Objectives: Various minimal clinically important difference (MCID) threshold estimation techniques have been applied to seasonal allergic rhinitis (SAR). The objectives of this study are to (i) assess the difference in magnitude of alternative SAR MCID threshold estimates and (ii) evaluate the impact of alternative MCID estimates on health technology assessment (HTA).
Methods: Data describing change from baseline of the reflective Total Nasal Symptom Score (rTNSS) for four intranasal SAR treatments were obtained from United States Food and Drug Administration-approved prescribing information. Treatment effects were then compared with anchor-based MCID thresholds derived by Barnes et al. and thresholds obtained from an Agency for Healthcare Research and Quality (AHRQ) panel.
Results: The change in rTNSS score from baseline, represented as the average of the twice-daily recorded scores of the rTNSS, was -2.1 (p < .001) for azelastine hydrochloride 0.10%, 1.35 (p = .014) for ciclesonide, and -1.47 (p < .001) for fluticasone furoate. The change in the rTNSS score from baseline, represented by sum of the AM and PM score, was -2.7 for MP-AzeFlu (p < .001). The rTNSS change from baseline for each product was compared with anchor-based MCID threshold and the AHRQ panel estimates. Comparison of the observed treatment effect to the anchor-based and AHRQ panel MCID thresholds results in different conclusions, with clinically important differences being inferred when anchor-based estimates serve as the reference point.
Conclusion: The AHRQ panel MCID threshold for the rTNSS was twelve times larger than the anchor-based estimates resulting in conflicting recommendations on whether different SAR treatments provide clinically meaningful benefit.
Keywords: Intranasal combination; Intranasal corticosteroid; Outcome assessment; Seasonal allergic rhinitis; Treatment outcome.