Functional Gait Assessment in Persons with Idiopathic Normal Pressure Hydrocephalus: Analyzing Total Scores and Item Difficulties Through Rasch Analysis

Hideyuki Urakami, Yohei Okada, Yoshinaga Kajimoto, Ayumu Yasuda, Yuki Kawami, Ryuichi Saura, Kazuki Kudo, Naoya Ishida, Yasutaka Nikaido
Purpose:

This study aimed to determine the logarithmic values of the total score and the difficulty levels of sub-items in the FGA for PwiNPH through Rasch analysis.


Methods:

One hundred eighty-eight PwiNPH (age: 77.1 ± 5.3 years [116 males, 72 females]) with a positive result on the cerebrospinal fluid tap test (TT) according to the iNPH diagnosis criteria participated in this study. Persons with other comorbid neurological or orthopedic disorders interfering with gait and those unable to walk unassisted for at least 10 meters were excluded in advance. Participants were assessed using the FGA under natural conditions (i.e., before TT or any treatment). The FGA consists of 10 items, with each item scored from 0 to 3 points, resulting in a total score of 30 points, where higher scores are associated with better balance function. The obtained data were analyzed using Rasch modeling with WINSTEPS® software. Rasch analysis is a method to convert ordinal scores into interval measures. This conversion allows for the positioning of items along a continuum of difficulty in an ordered and measured sequence, indicating the relative distance between items in interval units.

Results:

The FGA score for all PwiNPH was 14.3 ± 5.5. The ability of PwiNPH ranged widely, from -8.07 logits (FGA score = 2) to 8.10 logits (FGA score = 28), with a mean logit value of 0.17 (FGA score = 15), indicating significant variability in balance function among individuals. The difficulty of items ranged from the easiest item ("Gait and pivot turn") at -2.58 logits to the most difficult item ("Gait with narrow base of support") at 5.35 logits. Other items were positioned as follows: "Stair steps" at -2.38 logits, "Change in gait speed" at -2.35 logits, "Gait with vertical head turns" at -1.82 logits, "Gait level surface" at -1.17 logits, "Step over obstacle" at -0.51 logits, "Gait with horizontal head turns" at 0.12 logits, "Ambulating backward" at 1.95 logits, and "Gait with eyes closed" at 3.39 logits.

Conclusion(s):

The findings enhance the understanding of the FGA's structure and its use in evaluating dynamic balance in PwiNPH, contributing to early diagnosis and targeted treatment strategies. Future research should validate these findings in larger, diverse populations and explore the relationship between FGA sub-items and fall risk in PwiNPH.

Implications:

Understanding the difficulty hierarchy of FGA sub-items allows clinicians to tailor assessments and interventions for PwiNPH. These insights promote precise and reliable evaluation and treatment planning, facilitating optimal management of PwiNPH.

Funding acknowledgements:
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Keywords:
Functional Gait Assessment
Idiopathic Normal Pressure Hydrocephalus
Rasch Analysis
Primary topic:
Neurology
Second topic:
Education: clinical
Third topic:
Other
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
The study was approved by the ethics committee of Osaka Medical and Pharmaceutical University, and all participants provided informed consent.
Provide the ethics approval number:
No. 2341
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

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