Agreement between clinical and radiological methods of diagnosing knee osteoarthritis

Objective: To determine the agreement between clinical diagnosis and different radiological grading scales of knee osteoarthritis (OA) in an epidemiological study. Methods: Health 2000 Survey is an extensive population study focusing on major health problems in a representative sample of 8028 Finns over 30 years of age. In the survey, physicians diagnosed knee OA on the basis of physical status, symptoms, and medical history. A total of 130 participants (mean age 60 years, 68% female) were re-examined 1 year later (Kuopio OA 2000 Study) to determine the agreement between clinical and radiological diagnosis as well as between three different radiological grading scales (Kellgren and Lawrence, Ahlback, and Piperno). Weight-bearing knee radiographs were taken and graded by a radiologist in Kuopio University Hospital. The history of knee symptoms was obtained using the Western Ontario MacMaster (WOMAC) and Lequesne questionnaires. Results: Knee OA was diagnosed clinically in 17.7% and radiologically in 24.6-30% of participants. The strength of agreement was moderate (kappa values 0.34-0.54) between the clinical and the radiological diagnosis and substantial (0.62-0.78) between the different radiological scales. Those subjects identified by any diagnostic method as having OA in either knee reported significantly more symptoms and disability than the other subjects. Conclusion: The agreement between the clinical diagnosis performed in a large population study and radiological grading scales was only moderate. By contrast, the agreement between different radiological scales was substantial.