Objective: To describe the osteoarthritis (OA) study population of CHECK (Cohort Hip & Cohort Knee) in comparison with relevant selections of the study population of the OAI (OA Initiative) based on clinical status and radiographic parameters.
Methods: In the Netherlands a prospective 10-year follow-up study was initiated by the Dutch Arthritis Association on participants with early OA related complaints of hip and/or knee: CHECK. Parallel in the US an observational 4-year follow-up study, the OAI, was started by the NIH, on patients with or at risk for symptomatic knee OA. For comparison with CHECK, the entire cohort and a subgroup of individuals excluding those with exclusively hip pain were compared with relevant subpopulations of the OAI.
Results: At baseline, CHECK included 1002 participants with in general similar characteristics as described for the OAI. However, significantly less individuals in CHECK had radiographic knee OA, at baseline when compared to the OAI (p<0.0001). In contrast, at baseline, the CHECK cohort reported higher scores on pain, stiffness, and function disability (WOMAC) when compared to the OAI (all p<0.0001). These differences were supported by physical health status that in contrast to mental health (SF-36/-12) was at baseline significantly worse for the CHECK participants (p<0.0001).
Conclusion: Although both cohorts focus on the early phase of OA, both cohorts differ significantly with respect to structural (radiographic) and clinical (health status) characteristics, CHECK expectedly representing participants in an even earlier phase of disease.