Towards developing diagnostic criteria for early knee osteoarthritis: data from the CHECK study.

OBJECTIVES There is a general consensus that a shift in focus towards early diagnosis and treatment of knee OA is warranted. However, there are no validated and widely accepted diagnostic criteria for early knee OA available. The current study aimed to take the first steps towards developing diagnostic criteria for early knee OA. METHODS Data of 761 individuals with 1185 symptomatic knees at baseline were selected from the CHECK study. For CHECK, individuals with pain/stiffness of the knee, aged 45-65 years, who had no prior consultation or a first consultation with the general practitioner for these symptoms in the past 6 months were recruited and followed for 10 years. A group of 36 experts (17 general practitioners and 19 secondary care physicians) evaluated the medical records in pairs to diagnose the presence of clinically relevant knee OA 5-10 years after enrolment. A backward selection methods was used to create predictive models based on pre-defined baseline factors from history taking, physical examination, radiography and blood testing, using the experts' diagnoses as gold standard outcome. RESULTS Prevalence of clinically relevant knee OA during follow-up was 37%. Created models contained 7-11 baseline factors and obtained an area under the curve between 0.746 (0.002) and 0.764 (0.002). CONCLUSION The obtained diagnostic models for early knee OA had 'fair' predictive ability in individuals presenting with knee pain in primary care. Further modelling and validation of the identified predictive factors is required to obtain clinically feasible and relevant diagnostic criteria for early knee OA.