Assessing burden of illness following acute deep vein thrombosis: data quality, reliability and validity of the Norwegian version of VEINES-QOL/Sym, a disease-specific questionnaire.

The data quality, reliability and validity of the Norwegian version of VEINES-QOL/Sym were assessed in 74 patients with deep vein thrombosis (DVT). This patient-reported questionnaire produces two scale scores of venous disease-specific quality of life and venous symptoms. Items had low levels of missing data. Item-total correlations ranged from 0.41 to 0.78 with the exception of 0.29 for the symptom item 'night cramps'. Internal consistency was supported by Cronbach's alpha of 0.88 and 0.94 for VEINES-Sym and VEINES-QOL, respectively. Test-retest reliability assessed for 40 patients gave intraclass correlation coefficients of 0.83 and 0.88 for VEINES-Sym and VEINES-QOL, respectively. Assessment of correlation between the two scales and other clinical measures supports the construct validity of the scales. The results indicate acceptable internal consistency, test-retest reliability and validity of the Norwegian version of the VEINES-QOL/Sym questionnaire in patients with DVT. The results follow those of previous studies, and support the use of VEINES-QOL/Sym in the evaluation of patient outcomes and burden of illness in clinical studies of venous thrombosis.