CHECK, a multicenter cohort of persons with early osteoarthritis

The course of complaints, prognosis and underlying mechanisms in the early stage of osteoarthritis is poorly understood. To address the many gaps in these areas, the Dutch Arthritis Foundation (DAF) initiated and funded an inception cohort of patients with early symptomatic osteoarthritis of the hip and/or knee: CHECK (Cohort Hip & Cohort Knee). CHECK set out to study clinical, biochemical and radiographic signs and symptoms of early OA with 10-year follow-up of 1,000 persons. In this thesis we describe that rapid joint damage (change of ≥2 grades on a radiological score in 5 years) is related to worsening of pain and function. In participants with slow progression (radiological change of 1 grade or less), pain and physical function remain fairly stable over 5 year. We noted that especially comorbidities, such as additional problems in musculoskeletal system and obesity, but also mental status may have a negative effect on pain and physical health status. We studied possible differences in evolution of disease characteristics within CHECK participants in two relevant areas: the clinical hallmark pain and the radiological hallmark osteophytes. We concluded that on group level the evolution of pain remains fairly stable, but a considerable individual variation was found. Within this heterogeneous population we identified three homogeneous subgroups of pain trajectories in patients with symptomatic knee OA. Participants of the ‘good outcome’ trajectory (n=222) had a slight decrease in pain severity over time and ended up with lower pain severity. Participants of the ‘moderate outcome’ trajectory (n=294) had a variable course over time with moderate pain. The ‘poor outcome’ trajectory participants (n=189) had an increase of pain severity over time. These trajectories of pain could be characterized by different clinical features, coping strategies and lifestyle factors. Participants who had at baseline a BMI above 25, and/or who had a lower education, had 3 or more comorbidities, had additional hip pain, and/or used the coping strategies ‘worrying’ and ‘resting’ were more likely to have a poor outcome. Apart from these baseline characteristics the poor outcome trajectory was also associated with rapid joint damage (change of ≥2 grades on a radiological score in 5 years ). The same method was used to identify homogeneous subgroups regarding the formation of osteophytes over 5 years. Three homogeneous subgroups of osteophyte formation could be identified, but in most participants the course of osteophyte formation over a period of 5 years was relatively flat. In the management of pain in early OA, the physician should not only take joint damage at that moment into account, but also changes over a period of time. Also attention should be given to personal and environmental factors (such as coping, comorbidities, education). In conclusion, better (or more specific) characterization of the patients’ symptoms, contextual factors (personal and environmental) and of the damaged tissue is needed, to improve our ability to target the right treatment to the right patient, resulting in improved outcome