Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Although physical function is one of the core outcome domains in knee osteoarthritis (OA), the ability of a measurement instrument to detect changes over time in the construct (physical function) being measured, i.e. the responsiveness, has never been tested as currently recommended by the Consensus-based Standards for the selection of health status Measurement Instruments (COSMIN)1. The aim of the current study was to compare the responsiveness of physical function between four commonly used disease-specific patient related outcome measures in patients with knee OA following currently recommended standards.
Patients with knee OA fulfilling the clinical ACR criteria and receiving conservative treatment following a stepped care approach were invited to complete a set of questionnaires at baseline and three months. Questionnaires included four commonly used measures of physical function ie Knee Injury and Osteoarthritis Outcome Function Short Form (KOOS-PS), the Lequesne Algofunctional index (LAI), Lower Extremity Functional Scale (LEFS), and Western Ontario and McMaster University Osteoarthritis Index Physical Function subscale (WOMAC-PF). Responsiveness of physical function was investigated according to the COSMIN standard by testing 15 a priori defined hypotheses formulated by an expert group regarding expected correlations between changes in physical function with changes in other (un)related measures (pain, fatigue, self-efficacy, coping, anxiety, depression and mental health) or expected differences in correlation. Responsiveness was considered positive if > 75% of the hypotheses could be confirmed.
Of the 161 included patients, the majority was female (61%), with a mean age of 59 years and a body mass index of 29.7 kg/m2. We could confirm 12 out of 15 predefined hypotheses (80%) about expected correlations using the physical function subscale of the WOMAC. For the KOOS-PS, LAI and LEFS respectively 11 (73%), 10 (67%) and 11 (73%) hypotheses could be confirmed.
This is the first study that evaluated and compared the responsiveness of physical function measured with KOOS-PS, LAI, LEFS and WOMAC-PF according to the latest COSMIN standards1. Our results suggest that the WOMAC-PF is potentially better able to detect changes over time in physical function than the LAI, LEFS and KOOS-PS in a population of patients with knee OA receiving conservative treatment. We therefore recommend the WOMAC-PF subscale should be the measure of first choice in in clinical trials evaluating the effectiveness of an intervention in knee OA patients.
To cite this abstract in AMA style:Mahler EAM, Cuperus N, Bijlsma JWJ, Vliet Vlieland T, van den Hoogen FHJ, den Broeder A, van den Ende CHM. Assessment and Comparison of Responsiveness of Four Patient Reported Outcome Measures to Assess Physical Function in Patients with Knee Osteoarthritis: WOMAC-PF Subscale Responds Best [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). http://acrabstracts.org/abstract/assessment-and-comparison-of-responsiveness-of-four-patient-reported-outcome-measures-to-assess-physical-function-in-patients-with-knee-osteoarthritis-womac-pf-subscale-responds-best/. Accessed October 22, 2017.
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