Quality of life in non-melanoma skin cancer - The skin cancer quality of life (SCQoL) questionnaire

Background Disease-specific quality of life (QoL) questionnaires are increasingly used to provide patient-reported out-come measures in both malignant and non-malignant disease. Objective To create, validate and test the psychometrics of the Skin Cancer Quality of Life (SCQoL), which was designed to measure health-related QoL in patients with non-melanoma skin cancer affecting any area and undergoing any therapy. Methods and Materials The SCQoL was developed in a stepwise approach. Three pilot studies (testing content and face validity) and psychometric testing (scale structure, reliability, domains and known-groups validity, concurrent and convergent validity) were conducted. Rasch analyses were performed on the final questionnaire. Results The initial 10-item questionnaire was reduced to 9 items following interviews and inter-item correlations. The nine item scale was confirmed by Item Response Theory (IRT) and internal consistency. Differential Item Functioning (DIF) was found for a single item, but the effect was small. Conclusion The final 9-item SCQoL is unidimensional and consists of 3 domains covering function, emotions and control. Furthermore there is one single global item. The total score range from 0 to 27. Higher score denote a greater impairment of the QoL.