Fig. 1

Two-by-two table examining the primary outcome. Definitions of true and false positives and negatives comparing fine needle aspiration biopsy (FNAB) to the final diagnosis based on surgical histopathology or non-surgical clinical follow-up. Positive and negative results of index test (FNAB) separated into non-benign and benign. Positive and negative results of reference test (surgical histopathology or non-surgical clinical follow-up) separated into malignant and non-malignant. TN true negative, FN false negative, FP false positive, TP true positive, FNAB fine needle aspiration biopsy