A clinimetric evaluation of the problem behaviors assessment short form (PBA-s) within the context of the Huntington's disease integrated staging system (HD-ISS)

Abstract

Background/Objective:

This study extends prior clinimetric evaluations by examining the factor structure, internal consistency, and distributional properties of the Problem Behaviors Assessment – Short Form (PBA-s) in a large sample of people with Huntington's disease (pwHD) at various stages of progression using the Huntington's Disease Integrated Staging System (HD-ISS) framework.

Methods:

Baseline PBA-s item total scores were analyzed from 14,371 Enroll-HD participants. Using HD-ISS criteria, participants were categorized as Stage 0/1 (n = 3262; 23%), Stage 2 (n = 1722; 12%), or Stage 3 (n = 9387; 65%).

Results:

Missing responses were low across items and stages. Item total score distributions demonstrated significant skew in Stages 0/1 and 2. Within Stage 3, skewness was less prevalent but still present in most distributions. In all groups, the PBA-s demonstrated moderate internal consistency, though five items exhibited weak item-total correlations. Resultant factor structures differed from those previously reported and varied by HD-ISS stage. In Stages 0/1 and 2, a three-factor model representing internalizing, externalizing, and cognitive control problems accounted for 39–42% of the total variance. In Stage 3, a five-factor solution explained 56% of the overall variance and consisted of internalizing, externalizing, cognitive control problems, suicidality, and cognitive dysfunction.

Conclusions:

While the PBA-s demonstrates adequate internal consistency, our results revealed high rates of non-endorsement (i.e., item total scores = 0) and a variable factor structure with disease progression. Thus, the PBA-s may not distinguish mild changes in behavioral symptoms that might occur in early HD-ISS stages of disease.

Plain language summary

Behavioral symptoms are a feature of Huntington's disease (HD) associated with reduced quality of life for people with HD (pwHD) and their families. Reliable and valid assessment of these symptoms are essential for the proper characterization of their frequency, severity, and longitudinal course. In this paper, we examine the measurement properties of an HD-specific measure of behavioral symptoms, the Problem Behaviors Assessment – Short Form (PBA-s). We extend prior investigations by assessing the PBA-s across stages of disease using Huntington's Disease Integrated Staging System (HD-ISS) framework. Results reveal a low level of symptom endorsement across all PBA-s items in earlier stages and a shift in symptom clustering with disease progression. These findings indicate the PBA-s may not capture minimal or mild behavioral changes that might occur in earlier stages of HD.