Intra-observer and inter-observer repeatability of two slowness tests: Moberg picking-up and Twelve-ball tests

Slowness plays a crucial role in geriatric assessments and is closely linked to frailty. In an attempt to propose alternatives to gait speed, the Moberg picking-up test (MPUT) was proposed for measuring slowness in older adults. Concurrently, we developed the Twelve-ball test (TBT) as a novel and simplified alternative to the MPUT. This study aimed to assess and compare the intra-observer and inter-observer repeatability of the MPUT and TBT in a large sample of community dwelling older adults.

This study used data from the population-based Lausanne cohort 65+. In 2020, 596 individuals, aged 81-86 years, completed two sets of MPUT or TBT measurements. Intraclass correlation coefficients (ICCs) and 95% confidence intervals (CI) were used to examine intra-observer (two-way mixed-effects model) and inter-observer (one-way random-effects model) relative repeatability of both measurements for either the MPUT or TBT. Absolute repeatability was determined by the standard error of measurement (SEM). Bland-Altman plots were plotted for visual representation of heteroscedasticity. Subgroup analyses were conducted per gender, education, and speed.

For the MPUT, intra-observer repeatability was ICC = 0.77 (95% CI 0.65 to 0.84) and SEM = 1.76, while inter-observer repeatability was ICC = 0.74 (95% CI 0.66 to 0.80) and SEM = 1.23. For the TBT, intra-observer repeatability was ICC = 0.89 (95% CI 0.80 to 0.93) and SEM = 0.91, while inter-observer repeatability was ICC = 0.84 (95% CI 0.78 to 0.89) and SEM = 0.91. In all subgroup analyses, the TBT exhibited higher intra-observer and inter-observer repeatability compared to the MPUT.

The MPUT and TBT appear reliable in terms of intra- and inter-observer repeatability. However, the assessments of repeatability, considering both relative and absolute consistency, show stronger results in the TBT compared to the MPUT test. With its simplified application, the TBT proves to be a promising measure of slowness in older adults.