Grading of tenderness as a source of interrater error in the Ritchie articular index
Hart, L.E.; Tugwell, P.; Buchanan, W.W.; Norman, G.R.; Grace, E.M.; Southwell, D.
Journal of Rheumatology 12(4): 716-717
1985
ISSN/ISBN: 0315-162X PMID: 4057194 Document Number: 253446
To assess the effect of grading of tenderness on the interrater reliability of the Ritchie articular index (RAI), 3 physicians recorded independent joint scores on each of 18 patients, examined in random order. Our results indicate that close agreement (Intraclass Correlation Coefficient = 0.85) can be achieved on global RAI scores, and that raters can achieve reasonable agreement (kappa = 0.40-0.59) on the absolute presence or absence of tenderness of individual joints. By contrast, interrater agreement hardly exceeds the chance level (kappa = 0.008-0.148) when degree of tenderness is independently assessed. The grading system of the RAI may thus be implicated as an important source of the instrument's interrater error.