Clinical validation of self-reported osteoarthritis

Objective: To evaluate the use of a postal survey to detect subjects in the community with osteoarthritis (OA) and the ability of metrologists to detect clinical OA. Methods: Questionnaires were posted to a random sample of residents of the Northern Sydney Health Area, aged 45-64 years old, asking for details of musculoskeletal complaints and diagnoses. A questionnaire definition of OA was made if 'osteoarthritis' was reported or 'degenerative arthritis', 'joints wearing' out together with pain in joints during the previous 6 months. Hands, hips, and knees of 106 subjects were examined by one of two trained metrologists according to ACR clinical criteria for OA. A second subsample was examined by two metrologists and two rheumatologists independently to test for inter-observer variation. Data were analyzed for percentage agreement and concordance using the kappa statistic. Results: After two mailouts, 59% responded (526 males and 796 females). Definite OA (excluding spine alone) was reported by 52 males (10%), 155 females (19.5%) and possible OA by 62 males (11.8%), 164 females (20.6%). Following examination, 81% of self-reported 'definite' OA was confirmed, while 57% of 'possibles' and one self-reported 'negative' were determined to have clinical OA. Reporting of specific joint OA was less reliable than the highly reliable self-reporting of general OA. Good agreement was demonstrated between rheumatologists and metrologists in the clinical diagnosis. Conclusion: Postal questionnaires have the potential to detect OA in the community. The clinical diagnosis can be confirmed by a trained metrologist. Further evaluation of this instrument is warranted in other populations.