Phenotypes in Movement Behaviour of Patients with Hip and/or Knee Osteoarthritis - a cross-sectional study

Abstract

Background Osteoarthritis is one of the most common chronic joint diseases, mostly affecting the knee or hip through pain, joint stiffness and decreased physical functioning in daily life. Regular physical activity can help preserve and improve physical functioning and reduce pain in patients with osteoarthritis. Interventions aiming to improve movement behaviour can be optimized by tailoring them to a patients’ starting point; their current movement behaviour. Movement behaviour needs to be assessed in its full complexity, and therefore a multidimensional description is needed. Objectives The primary aim of this study was to identify phenotypes in movement behaviour of patients with hip and/or knee osteoarthritis. Second, differences between phenotypes regarding BMI, sex, age, physical functioning, comorbidities, fatigue and pain were determined. Design and setting In this cross-sectional study, baseline data of the clinical trial ‘e-Exercise Osteoarthritis’, collected in 143 Dutch primary care physical therapy practices, were analysed. Methods Movement behaviour was assessed with the ActiGraph GT3X and GT3X+ accelerometers. A hierarchical cluster analysis was performed in order to identify phenotypes. Second, differences between phenotypes regarding the clinical characteristics were assessed via Kruskall Wallis and Chi2 tests. Results 182 patients diagnosed with hip and/or knee osteoarthritis and with an average age of 63 years were included in this study. The analysis resulted in identification of four phenotypes: the continuously light active phenotype, the prolonged sedentary phenotype, the sedentary non-exercisers and the exercisers. The percentage of men was higher in the prolonged sedentary phenotype and the exercisers compared to the other phenotypes. Lower levels of pain and fatigue and higher levels of physical functioning were seen in the prolonged sedentary phenotype compared to the continuously light active phenotype and the sedentary non-exercisers. The exercisers experienced a higher level of physical functioning compared to the sedentary non-exercisers. Conclusions Based on multidimensional movement behaviour, four phenotypes can be identified in patients with osteoarthritis of the hip and/or knee. These have substantially different movement behaviours and clinical characteristics. Movement behaviour interventions can be improved by incorporating the knowledge about these phenotypes. Further research should test the validity of phenotypes defined here.