Reliability study of outcome measures in subjects with knee osteoarthritis

Abstract

Objective: The purpose of this study was to examine the reliability of the Western Ontario and McMaster Universities Osteoarthritis (WOMAC), visual analog scale (VAS), pressure pain threshold (PPT), Timed Up and Go test (TUG) and Quadriceps & Hamstrings strength in patients with knee osteoarthritis.

Materials and Methods: Test-retest reliability of measurements with 1 day interval between session was determined by an Intraclass-correlation coefficient (ICC), Standard error of measurements (SEMs) and Coefficient of variation (CV) in 20 patients with knee osteoarthritis (age 63.5±9.9 years, weight 62.2±10.11 kg., height 156.6±8.58 cm.)

Results: Intra tester reliability of outcome measures were good to excellent with intraclass correlation coefficient (ICC) of greater than 0.86, Standard error of measurements (SEMs) of less than 0.61% and Coefficient of variation (CV) of less than 9.38%, except the WOMAC (subpart: function) that exceeded 15%.

Conclusion: These measurement outcomes were reliability and could be useful for detecting changes in management of knee osteoarthritis (OA). However, the WOMAC (sub part: function) seemed to be less reliable due to its variation. Therefore, other potential functional outcome measures should be considered to add in for detecting change in the part of function outcome.

Bull Chiang Mai Assoc Med Sci 2015; 48(2): 107-114. Doi: 10.14456/jams.2015.8