RESUMO
The aim of the study was to assess factor structure, internal consistency and validity of the Italian version of the World Health Organization Disability Assessment Schedule 12-item version (WHODAS-12) in patients scheduled for neurosurgical procedures for brain tumours, cerebrovascular or spinal diseases. Disability was assessed with the WHODAS-12, quality of life with the eight-item European Health Interview Survey-Quality of Life, well-being with the Psychological General Well-Being Index-Short and general health with the Karnofsky Performance Status (KPS) scales. Factor analysis was used to confirm WHODAS-12 one-factor structure; root mean square error of approximation (RMSEA) and χ2/d.f. ratio were used to test the model fit. Internal consistency was assessed with Cronbach's α coefficient, item-total correlation and interitem correlation; convergent validity was assessed with Pearson's coefficient and discriminative validity was assessed with the t-test, dividing patients between those with KPS greater than 90 and KPS of 90 or less. The one-factor structure was confirmed (RMSEA=0.079; χ2/d.f.=2.16) and internal consistency was adequate. Correlations between the three outcome measures were significant, negative and moderate; the t-test showed disability scores to be statistically significantly higher in patients with KPS of 90 or less. Our results confirm factor structure and validity of WHODAS-12 in Italian neurosurgical inpatients; we therefore support its use in neurosurgery departments.