Interobserver Variation in the Assessment of Thyroid Enlargement: A Pitfall in Surveys of the Prevalence of Endemic Goitre

Abstract

An important concern in surveys of the prevalence of endemic goitre is the possibility of inaccuracy that can occur when estimating thyroid enlargement by clinical examination. We report here the results of a study from central Africa that demonstrated the importance of interobserver variation in the assessment of goitre size among experts and participants attending an international training course on iodine deficiency disorders (IDD). Agreement among raters estimated by calculation of the kappa statistic was poor on average when the five-stage goitre classification recommended by WHO was used. As expected, agreement on a single category was slightly better, especially when the category of interest was visible goitre. Our results suggest that palpation alone is not a reliable method for assessing the severity of IDD endemia. Other sources of inaccuracies are discussed and recommendations are made for better data collection on IDD in Africa and other regions.