Examiner bias: influence of patient history on perceptual ratings of videostroboscopy

Videostroboscopic assessment of the vocal folds is a technique that relies solely on the subjective visual perception of the clinician. The purpose of the present study was to evaluate whether clinicians' videostroboscopic judgment of the vocal folds was influenced by their patients' case histories. The presence of bias was studied by assigning 30 videostroboscopic images of vocal folds to 19 experienced speech pathologists and otolaryngologists who received either good, bad, or no case histories accompanying the images. It was found that, as hypothesized, patient history is a possible source of bias. Post hoc analyses permitted the observation that experienced clinicians are less prone to bias than less-experienced clinicians, and that bias mostly occurs with mildly pathologic larynges. Further research is warranted to localize and quantify the presence of bias in order to determine whether a change in the clinical protocol is necessary.