Probing the effect of OSCE checklist length on inter-observer reliability and observer accuracy

PURPOSE The Objective Structured Clinical Examination (OSCE) is a widely employed tool for measuring clinical competence. In the drive toward comprehensive assessment, OSCE stations and checklists may become increasingly complex. The objective of this study was to probe inter-observer reliability and observer accuracy as a function of OSCE checklist length. METHOD Study participants included emergency physicians and senior residents in Emergency Medicine at Dalhousie University. Participants watched an identical series of four, scripted, standardized videos enacting 10-min OSCE stations and completed corresponding assessment checklists. Each participating observer was provided with a random combination of two 40-item and two 20-item checklists. A panel of physicians scored the scenarios through repeated video review to determine the 'gold standard' checklist scores. RESULTS Fifty-seven observers completed 228 assessment checklists. Mean observer accuracy ranged from 73 to 93% (14.6-18.7/20), with an overall accuracy of 86% (17.2/20), and inter-rater reliability range of 58-78%. After controlling for station and individual variation, no effect was observed regarding the number of checklist items on overall accuracy (p=0.2305). Consistency in ratings was calculated using intraclass correlation coefficient and demonstrated no significant difference in consistency between the 20- and 40-item checklists (ranged from 0.432 to 0.781, p-values from 0.56 to 0.73). CONCLUSIONS The addition of 20 checklist items to a core list of 20 items in an OSCE assessment checklist does not appear to impact observer accuracy or inter-rater reliability.