Non-Motor Fluctuations in Parkinson's Disease: Validation of the Non-Motor Fluctuation Assessment Questionnaire

Background In patients with Parkinson's disease (PD), sleep, mood, cognitive, autonomic, and other non-motor symptoms may fluctuate in a manner similar to motor symptoms. Objectives To validate a final version of a patient-rated questionnaire that captures the presence and severity of non-motor fluctuations in levodopa-treated PD patients (NoMoFA). Methods We recruited PD subjects from five movement disorders centers across the US and Canada. We assessed the internal consistency, floor and ceiling effects, test-retest reliability, and concurrent validity of NoMoFA. Classical test theory and item response theory methods informed item reduction and Delphi process yielded a final questionnaire. Results Two hundred subjects and their care-partners participated in the study (age: 66.4 +/- 9.6 years; disease duration: 9 +/- 5.5 years; median Hoehn and Yahr [H&Y] OFF: 3 [range 1-5]; mean Unified Parkinson's Disease Rating Scale (UPDRS) III ON score: 27.4 +/- 14.9). Acceptability of the scale was adequate. There were floor effects in 8/28 items. Cronbach's alpha was 0.894. While eight items had "item-to-total" correlations below the cutoff of 0.4, removing these items did not improve Cronbach's alpha. Test-retest reliability was acceptable (intraclass correlation coefficient [ICC] 0.73; 95% confidence interval, 0.64-0.80). Concurrent validity was adequate with all Spearman's rho values comparing NoMoFA score to other measures of parkinsonian severity showing significance and in the expected direction. A final Delphi panel eliminated one item to avoid redundancy. Conclusions The final 27-item self-administered NoMoFA is a valid and reliable questionnaire, capturing both static and fluctuating non-motor symptoms in PD. (c) 2021 International Parkinson and Movement Disorder Society