Understanding the pain experience in hip and knee osteoarthritis – an OARSI/OMERACT initiative

Objective. To examine the pain experience of people with hip or knee osteoarthritis (OA), particularly changes over time and most distressing features. Method. Focus groups in individuals aged 40+ years with painful hip or knee OA obtained detailed descriptions of OA pain from early to late disease. A modified Patient Generated Index (PGI) was used to assess the features of OA pain that participants found most distressing. Content analysis was performed to examine response patterns; descriptive statistics were used to summarize PGI responses. Results. Mean age of the 143 participants (52 hip OA; 91 knee OA) was 69.5 years (47–92 years); 60.8% were female and 93.7% Caucasian. Participants described two distinct types of pain – a dull, aching pain, which became more constant over time, punctuated increasingly with short episodes of a more intense, often unpredictable, emotionally draining pain. The latter, but not the former, resulted in significant avoidance of social and recreational activities. From PGI responses, distressing pain features were: the pain itself (particularly intense and unpredictable pain) and the pain's impact on mobility, mood and sleep. Conclusions. Two distinct pain types were identified. Intermittent intense pain, particularly when unpredictable, had the greatest impact on quality of life.