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Barker K.1,2, Moore M.1, Schlussel M.3, Newman M.1
1Oxford University Hospitals Foundation Trust, Nuffield Orthopaedic Centre, Oxford, United Kingdom, 2University of Oxford, NDORMS, Oxford, United Kingdom, 3University of Oxford, Centre for Statistics in Medicine, Oxford, United Kingdom
Background: The Figure of 8 Walk Test (F8W) was designed to provide a measure of gait representative of walking in everyday life which involves navigating both straight and curved paths. The validity of the test has previously been reported in a clinic setting with older adults with no lower limb pain or muscle weakness. To date it has not been reported in a community setting.
Purpose: To determine the validity and reliability of the F8W test for patients post knee replacement surgery when used in a community setting.
Methods: Seventy four individuals one year following knee replacement surgery participated in this observational study involving two assessments more than one week apart. Assessments were carried out in either the physiotherapy clinic or participants homes with subjects being randomised into one of the two groups. The F8W time, steps, smoothness score and boundary limits were recorded along with Timed up and Go (TUG) time and a Timed Walk Test (TWT). A second visit was conducted with two assessors independently recording the results. The time taken to complete each test was standardised using Z scores and the agreement between each test with the F8W test time was reported on Bland and Altman plots. Both Inter-rater and Intra-rater reliability were calculated by taking the variability of scores for the time to complete the F8W test and plotting them against the mean time to complete the test for each subject. Bland and Altman plots were again produced to show the respective limits of agreement.
Results: There were no significant differences in the component scores for the F8W test by setting in which the testing occurred. Confidence intervals do not suggest that the assessment setting had an important influence in the variability of any parameter of the investigated assessments. Intra-rater correlations were high for the overall sample (r = 0.926) and for subgroups (r = 0.925 home and 0.932 -physiotherapy clinic). High correlation coefficients were also found for inter-rater reliability overall sample (r = 0.961) and for subgroups (r = 0.965 - home and 0.957 - physiotherapy clinic).
The total time to complete test (TTCT) correlated highly for F8W test and TUG and TWT. There was more variation in the agreement between testers for accuracy with disagreement about whether 4 participants had strayed outside of the 0.6 metre boundary. Both assessors agreed 62 participants had a smoothness score of 3 but categorised the other 12 differently between categories 1 and 2.
Conclusion(s): The F8W test is a reliable assessment in a sample of elderly people following knee replacement irrespective of setting. When standardised for the different distances walked in each test, a high level of agreement was seen for the TTCTs from the F8W and TUG and TWT.
Implications: The F8W test can detect small changes in gait in the elderly, inclusion of the accuracy component may be desirable correlating with poorer function on other domains of the tests and potentially being a surrogate for falls risk.
Funding acknowledgements: This study was funded by the National Institute for Health Research Health Technology Assessment programme (HTA 12/196/08).
Topic: Musculoskeletal
Ethics approval: The study protocol was approved by South Central Research Ethics Committee, UK [Reference 15/SC/0019]
All authors, affiliations and abstracts have been published as submitted.
