Objective: To evaluate the psychometric properties of the Neuropsychiatric Fluctuations Scale (NFS) in patients with Parkinson’s disease (PD) using classical test theory (CTT) and item-response theory (Rasch analysis) methods.
Background: The NFS, designed to ascertain the severity of neuropsychiatric symptoms, consists of 20 items grouped in two subscales for Off- and On-states (theoretical range 0-30).
Method: In this International, multi-center, cross-sectional study, patients with PD were recruited from movement disorders clinics across seven European countries. Clinical assessment included Hoehn & Yahr (HY) stage, MDS-UPDRS and PDQ-8. For CTT, reliability (internal consistency and test-retest) and construct validity were calculated. According to Rasch analysis, fit to the model, unidimensionality, item local independence, reliability and differential item functioning (DIF) by language of administration (English, French, German, Greek, Romanian, and Spanish) were analyzed.
Results: A total of 303 patients were included (203 with motor fluctuations, PF; 100 with no motor fluctuations, PnF). For the NFS-Off subscale, mean scores were: 14.98 (standard deviation, SD: 7.1) for PF in Off; 6.97 (SD: 7.2) for PF in On; and 3.90 (SD: 4.3) for PnF (p<0.001). For the NFS-On subscale, mean scores were: 8.16 (SD: 6.0) for PF in Off; 17.95 (SD: 7.5) for PF in On; and 20.01 (SD: 6.5) for PnF (p<0.001). Internal consistency (Cronbach’s alpha) was >0.70 in both subscales and test-retest reliability (intra-class correlation coefficient) was 0.59 for NFS-Off and 0.70 for NFS-On. The NFS-Off subscale correlated 0.30-0.41 with MDS-UPDRS Part IV (Motor fluctuations) and 0.42-0.49 with PDQ-8 Summary Index (SI). The NFS-On subscale correlated -0.21 – -0.27 with MDS-UPDRS Part IV, and -0.33 – -0.35 with PDQ-8 SI. Both subscales showed significantly higher scores in PF in more severe HY stages. NFS-Off showed good fit to Rasch model, unidimensionality and no DIF. NFS-On fitted the Rasch model after rescoring items 2, 11 and 13 and removing items 6 and 17. After these modifications, it was unidimensional and showed no DIF.
Conclusion: The NFS has acceptable psychometric properties and could be a useful tool for assessing neuropsychiatric fluctuations in patients with PD in clinical practice and research, which is essential for furthering our understanding of the pathophysiology of PD and developing effective treatments.
To cite this abstract in AMA style:
I. Debove, C. Rodriguez-Blazquez, A. Zenger, A. Ayala, M. Bereau, S. Bostantjopoulou, KR. Chaudhuri, MA. Qamar, E. Cubo, B. Falkenburger, C. Falup-Pecurariu, MJ. Forjaz, MM. Kurtis, H. Reichmann, P. Krack, P. Martinez-Martin. International validation of the Neuropsychiatric Fluctuations Scale in patients with Parkinson’s disease [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/international-validation-of-the-neuropsychiatric-fluctuations-scale-in-patients-with-parkinsons-disease/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/international-validation-of-the-neuropsychiatric-fluctuations-scale-in-patients-with-parkinsons-disease/