The Quality of Life in Hand Eczema Questionnaire (QOLHEQ): validation of the German version of a new disease-specific measure of quality of life for patients with hand eczema

Abstract

Health-related quality of life (HRQOL) is widely used as a patient-reported outcome to evaluate clinical trials. In routine care it can also be used to improve treatment strategies or to enhance patients' self-awareness and empowerment. Therefore a disease-specific instrument is needed that assesses in detail all the impairments caused by the disease of interest. For patients with hand eczema (HE) such an instrument was developed by an international expert group, but its measurement properties are unknown. To validate the German version of the Quality of Life in Hand Eczema Questionnaire (QOLHEQ), which covers the domains of (i) symptoms, (ii) emotions, (iii) functioning and (iv) treatment and prevention. The QOLHEQ was assessed up to three times in 316 patients with HE to test reliability and sensitivity to change. To test construct validity we also assessed several reference measures. The scale structure was analysed using the Rasch model for each subscale and a structural equation model was used to test the multi domain structure of the QOLHEQ. After minor adaptions of the scoring structure, all four subscales of the QOLHEQ did not significantly misfit the Rasch model (α>0·05). The fit indices of the structural equation model showed a good fit of the multi domain construct with four subscales assessing HRQOL. Nearly all a priori-defined hypotheses relating to construct validity could be confirmed. The QOLHEQ showed a sensitivity to change that was superior compared with all reference measures. The QOLHEQ is ready to be used in its German version as a sensitive outcome measure in clinical trials and for routine monitoring. The treatment-relevant subscales enable its use to enhance patients' self-awareness and to monitor treatment decisions.