression Inventory-II or BDI-II); and functional status (Barthel index or BI). Final histological diagnosis was obtained from pathology reports.


RESULTS
Two-hundred and twenty-seven (completion rate of 82%) patients (69% women; mean age 55.8 ± 14.4 years) completed the SF-36 questionnaire. The most common brain tumor diagnosis was meningioma (40%), followed high-grade glioma (19%). Missing data rates were ≤4%. Internal consistency was adequate for all (Cronbach α ≥ .728) but Social Functioning (Cronbach α = .527) and General Health (Cronbach α = .693) subscales. Ceiling (≥36%) and floor (≥22%) effect rates were the greatest for the Role Limitations subscales. The SF-36 subscales pertaining physical health correlated the strongest with the BI score, while the SF-36 subscales pertaining emotional health correlated the strongest with the BDI-II score. Patients with mild-moderate depressive symptoms (BDI-II score ≥20) scored lower across all SF-36 subscales, and handicap patients (BI score <90) scored the lower across all, but Mental Health, subscales.


CONCLUSIONS
The SF-36 is a valid and reliable instrument in brain tumor patients and therefore can be reliably applied for evaluation of HRQoL in neuro-oncology setting. Further studies exploring other psychometric properties of the SF-36 in brain tumor patients across disease progression stages are warranted.