Validation of a New Scale of Balance Recovery Confidence for Community-dwelling Older Adults

Introduction: Patient-reported outcome measures (PROMs) provide clinicians with a greater understanding of patients' perceived ability in their physical performance. Existing PROMs on falls efficacy provide meaningful information about the perceived ability in older people to perform common activities of daily living without falling. However, the perceived ability to recover the balance from a slip, a trip, or volitional movements has been inadequately assessed. Balance recovery confidence relates to the judgement of self-reactive ability. The scale of balance recovery confidence (BRC) is a new PROM that measures perceived balance recovery self-efficacy. The purpose of the study protocol is to describe the first psychometric evaluation of BRC's measurement properties.

Methods and analysis: This study is a validation phase of a newly developed PROM conducted in Singapore. Two hundred community-dwelling older adults, aged 65 years and older, will complete five self-reported instruments (BRC), Activities-specific Balance Confidence Scale (ABC), Falls Efficacy Scale-International (FES-I), Late-Life Function and Disability Instrument-Function (LLDI-F) and Global Perceived Effect (GPE) and three performance measures (Hand strength dynamometer, 30-second Chair Stand, Mini BESTest). Classical test theory methods will assess acceptability, data completeness, targeting of the items, scaling assumptions, internal consistency reliability and construct validity. Factor analysis will establish unidimensionality. Rasch analysis will evaluate item fit, differential item functioning, response scale ordering, targeting of persons and items and the reliability.

Introduction: This study aims to conduct the first evaluation of measurement properties in the scale of balance recovery confidence. There are several measurement properties such as unidimensionality, validity (to what extent does the instrument measure the construct it purports to measure) and reliability (the degree to which measurement is free from error) of the PROM that is needed to be studied.

This psychometric validation aims to provide evidence that the PROM can be purposefully used in practice, given that rigorous methods have been applied for the development and validation of the BRC. For the study, balance recovery confidence is defined as the perceived ability to recover one's balance from perturbations, such as a slip, a trip, or a loss of balance that can occur in common, everyday activities. This focus will leave little ambiguity about precisely what is being measured. The resulting questionnaire is intended to be approximately 20 questions and should not take longer than 10 min to complete. The instrument is not intended to be used as a diagnostic tool of impaired specific balance recovery mechanisms. The BRC allows clinicians and researchers to quantifiably determine the balance recovery confidence in older adults and use the scale as a conduit for understanding older people's perspectives when encountering different perturbations during their daily activities.

The objectives are to:

1. To evaluate the measurement properties of the BRC, i.e. acceptability, targeting, scaling assumptions and reliability using Classical Test Theory (CTT), the internal scale structure using Rasch measurement theory in the Singapore community-dwelling older adults.
2. To assess the construct validity of the refined BRC against commonly used PROMs and performance measures in the Singapore community-dwelling older adults.
3. To refine the items, response categories, and scale structure of the BRC using Rasch measurement theory in an English-speaking sample of community-dwelling older adults in Singapore.

Methods: Participants will attend two sessions in the study. In the first session, the researcher will use a measurement data form to record the participants' results of four questionnaires: BRC, ABC, FES-I, LLFDI-F and three performance measures: Jamar hand strength dynamometer, 30-second chair stand test and Mini BESTest. After seven days, participants will attend the second session to complete the BRC, and the GPE scale which will be used to ensure participants' perception of their abilities remained unchanged during the seven days. The time interval of 7-day had been reported to be sufficient to minimise recall bias. Participants will be asked if they have had experienced a fall, near-fall, or encountered any incident that might affect their balance recovery ability over the past seven days.

Statistical analysis: Quantitative data will be analysed and interpreted through two measurement test theories using IBM SPSS Statistic V.26.0 and Winsteps V.4.5.0. Classical test theory is a traditional quantitative approach to test the validity and reliability of a scale based on its items. This approach is based on the assumption that every observed score is a function of an individual's true score and random error. In contrast, RA works on the probability of a person's level on an item is a function of the person's ability and of the difficulty of the item. RA evaluates a scale against a mathematical measurement model and analyses the scale at the level of each item, and each person. Measurement properties including unidimensionality, internal structure, validity and reliability will be evaluated.

Eligibility Criteria:
Inclusion Criteria:

* 65-years and older,
* Living in the community,
* Functionally independent with or without the use of a walking aid and be able to read,
* Write and communicate in English.

Exclusion Criteria:

* Require any physical assistance from another person to walk within the home,
* Presenting with clinical observable severe cognitive impairment.
* Unable to provide written consent to participate in the study