The reliability of clinical tonsil size grading in children

Because tonsillar enlargement can have substantial ill health effects in children, reliable monitoring and documentation of tonsil size is necessary in clinical settings. Tonsil grading scales potentially allow clinicians to precisely record and communicate changes in tonsil size, but their reliability in a clinical setting has not been studied.

To assess the interobserver and intraobserver reliability of the Brodsky and Friedman tonsil size grading scales and a novel 3-grade scale.

Cross-sectional study between June 2012 and August 2013 at a tertiary pediatric otolaryngology outpatient clinic at British Columbia Children's Hospital. We recruited 116 children, aged 3 to 14 years, with no major craniofacial abnormalities. For each child, 2 separate tonsil assessments (with at least a 5-minute interval in between) were conducted by 4 independent observers: 2 staff pediatric otolaryngologists, 1 otolaryngology trainee (fellow or resident), and 1 medical student. Each observer assessed and graded tonsil sizes using 3 different scales.

Interobserver and intraobserver reliabilities were assessed by deriving the intraclass correlation coefficients (ICCs) and Pearson correlation coefficients, respectively. To discount for any asymmetric scores, all data analysis was conducted on the left tonsil measurement only.

Mean interobserver reliability was highest for the Brodsky grading scale (ICC, 0.721; Cronbach α, 0.911), followed by the Friedman grading scale (ICC, 0.647; Cronbach α, 0.879) and the 3-grade scale (ICC, 0.599; Cronbach α, 0.857). The mean intraobserver reliabilities for the Brodsky, Friedman, and modified 3-grade scales were 0.954, 0.932, and 0.927, respectively.

The Brodsky grading scale offered the highest interobserver and intraobserver reliability when compared with the Friedman and novel 3-grade scales. The results of this study would support the uniform use of the Brodsky scale for future clinical and research work.