Approaches to describing inter-rater reliability of the overall clinical appearance of febrile infants and toddlers in the emergency department.

Objectives. To measure inter-rater agreement of overall clinical appearance of febrile children aged less than 24 months and to compare methods for doing so. Study Design and Setting. We performed an observational study of inter-rater reliability of the assessment of febrile children in a county hospital emergency department serving a mixed urban and rural population. Two emergency medicine healthcare providers independently evaluated the overall clinical appearance of children less than 24 months of age who had presented for fever. They recorded the initial 'gestalt' assessment of whether or not the child was ill appearing or if they were unsure. They then repeated this assessment after examining the child. Each rater was blinded to the other's assessment. Our primary analysis was graphical. We also calculated Cohen's κ, Gwet's agreement coefficient and other measures of agreement and weighted variants of these. We examined the effect of time between exams and patient and provider characteristics on inter-rater agreement. Results. We analyzed 159 of the 173 patients enrolled. Median age was 9.5 months (lower and upper quartiles 4.9-14.6), 99/159 (62%) were boys and 22/159 (14%) were admitted. Overall 118/159 (74%) and 119/159 (75%) were classified as well appearing on initial 'gestalt' impression by both examiners. Summary statistics varied from 0.223 for weighted κ to 0.635 for Gwet's AC2. Inter rater agreement was affected by the time interval between the evaluations and the age of the child but not by the experience levels of the rater pairs. Classifications of 'not ill appearing' were more reliable than others. Conclusion. The inter-rater reliability of emergency providers' assessment of overall clinical appearance was adequate when described graphically and by Gwet's AC. Different summary statistics yield different results for the same dataset.