Development and Content Validation of Novel Patient-Reported Outcome Measures to Assess Disease Severity and Change in Patients with Erythropoietic Protoporphyria: The EPP Impact Questionnaire (EPIQ)

Abstract

Purpose Erythropoietic protoporphyria (EPP), a rare inherited disorder, presents in early childhood with severe, painful phototoxicity, with significant impacts on health-related quality of life (HRQoL). Previous studies have not captured all concepts important to patients. Therefore, this study sought to develop a novel, comprehensive, and content valid patient-reported outcome (PRO) measure to assess the efficacy of new therapies. Patients and Methods Qualitative interviews were conducted with EPP participants and clinical experts to obtain views on concepts relevant to patients. Results informed the development of novel PROs, which were debriefed during subsequent combined concept elicitation and cognitive debriefing interviews. Results Twenty-three interviews were conducted with 17 adults and 6 adolescents with EPP. Concept elicitation revealed that participants experienced many symptoms with significant variability. The most common were burning, pain, swelling, and tingling. Tingling was the most common prodromal symptom, while burning was the most bothersome, and pain was the worst full reaction symptom. Participants reported being negatively impacted in their ability to do daily activities, and social and emotional functioning. Many reported impacted ability to work and be productive at their job. Participants reviewed and completed the newly developed PRO measures assessing full reactions and ability to do activities, as well as items to assess severity and change in severity of prodromal symptoms, full reactions, and EPP overall. All measures were found to be comprehensive, clear, and relevant. Conclusion PRO measures are needed to assess important aspects of HRQoL and evaluate therapeutic response. These PRO measures are unique in assessing overall severity and change in EPP.

Content validity of SarQoL, a quality of life questionnaire specific to sarcopenia

“…Efforts were made to recruit participants representing the full spectrum of sarcopenic patients, including those suffering from severe sarcopenia. In line with the COSMIN methodology and based on original studies with similar aims to this study [ 5 , 10 , 11 ], we set an initial sample size of 20 participants as the target sample. However, to ensure adequacy, concept saturation was examined [ 5 ] and interviews were conducted until complete concept saturation was observed.…”