Partial Verification Distorts Estimates of Sensitivity in Diagnostic Accuracy Studies for Fine-Needle Aspiration Cytology

Excerpt

We wish to comment on the study by Ahn et al. entitled “Surgeon-Performed Ultrasound-Guided Fine-Needle Aspiration Cytology of Head and Neck Mass Lesions: Sampling Adequacy and Diagnostic Accuracy” published in Annals of Surgical Oncology.1 In this study, 617 patients presented for fine-needle aspiration (FNA), of whom 131 were verified by histopathology; only these cases were included in the diagnostic accuracy calculations. Unfortunately, this type of study design is common in FNA studies and generally produces biased estimates of both sensitivity and specificity, known as partial verification bias,2 which arises when the verification rate of positive and negative samples differ. This generally occurs in FNA studies because positive findings are more often referred to surgery and receive histological verification, while negative findings are managed (and verified) clinically. Thus, when studies only include cases that receive histological verification, positive cases are verified at a higher rate than negative cases. Verification bias has been shown to be common in FNA diagnostic accuracy studies, particularly studies relating to head and neck tumors.3,4 …