Physical activity (PA) level of patients with knee osteoarthritis is lower than general population. International recommendations recommend a non-pharmacological intervention including self-management education program, weight loss and an adapted exercise program. However, there is no scale assessing the perception of PA in this population. Our purpose is to develop and validate a self-questionnaire assessing barriers and facilitators to practice regular PA in patients with knee osteoarthritis.

Semi-structured interviews identified 22 barriers and facilitators. We developed a 24 items questionnaire (evaluated by a 5-point Likert scale) completed by 548 patients with knee osteoarthritis. In addition to EPAP, patients completed 3 other questionnaires: KOFBeQ (assessing the fears and beliefs of knee osteoarthritis patients), WOMAC (assessing the severity of osteoarthritis) and IPAQ (assessing the level of physical activity). Reproductibility and sensitivity to change were evaluated by a second group of 142 patients included in a three weeks spa therapy resort.

Seven items were removed after preliminary statistical analysis. Seventeen items were grouped into four dimensions (Barriers, Facilitators, Motivations, Beliefs). The internal consistency is good for Barriers, Facilitators and Motivations dimensions (Croncach's α>0.7); intermediate for Beliefs dimension (Croncach's α=0.64). EPAP was significantly correlated with KOFBEQ and WOMAC but not with IPAQ. Reproducibility was good for all dimensions with intraclass correlation coefficients higher than 0.60. Only “Beliefs” dimension showed a significant improvement between day 1 and month 3 after spa therapy resort.

EPAP questionnaire has good psychometric properties and can help to guide the management of patients with knee ostoarthritis. It can be used in research for the evaluation of the perception of physical activity.