Background To tailor physical activity treatment programs for patients with osteoarthritis, clinicians need valid and feasible measurement tools to evaluate habitual physical activity. The widely used International Physical Activity Questionnaire-Short Form (IPAQ-SF) is not previously validated in patients with osteoarthritis. Purpose To assess the concurrent criterion validity of the IPAQ-SF in patients with osteoarthritis, using an accelerometer as a criterion-method. Method Patients with osteoarthritis (n = 115) were recruited at The Division of Rheumatology and Research at Diakonhjemmet Hospital (Oslo, Norway). Physical activity was measured by patients wearing an accelerometer (ActiGraph wGT3X-BT) for seven consecutive days, followed by reporting their physical activity for the past 7 days using the IPAQ-SF. Comparison of proportions that fulfilled physical activity recommendations as measured by the two methods were tested by Pearson Chi-Square analysis. Differences in physical activity levels between the IPAQ-SF and the accelerometer were analyzed with Wilcoxon Signed-Rank Test and Spearman rank correlation test. Bland-Altman plots were used to visualize the concurrent criterion validity for total- and intensity-specific physical activity levels. Results In total, 93 patients provided complete physical activity data, mean (SD) age was 65 (8.7) years, 87% were women. According to the IPAQ-SF, 57% of the patients fulfilled the minimum physical activity recommendations compared to 31% according to the accelerometer (p = 0.043). When comparing the IPAQ-SF to the accelerometer we found significant under-reporting of total physical activity MET-minutes (p = < 0.001), sitting (p = < 0.001) and walking (p < 0.001), and significant over-reporting of moderate-to-vigorous physical activity (p < 0.001). For the different physical activity levels, correlations between the IPAQ-SF and the accelerometer ranged from rho 0.106 to 0.462. The Bland-Altman plots indicated an increased divergence between the two methods with increasing time spent on moderate-to-vigorous intensity physical activity. Conclusion Physical activity is a core treatment of osteoarthritis. Our finding that patients tend to over-report activity of higher intensity and under-report low-intensity activity and sitting-time is of clinical importance. We conclude that the concurrent criterion validity of the IPAQ-SF was weak in patients with osteoarthritis.

Background Patient organisations may be an under-utilised resource in follow-up of patients requiring long-term exercise as part of their disease management. The purpose of this study was to explore the feasibility of a web-based exercise program delivered by a patient organisation to patients with hip and/or knee osteoarthritis (OA). Methods In this pre–post feasibility study, patients aged 40–80 years with hip and/or knee OA were recruited from Diakonhjemmet Hospital. The 12-week intervention was delivered through a patient organisation’s digital platform. Feasibility was evaluated by proportion of eligible patients enrolled, proportion of enrolled patients who provided valid accelerometer data at baseline, and proportion completing the cardiorespiratory exercise test according to protocol at baseline and completed follow-up assessments. Patient acceptability was evaluated for website usability, satisfaction with the initial exercise level and comprehensibility of the exercise program. Change in clinical outcomes were assessed for physical activity, cardiorespiratory fitness and patient-reported variables. Results In total, 49 eligible patients were identified and 35 were enrolled. Thirty (86%) of these attended baseline assessments and provided valid accelerometer data and 18 (51%) completed the maximal cardiorespiratory exercise test according to protocol. Twenty-two (63%) patients completed the follow-up questionnaire, and they rated the website usability as ‘acceptable’ [median 77.5 out of 100 (IQR 56.9, 85.6)], 19 (86%) reported that the initial exercise level was ‘just right’ and 18 (82%) that the exercise program was ‘very easy’ or ’quite easy’ to comprehend. Improvement in both moderate to vigorous physical activity (mean change 16.4 min/day; 95% CI 6.9 to 25.9) and cardiorespiratory fitness, VO2peak (mean change 1.83 ml/kg/min; 95% CI 0.29 to 3.36) were found in a subgroup of 8 patients completing these tests. Across all patient-reported outcomes 24–52% of the patients had a meaningful improvement (n = 22). Conclusion A web-based exercise program delivered by a patient organisation was found to be feasible and acceptable in patients with hip and/or knee OA. Trial registration ClinicalTrials.gov, NCT04084834 (registered 10 September 2019). The Regional Committee for Medical and Health Research Ethics south-east, 2018/2198. URL: Prosjekt #632074 - Aktiv med web-basert støtte. - Cristin (registered 7 June 2019).

Already from the age of forty, people with OA have significantly shorter mean walking distance compared to matched peers, underlining the importance of early clinical approach to OA. Further, in the OA-group, the 6MWD was significantly associated with arterial stiffness, suggesting that walking ability is important for the CVD risk profile in OA. This article is protected by copyright. All rights reserved.