Clinical validation of self-reported osteoarthritis

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.

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.

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.

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.