Background
Thyroid nodules are common in the general population and 5-10% of these nodules are
malignant, making the thyroid nodules clinically very important. It is crucial to have accurate
diagnosis of the thyroid nodule in order to provide the best appropriate treatment option. One
of the most important diagnostic tools amongst other ones, is fine-needle aspiration (FNA)
cytology. To evaluate the results of FNA, different reporting systems exist.
Methods
This study presents a comparison of diagnostic accuracy between a 5-tier and 6-tier (Bethesda)
reporting systems that have been used in Lausanne University Hospital. This study included 266
patients in 5-tier system collected between 2004-2014 and 167 patients in the 6-tier system
collected from 2014-2017.
Results
Statistical analysis was performed on different categories of the two systems in order to properly
compare the efficiencies of these two systems. Negative predictive values for the benign
categories and positive predictive values for malignant, suspicious for malignancy and follicular
neoplasm categories were similar between the two systems. However, false positive and false
negative rates of the two reporting systems were significantly different from each other.
Conclusion
Taking all the analysis in consideration, this study cannot conclusively determine whether the 5-
tier system or 6-tier system has been more efficient in the institute of interest while indicating
that both of the systems are efficient in diagnosis of thyroid nodules, shown by the high negative
predictive values, positive predictive values and high sensitivities in both of the reporting
systems.