Sensitivity analysis and diagnostic accuracy of the Brief Smell Identification Test in patients with chronic rhinosinusitis

BackgroundThe Brief Smell Identification Test (BSIT) is an abbreviated version of the Smell Identification Test (SIT) used to assess olfactory function. Although the BSIT can be efficiently administered in under 5 minutes, the accuracy of the BSIT in relation to the SIT in patients with chronic rhinosinusitis (CRS) is unknown. MethodsPatients with CRS were recruited as part of an ongoing multi-institutional observational cohort study. A total of 183 participants provided both BSIT and SIT olfactory function scores during initial enrollment. Linear associations between BSIT and SIT scores were evaluated using Pearson's correlation coefficients (r(p)). The sensitivity, specificity, and accuracy of BSIT scores were determined using SIT scores as the gold standard. ResultsA strong bivariate linear association was found between BSIT and SIT scores (r(p) = 0.893; p < 0.001) for all participants. A significantly lower proportion of patients were identified as having abnormal olfaction using the BSIT compared to the SIT (47% vs 68%, respectively; p < 0.001). Using the currently defined score of 8 as a cut-point for abnormal olfactory function, the BSIT demonstrated a sensitivity of 63% and specificity of 88% with an overall accuracy of 71%. Increasing the cut-point to 9 resulted in an increased sensitivity of 86%, a specificity of 76%, and an improved overall accuracy of 83%. ConclusionIn patients with CRS, BSIT scores strongly correlate with SIT scores; however, the BSIT underestimates olfactory dysfunction as defined by the suggested cut-point of 8. Increasing the cut-point to 9 increased the sensitivity and accuracy of the BSIT.