Study Design for Calibration of Clinical Examiners Measuring Periodontal Parameters

• Autores: Ryan E. Wiegand, Carlos F. Salinas, Elizabeth G. Hill, Elizabeth H. Slate, Sara Grossi
• Localización: Journal of periodontology, ISSN 0022-3492, Vol. 77, Nº. 7, 2006, págs. 1129-1141
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Study Design for Calibration of Clinical Examiners Measuring Periodontal Parameters Elizabeth G. Hill,* Elizabeth H. Slate,* Ryan E. Wiegand,* Sara G. Grossi,† and Carlos F. Salinas‡ *Department of Biostatistics, Bioinformatics, and Epidemiology, Medical University of South Carolina, Charleston, SC.

    †Currently, Brody School of Medicine, East Carolina University, Greenville, NC; previously, School of Dental Medicine, State University of New York, Buffalo, NY.

    ‡College of Dental Medicine, Medical University of South Carolina.

    Correspondence: Dr. Elizabeth G. Hill, Department of Biostatistics, Bioinformatics, and Epidemiology, Medical University of South Carolina, P.O. Box 250835, 135 Cannon St., Suite 303, Charleston, SC 29425. Fax: 843/876-1126; e-mail: hille@musc.edu.

    Background: We present an approach to examiner calibration study design where the number of calibration subjects is based on a specified margin of error (half-width of the 95% confidence interval [CI]) of the percentage of agreement (exact and within 1 mm) for both intra- and interexaminer reliability assessments.

    Methods: An experienced standard examiner (S) trained three dental hygienists (A, B, and C) in correct procedures for obtaining a variety of periodontal measures. Duplicate measurements of probing depth (PD [mm]) and the free gingival margin to the cemento-enamel junction (CEJ-GM [mm]) were obtained in a pilot study to design a formal examiner calibration study, where sample sizes were adjusted for the effects of within-subject clustering of binary indices of agreement.

    Results: Within-subject clustering of agreement indices resulted in an approximate four-fold increase in the variance of the estimates of percentage of agreement with the standard. PD and CEJ-GM percentage of exact agreement measurements (95% CI) for each examiner-standard pair, respectively, were as follows: AS = 55% (48%, 61%) and 70% (62%, 78%); BS = 52% (45%, 59%) and 73% (63%, 82%); and CS = 55% (50%, 61%) and 72% (65%, 79%). The corresponding 95% CIs unadjusted for the effects of clustering underestimated the margin of error associated with the estimates of exact agreement by as much as 57% for PD and 68% for CEJ-GM.

    Conclusion: Failure to account for dependence among site-level agreement indices results in a false sense of precision in the resulting reliability estimates and can lead to faulty inference.