JIMD Reports, Volume 37

Nina A. Zeltner, Matthias R. Baumgartner, Aljona Bondarenko, Regina Ensenauer, Daniela Karall, Stefan Kölker, Chris Mühlhausen, Sabine Scholl-Bürgi, Eva Thimm, Julia Quitmann, Peter Burgard, Markus A. Landolt, Martina Huemer, Zeltner, Nina A., Baumgartner, Matthias R., Bondarenko, Aljona, Ensenauer, Regina, Karall, Daniela, Kölker, Stefan, Mühlhausen, Chris, Scholl-Bürgi, Sabine, Thimm, Eva, Quitmann, Julia, Burgard, Peter, Landolt, Markus A., Huemer, Martina

This study is part of the "European network and registry for intoxication type metabolic diseases" (E-IMD) project. Intoxication-type inborn errors of metabolism (IT-IEM) such as urea cycle disorders (UCD) and organic acidurias (OA) have a major impact on patients' lives. Patients have to adhere to strict diet and medication and may suffer from metabolic crises and neurocognitive impairment. Disease-specific health-related quality of life (HrQoL) assessment questionnaires are the method of choice to estimate the subjective burden of a disease. To date, no such instrument is available for IT-IEM. Disease-specific patient- and parent-reported HrQoL questions were constructed in German based on focus group interviews with patients and parents. Questionnaires for patients from 8 to 18 years were piloted with 14 participants (n = 9 children and adolescents, n = 5 parents) by cognitive debriefing and tested psychometrically with 80 participants (n = 38 patients, n = 42 parents) for item characteristics, validity, and reliability to construct the first version of a disease-specific HrQoL questionnaire. Twenty-eight questions were selected based on item descriptives. Scales of self- and proxy questionnaires demonstrated acceptable to excellent reliability in terms of internal consistency (Cronbach's α = 0.70-0.93). Scales and total scores correlated with those of generic HrQoL questionnaires, showing convergent validity. The MetabQoL 1.0 questionnaire exhibits sound psychometric properties and is a promising step towards assessing patient-reported outcomes in research and clinical practice. It provides a solid basis for translation into other languages and further elaboration and psychometric exploration in larger populations.