An experiment in reducing interobserver variability of the examination for joint tenderness.

This experiment was designed to test the feasibility of reducing interobserver variability of the joint examination by agreement on a standard examination. Six rheumatologists independently examined 6 patients with rheumatoid arthritis (RA) in predetermined order, before and after a standardization of examination techniques. Results of an analysis of variance showed a reduction of the percent of variability due to observers from 13.8%, before standardization, to 3.2% after standardization, and an improvement in the percent variability related to patient differences from 70.7%, before standardization, to 86.3% after standardization. Such a reduction in observer variability has a potential for allowing a reduction in sample sizes required for RA clinical trials.