COMPARING MEASURES OF RELIABILITY FOR INDEXES OF GINGIVITIS AND PLAQUE

THE PURPOSE OF THIS METHODOLOGICAL STUDY was to compare methods used t o assess reliability for gingival inflammation and plaque. Duplicate e xaminations were conducted by one examiner on 17 subjects (506 scoring sites), using the gingival index (GI), bleeding points index (BPI), a nd plaque index (PI). The percentage of agreement, the weighted and un weighted kappa coefficients, and Pearson correlation coefficients were calculated as statistics of reliability for mesial buccal site scores and whole mouth mean scores when appropriate. For mesial buccal sites the respective values of the. GI, BPI, and PI for weighted kappas wer e: 0.47, 0.49, and 0.75; for the correlation coefficients: 0.47, 0.49, and 0.76; for unweighted kappas, 0.39, 0.39, and 0.39; and for percen tage of agreement 66.2%, 76.1%, and 51.2%;. For whole mouth means the correlation coefficients for the GI, BPI, and PI were 0.87, 0.59, and 0.87, respectively. In conclusion, the most useful statistics in asses sing the intraexaminer reliability of a solo examiner in descending or der were the weighted kappa coefficient, Pearson correlation coefficie nt, the unweighted kappa coefficient, and percentage of agreement.