Defining the minimal clinically important difference for olfactory outcomes in the surgical treatment of chronic rhinosinusitis

Abstract

BACKGROUND Olfactory dysfunction is a common and defining symptom of chronic rhinosinusitis (CRS). Many measures of olfactory dysfunction in CRS are limited by scoring criteria defined within general populations with interpretations of statistical significance to infer clinically meaningful improvement. This investigation defines a minimal clinically important difference (MCID) for the Brief Smell Identification Test (BSIT) in CRS patients electing endoscopic sinus surgery (ESS). METHODS A multi-center cohort of 290 adult patients electing ESS for medically recalcitrant CRS were prospectively enrolled between March, 2011 and June, 2015 and completed BSIT evaluations before and after ESS. Distribution and anchor-based analytic approaches were utilized to define MCID values of the BSIT across patient cofactors. RESULTS A total of 92 (~32%) patients were found to have preoperative olfactory dysfunction (BSIT<9); significantly associated with nasal polyposis (χ2=35.0; p<0.001). The effect size distribution-based approach identified 1.0 as a MCID criterion value between “small” and “medium” effect (range: 0.61–1.52) overall. Significant mean postoperative change (∆M) was reported for patients with olfactory dysfunction (∆M=2.28; p<0.001), both with (n=54; ∆M=2.52; p<0.001) and without (n=38; ∆M=1.95; p<0.001) nasal polyposis, significantly exceeding the MCID criterion. Anchor-based approaches with regression modeling confirmed associations between MCID values and postoperative changes to olfactory-specific, survey responses (p<0.001). CONCLUSIONS Clinically meaningful change in BSIT scores may be defined as an absolute value difference of at least 1.0 unit for heterogeneous patients electing ESS for CRS. Significantly exceeding that criterion may be restricted to CRS patients with baseline olfactory dysfunction, regardless of nasal polyposis.

Investigating the minimal clinically important difference for SNOT‐22 symptom domains in surgically managed chronic rhinosinusitis

“…In our analysis health utility as measured by the SF-6D did not provide sufficient diagnostic utility to perform a robust anchor-based analysis, in contrast to prior work by our group investigating the Brief Smell Identification Test (BSIT), in which a successful anchor-based approach was used to confirm the distribution-based findings. 30 Nevertheless, having a frame of reference to interpret the clinical significance of changes in PROM scores has significant utility in outcomes research, and the previously discussed agreement of our mean scores with widely accepted anchor-based measures of the MCID lends credibility to the distribution approach in this particular case and offers a useful benchmark to interpret domain score changes.…”

Olfactory outcomes after endoscopic skull base surgery: A systematic review and meta‐analysis

“…Although the lack of statistical significance may be due to the inadequate power of studies included in the meta‐analysis, even a statistically significant change of −1.03 on the UPSIT and −0.77 on the CCSIT would be unlikely to be clinically significant. Previous studies have defined the minimal clinically important difference of both scores to be about a 10% change in the UPSIT and a change of 1 on the CCSIT …”

“…Previous studies have defined the minimal clinically important difference of both scores to be about a 10% change in the UPSIT and a change of 1 on the CCSIT. 13,46,48 Results from studies that compare olfaction outcomes with or without harvesting of NSF have been conflicting. A previous comment by Greig et al suggested that NSF elevation likely leads to impairment in objective measures of olfaction, whereas ESBS without elevation of NSF only leads to transient reduction in olfaction.…”

Does Medical Therapy Improve SinoNasal Outcomes Test–22 Domain Scores? An Analysis of Clinically Important Differences

“…Third, these reported MCID values are reflective of current standards of care for both medical and surgical therapy, and may not hold true if significant shifts in either treatment modality occur in the future, such as increased use of biologics for CRS or similar targeted therapies . Fourth, an anchor‐based determination of the MCID was not able to be performed in this study, which could assist in independently confirming the distribution‐based findings . Fifth, CAMT was left to the discretion of each individual practitioner by design, thus introducing potential heterogeneity to the medical treatment arm.…”

“…11 Fourth, an anchor-based determination of the MCID was not able to be performed in this study, which could assist in independently confirming the distribution-based findings. 25 Fifth, CAMT was left to the discretion of each individual practitioner by design, thus introducing potential heterogeneity to the medical treatment arm. This was chosen to allow providers the flexibility to select treatments as the clinical picture of the patient evolved, but it does limit generalizability compared to the surgical cohort, where there is more standardization of treatment.…”