Analysis of the discordance between radiographic changes and knee pain in osteoarthritis of the knee

OBJECTIVE: To analyze cross sectional data from the National Health and Nutrition Examination Survey (NHANES I) concerning 3 indicators of osteoarthritis (OA) of the knee: radiographic evidence of structural damage, self-reported knee pain, and self-report of a diagnosis of arthritis at any joint by a physician. METHODS: Analysis of NHANES I data for 6880 persons ages 25-74 in the United States. RESULTS: Radiographic stage 2-4 knee OA was found in 319 subjects (3.7%); only 47% of these individuals reported knee pain, and only 61% reported that a physician had told them that they had arthritis. Knee pain was reported by 1004 subjects (14.6%), only 15% of whom had radiographic stage 2-4 changes of OA, and 59% of whom reported having a diagnosis of arthritis by a physician. A report of arthritis diagnosed by a physician was given by 1762 subjects (25.6%), of whom only 11% had stage 2-4 radiographic knee OA and 34% reported knee pain. CONCLUSION: Substantial discordance exists in this population based study between radiographic OA of the knee versus knee pain, versus a diagnosis of arthritis by a physician. These phenomena may be important in the design of clinical research studies, as well as in criteria for OA.