Clinical instruments for bedside functional assessment: Convergent validity among the AM-PAC '6-Clicks' and BMAT

Abstract

Aims and objectives: To determine the level of convergent validity of the '6-Clicks' Basic Mobility and Daily Activity with the Bedside Mobility Assessment Tool (BMAT) in patients admitted to a tertiary care academic hospital.

Background: Accurately measuring a patient's ability to mobilise during hospitalisation is necessary but can be challenging. Two instruments, the Activity Measure for Post-Acute Care short-form '6-Clicks' and the BMAT, are commonly used to determine patients' mobility levels; however, these instruments have not been psychometrically evaluated together. Understanding the characteristics between these tools can support the process of shared decision making amongst healthcare providers.

Design: Retrospective Cohort adhering to the STROBE statement.

Methods: Using 13,498 individual patient admissions from an electronic health record, the BMAT score measured closest in time to the '6-Clicks' Basic Mobility and Daily Activity evaluation was collected. Spearman rank correlations with 95% confidence intervals (CIs) were calculated to determine the level of convergent validity between the '6-Clicks' Basic Mobility and Daily Activity with the BMAT. Pairwise correlations were also calculated and stratified by admitting medical service.

Results: All correlations for the '6-Clicks' Basic Mobility or Daily Activity summative scores and the BMAT mobility levels were statistically significant and moderately correlated. The weakest correlations were seen within the Orthopaedic admitting service group. Most correlations stratified by admitting service [CVD/Pulmonary, Medicine/Hospitalist, Other Surgery and Solid Organ Transplant] were moderate. The strongest correlations were seen within the Neuro/Stroke admitting service.

Conclusion: Moderate levels of convergent validity exist between the '6-Clicks' and the BMAT in this sample. These findings demonstrate that the construct of patient mobility is not being assessed similarly between the two instruments.

Relevance to clinical practice: These findings suggest the continued use of both instruments to allow interdisciplinary assessment of patient mobility status during a hospital stay.

Keywords: construct; correlation; function; movement; psychometrics.