Research Article: The Step Test Evaluation of Performance on Stairs (STEPS): Validation and reliability in a neurological disorder

Date Published: March 21, 2019

Publisher: Public Library of Science

Author(s): Anne D. Kloos, Deb A. Kegelmeyer, Katherine Ambrogi, David Kline, Meredith McCormack-Mager, Brittany Schroeder, Sandra K. Kostyk, Pedro Gonzalez-Alegre.

http://doi.org/10.1371/journal.pone.0213698

Abstract

Individuals with neurological disorders often have difficulty negotiating stairs that can lead to injurious falls. Clinicians lack a clinical tool to identify impairments in stair negotiation and to assist their decision making regarding treatment plans to improve stair performance and safety. We developed a new tool called the Step Test Evaluation of Performance on Stairs (STEPS) that is designed to assess stair performance and safety in neurological populations.

This study aimed to determine interrater and intrarater reliability of STEPS and its concurrent content validity to various clinical balance and mobility measures using individuals with Huntington’s disease (HD) as the first test population.

Forty individuals with HD (mean age 50.35) participated. Three observers rated live performances of the STEPS (interrater reliability) and seven observers rated videotaped performances twice (intrarater reliability). STEPS scores correlated with clinical mobility and balance test scores.

Excellent inter- and intrarater reliability (ICCs = 0.91 and 0.89 respectively) and good internal consistency (α = 0.83) were found. Better STEPS performance correlated with better performance on co-administered motor and mobility measures and Stair Self-Efficacy scores. Per multivariable regression analysis, the Unified Huntington’s Disease Rating Scale modified motor score and descent time were significant predictors of STEPS performance.

The STEPS tool is easy to administer, requires no special devices and can be completed in less than five minutes. In the HD test population, it shows high reliability and validity making it a potentially useful tool for assessing maneuverability and safety on stairs in HD. The results suggest that the STEPS tool warrants further study to determine STEPS cut-off values for fall prediction in HD and may prove useful as an assessment tool for other neurological disorders.

Partial Text

Stair ambulation is one of the more challenging motor activities of daily life. The ability to safely negotiate steps is an important component of the abilities needed to maintain mobility and independence both in the home and community. A recent study based on a large National Health Interview Survey identified stairs and steps as one of the three most common hazards associated with fall injuries across all age groups [1–2]. In our movement disorders clinic we have noted that patients with Huntington’s disease (HD) and Parkinson disease (PD) frequently report difficulties with stair negotiation or falls on stairs. While there are numerous clinical tests to assess gait and balance performance on flat surfaces (e.g., Tinetti [3], Timed Up and Go[4], 10-meter walk test [5]), there are no similar tests to assess performance on stairs. Specifically, there is no validated clinical assessment tool to provide clinicians with information to help identify gait impairments on stairs nor to guide clinicians’ decision making regarding treatment plans to improve stair performance and safety.

Participant (25 female, 15 male) characteristics are shown in Table 1. According to TFC scores, 11 (27.5%) of the participants were in the early disease stage (TFC 11–13), 28 (70%) were in the middle stage (TFC 3–10), and one participant (2.5%) was in the late stage (TFC 0–2). Overall, STEPS scores averaged 15.5 with standard deviation of 4.1 and ranged from 4.0 to 20.0 with 25% of patients obtaining a score of 20. Six participants reported that they were not routinely exposed to stairs. Of the 34 patients who did report stair exposure, 11 (32%) were fallers. The fallers had STEPS scores that were on average 1.7 (difference = -1.7, 95% CI:[-4.42, 1.08], p-value = 0.24) points lower than the non-fallers. The average for the non-fallers was 16.2 (95% CI:[14.7, 17.8]) and for the fallers was 14.55 (95% CI:[11.4, 17.7]) Participants were on their usual medications which included anti-choreic, antipsychotic, antidepressant, and other medications.

STEPS is the first clinical tool developed specifically to assess stair performance in individuals with neurological disorders. This study examines the reliability and validity of the STEPS tool in HD, a slowly progressive neurodegenerative disorder. Our findings show that the STEPS has excellent inter- and intrarater reliability (ICCS = 0.91 and 0.89 respectively) and good internal consistency (α = 0.83). The correlations between STEPS scores and validated clinical balance and mobility measures are moderate to excellent, demonstrating that the test has good concurrent content validity. Lower UHDRS mMSs and times to descend stairs predicted better STEPS performance scores. Taken together our findings suggest that the STEPS is a valid tool to assess stair performance in ambulatory individuals with HD.

 

Source:

http://doi.org/10.1371/journal.pone.0213698

 

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