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

Abstract

Background The 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. Methods Patients 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 (rp). Sensitivity and specificity of BSIT scores were determined using SIT scores as the ‘gold standard’. Results A strong bivariate linear association was found between BSIT and SIT scores (rp=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%. Conclusion In 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.

Comparison of surgical outcomes between patients with unilateral and bilateral chronic rhinosinusitis

“…Typically, improvements in olfaction are seen following ESS among patients with olfactory dysfunction, and anosmia and nasal polyposis have been associated with greater improvements. 25,26,28 In this study, bilateral and unilateral groups had mean preoperative BSIT scores of 10.6 and 9.5, respectively, both in the normal range above 9.0, 17,18 which may have explained this lack of improvement. 28 …”

“…Total BSIT scores ≤ 8 are clinically interpreted as either reduced olfactory identification capacity or patient malingering, although alternative scoring thresholds have been proposed for subjects with CRS. 16–18 …”

Analysis of factors associated with electing endoscopic sinus surgery

“…Total BSIT scores ≥ 9 can be clinically interpreted as normal olfaction for healthy subjects of all ages using gender‐adjusted, adult, normative data. Lower BSIT scores (≤ 8) clinically can be interpreted as either some degree of olfactory dysfunction or potential malingering; however, alternative interpretations of threshold scores for the BSIT have been suggested for patients with CRS …”

“…Lower BSIT scores ( 8) clinically can be interpreted as either some degree of olfactory dysfunction or potential malingering 12 ; however, alternative interpretations of threshold scores for the BSIT have been suggested for patients with CRS. 13…”

Is greater antibiotic therapy prior to ESS associated with differences in surgical outcomes in CRS?

“…Study participants also provided high‐resolution computed tomography (CT) radiographic imaging of the paranasal sinuses preoperatively, for which each enrolling physician reviewed images and staged each scan using the Lund‐Mackay scoring system . Olfactory function and detection was measured during each study evaluation time point using the Brief Smell Identification Test (BSIT) (Sensonics, Inc., Haddon Heights, NJ), for which higher BSIT total scores (score range: 0–12) reflect a better sense of smell …”