Objective: To assess the prognostic value of the clinical American College of Rheumatism (ACR) classification criteria of knee osteoarthritis (OA) on persisting knee complaints and increase of disability in adult patients with knee pain in general practice after 1-year follow-up.
Methods: Patients (aged >35 years) consulting for non-traumatic knee complaints in general practice were enrolled in the study. At baseline and 1-year follow-up knee complaints and function were assessed by questionnaires and a physical examination was performed. The prognostic value of fulfilling the clinical ACR criteria of knee OA at baseline on the outcomes persisting knee complaints and increase of disability was determined.
Results: 549 patients were included in the study of which 480 (87.4%) were available for follow-up. The studied population consisted of 236 (49.2%) women with mean age 53.6 [standard deviation (sd) 11.3], mean body mass index (BMI) 27.1 (sd 4.2), 288 (60.0%) patients had payed employment, and 292 (60.8%) patients fulfilled the clinical ACR criteria of knee OA. After 1-year follow-up, 236 (49.2%) patients reported persisting knee complaints, and 84 (17.5%) reported an increase of disability. There was no association of fulfilling the clinical ACR criteria of knee OA at baseline with persisting knee complaints [odds ratio (OR) 1.15; 95% Confidence Interval (CI) 0.80; 1.67] or increase of disability (OR 1.05; 95% CI 0.43; 2.58) at follow-up.
Conclusion: The clinical ACR classification criteria of knee OA have no prognostic value for predicting persisting knee complaints or an increase of disability at 1-year of follow-up in adult patients with non-traumatic knee complaints in GP.