Development and Preliminary Evaluation of a Quality-of-Life Questionnaire for Adults with Neurofibromatosis Type 1 (NF1-AdQOL)

Background Neurofibromatosis type 1 (NF1) is a variable and unpredictable multisystem genetic disorder which predisposes to medical complications, cognitive impairment and disfigurement, of all which can impact negatively upon the health related quality of life (HRQOL) of affected adults. Objectives To develop and validate a disease specific HRQOL adult questionnaire to evaluate effects of NF1 from the patient's viewpoint. Methods The NF1 adult HRQOL questionnaire (NF1-AdQOL) was developed based on patient interviews (n=8), survey of clinicians and piloting of the questionnaire. Adults with NF1 (n=114, 18-40 years) were recruited from three Australian genetics clinics and completed the NF1-AdQOL, Skindex-29 and Short Form-36v2 (SF-36v2) questionnaires. An exploratory factor analysis of the NF1-AdQOL was conducted to assess construct validity. Convergent and discriminant validity of the NF1-AdQOL was determined by using the multi-trait multi-method with Skindex-29 and SF-36v2 scores. Results Factor analysis indicated that 62.7% of the common variance could be explained by three factors labelled as 'emotions associated with cosmetic appearance' (12 items), 'social functioning and learning' (11 items) and 'physical symptoms' (8 items). NF1-AdQOL had good internal consistency (Cronbach's α = 0.96). Convergent validity was confirmed by moderate associations with similarly named scales of the Skindex-29 and SF-36v2. Results from all HRQOL questionnaires indicated overall healthy HRQOL for young adults with NF1. Conclusions NF1-AdQOL is a relatively valid, feasible and fairly easy to read tool to measure QOL in adults with NF1. Further evaluation is required to determine its test-retest reliability, responsiveness and validity in larger adult NF1 cohorts.