Minimal Clinically Important Difference of the Taiwan Smell Test in Patients with Bilateral Chronic Rhinosinusitis and Nasal Polyps Post-Sinus Surgery.

Objective: The impairment of smell has become a crucial evaluation in determining disease severity, control status, and therapeutic response in patients with chronic rhinosinusitis and nasal polyps (CRSwNP). This study aimed to evaluate the minimal clinically important difference (MCID) of the Taiwan Smell Identification Test (TWSIT) in patients with CRSwNP undergoing endoscopic sinus surgery (ESS).

Methods: Patients with bilateral CRSwNP who underwent ESS were prospectively enrolled. The 22-item Sino-Nasal Outcome Test questionnaire and TWSIT were utilized to evaluate both subjective and objective olfactory function before surgery and 3 months postoperatively.

Results: Eighty-six patients with bilateral CRSwNP (53 males, 33 females) were enrolled. Moderate-to-high correlations were observed between the subjective smell loss scores and baseline TWSIT scores (r_s = 0.709 before treatment and r_s = 0.413 after treatment, both P < 0.001). The change in patient-reported smell loss was also significantly correlated with the change in TWSIT score (r_s = 0.675, P < 0.001). A TWSIT change of 6.5 points yielded a sensitivity of 71.6%, specificity of 91.7%, and an AUC of 0.789 (P < 0.001). Using the distribution-based method, the MCID was estimated as 7.4 (half the baseline standard deviation, SD) and 6.9 (half the delta SD). Based on both distribution- and anchor-based analyses, a TWSIT change of ≥ 7 points was determined to be the MCID.

Conclusion: This study established that a TWSIT score change ≥ 7 is clinically meaningful for patients with CRSwNP following sinus surgery. Bridging objective test results with subjective perceptions can help clinicians identify patients with suboptimal therapeutic outcomes and guide decisions regarding additional treatments.