Assessment of quality of life in individuals with chronic headache. Psychometric properties of the WHOQOL-BREF

BACKGROUND: The WHOQOL-BREF is a frequently used instrument for the assessment of health-related quality of life. Unlike other generic instruments used for the assessment of this construct, little is known about its properties in individuals with headache disorders. The present study examines the reliability and factorial validity of the WHOQOL-BREF in individuals with chronic headache residing in Austria. METHODS: Data from a representative population-based survey on 963 individuals with chronic headache surveyed between 2013 and 2015 was used. The factorial validity was examined by means of confirmatory factor analysis. Differential item functioning related to sex was analyzed using multiple indicators multiple causes models. RESULTS: Information on 239 men and 724 women with chronic headache was available. The four-factor, 24-item baseline model showed a moderate fit (RMSEA = 0.066; CFI = 0.868; TLI = 0.852; SRMR = 0.053), which improved significantly after the addition of six error covariances (RMSEA = 0.052; CFI = 0.920; TLI = 0.908; SRMR = 0.046). Sex-related differential item functioning was observed in two items of the environment factor, two items of the psychological health factor and two items of the physical health factor. CONCLUSIONS: After some modifications to the measurement model, the WHOQOL-BREF shows a satisfactory fit among individuals with chronic headache in Austria. Because of these modifications and the questionnaire’s susceptibility for differential item functioning, a latent variable framework should be employed for the analysis. Future studies need to confirm these results for other language regions and should also examine different subtypes of headache.