Objective: This study aims to evaluate the psychometric properties of the Mild Behavioral Impairment-Checklist (MBI-C) in Parkinson’s Disease (PD) using Rasch measurement theory.

Background: The MBI-C was developed to identify individuals at risk for cognitive decline and dementia by assessing neuropsychiatric symptoms across five domains. However, a previous validation of the instrument in PD suggested discrepancies in the scale’s sensitivity to differentiate levels of symptom severity. This study examines the MBI-C through the lens of Rasch measurement theory (RMT) to further explore its validity.

Method: Rasch analysis was conducted on a nationwide Canadian sample of individuals with PD using a generalized partial credit model. Unidimensionality of domains was assessed, and response category functioning was examined at the item level. The suitability of the items for measuring the target construct was also evaluated. Furthermore, an interpretational threshold score for the MBI-C in PD was calculated using the Rasch model, with an anchor item representing cognitive impairment (based on MoCA score) to identify individuals at risk.

Results: The sample included 830 participants (64.3% male) with a mean age of 67 years (SD = 9) and a median disease duration of 4 years (IQR: 2–8). All five domains met the criteria for unidimensionality. Despite the presence of floor effects, the 24 items displayed strong discriminative ability, effectively distinguishing between participants with varying levels of symptom severity. Specific items within the social inappropriateness and abnormal perception or thoughts domains demonstrated disordered categories and required a higher level of symptom severity for endorsement (difficulty > 2 logits). Through the RMT framework, an interpretational threshold of 4|5 was identified for the MBI-C, beyond which cognitive impairment is likely to occur.

Conclusion: The MBI-C shows potential for rapidly assessing the neurobehavioral correlates of cognitive impairment in PD. As seen in multiple instruments in the field of PD, some items displayed difficulty for endorsement, potentially contributing to their floor effects. These findings suggest that the instrument’s response system and/or item wording could be optimized, particularly when assessing people living with PD and mild to moderate MBI.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-complexity-of-neuropsychiatric-symptoms-assessment-in-parkinsons-disease-a-rasch-analysis-of-the-mild-behavioral-impairment-checklist/