Diagnostic test evaluation parameters for fine-needle aspiration cytology among visible thyroid swellings

FNAC has outgrown as a diagnostic tool in thyroid swellings. However, the routine parameters are influenced by the prevalence of the disease which is high among hospital based studies. Diagnostic Parameters not influenced by the disease prevalence need to be analysed among local population Aim: To Assess the Diagnostic Parameters of FNAC among visible thyroid swellings Settings and Design: Hospital Based cross sectional study Methods and Materials: Two hundred and thirty specimens from visible thyroid swelling of patients consulting the Medicine, Surgery and ENT departments from January 2012 to July 2014 were analysed. The study was undertaken during the period from January 2012 to July 2014. Clinical grading of thyroid swelling was confirmed and data analysed with EPIINFO version 7. Statistical analysis used: Sensitivity, Specificity, Likelihood Ratio, weighted Likelihood Ratio, Pre and Post Test Probability, Kappa statistics. Results: Of the 230 cases of thyroid lesions, 194 were cases of non-neoplastic lesions and 36 cases of neoplastic lesions on FNAC. The concordance of the diagnosis for neoplastic and non-neoplastic lesions comparing histopathology as gold standard was 65.71% and 89.23% respectively. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and diagnostic accuracy for FNAC with respect to neoplastic & non-neoplastic lesions in thyroid in the present study are 40-74.38%, 94.87%, 58.33-72.22%, 10.1943.81%, 0.77-14.28, 0.27-0.63 and 86.50-91.74% respectively. For neoplastic lesions, the weighted likelihood ratio Positive is 2.5689 and weighted likelihood ratio Negative is 0.11. For non-neoplastic lesions, the weighted likelihood ratio Positive is 1.4 and weighted likelihood ratio Negative is 0.11. Conclusions: The weighted LR+ indicates there is 2.6 times more possibility of a neoplastic lesion compared to 0.11 times possibility of a negative result. FNAC being an excellent, rapid diagnostic procedure with high degree of accuracy, and high likelihood ratios, would be of immense benefit among cases with thyroid swelling