Abstract
BackgroundThe proper reliability analysis for specific type of data and limit study of various types of construct validity are crucial for performance-based tests for the knee osteoarthritis (OA) population. The purpose of this study was to evaluate relative and absolute reliability and construct validity of the Osteoarthritis Research Society International (OARSI) recommended minimal core set of performance-based tests in knee OA in community-dwelling adults.MethodsFifty-five primary knee OA (median age 69.0, interquartile range [IQR] 11.0) participated in the cross-sectional study. Three performance-based tests were performed in two sessions with a 1-week interval; 30-s chair stand test, 40-m fast-paced walk test and 9-step stair climb test. Relative reliability included intra-class correlation and Spearman’s correlation coefficient (SPC). Absolute reliability included standard error of measurement, minimum detectable change, coefficient of variance, limit of agreement (LOA) and ratio LOA. Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS), knee extensor strength and pain scale were analysed for convergent validity using Pearson’s correlation coefficient and SPC. Analysis of Covariance was utilised for known-groups validity.ResultsRelative and absolute reliability were all acceptable. LOA showed small systematic bias. Acceptable construct validity was only found with knee extensor strength. All tests demonstrated known-groups validity with medium to large effect size.ConclusionThe OARSI minimum core set of performance-based tests demonstrated acceptable relative and absolute reliability and good known-groups validity but poor convergent validity.
Highlights
Knee osteoarthritis (OA) is the deteriorative risk to locomotive function and consequential frailty [1–2]
24 were excluded who did not meet American College of Rheumatology (ACR) criteria (n = 7), had history of knee trauma (n = 4) and total knee replacement (n = 4), had knee pain related with spinal conditions (n = 2), other knee pathology, i.e. gout (n = 1) and rheumatoid arthritis (n = 2), were prone to fatigue and weak from coronary artery disease (n = 2), had chronic obstructive pulmonary disease (n = 1) and was unable to provide responses to personal medical history, pain scale and ACR questionnaire (n = 1)
Notes: 30-s chair stand test (30sCST) = 30-s chair-stand test; 40mFPWT = 40-m fast-paced walk test; 9-step SCT= 9-step stair climb test; Ln = natural log transformation; back-transformed = antilog or exponent; ICC = intra-class correlation coefficient; 95% CI SEM (95% CI) = 95% confidence interval; SEM = standard error of measurement; MDC90 = minimum detectable change at the 90% CI level; coefficient of variance (CV)% = coefficient of variation percentage; LOA = limit of agreement; ageometric mean; bSpearman’s correlation coefficient; cratio LOA
Summary
Knee osteoarthritis (OA) is the deteriorative risk to locomotive function and consequential frailty [1–2]. The minimal core set of three performance-based tests were recommended by the Osteoarthritis Research. Society International (OARSI), which includes 30-s chair stand test (30sCST), 40-m fast-paced walk test (40mFPWT) and stair climb test (SCT) [3, 5]. Stair negotiation is one of the most difficult tasks to overcome. It is associated with the limit of function from sarcopenia, somatosensory and visual impairment and other disorders such as OA [9]. The proper reliability analysis for specific type of data and limit study of various types of construct validity are crucial for performance-based tests for the knee osteoarthritis (OA) population. The purpose of this study was to evaluate relative and absolute reliability and construct validity of the Osteoarthritis Research Society International (OARSI) recommended minimal core set of performance-based tests in knee OA in community-dwelling adults
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