title: Minimal Clinically Important Difference (MCID) in Allergic Rhinitis: Agency for Healthcare Research and Quality or Anchor-Based Thresholds?
abstract: In 2013, the Agency for Healthcare Research and Quality (AHRQ) recommended that allergic rhinitis (AR) studies calculate a minimal clinically important difference (MCID) based on an estimated threshold equal to 30% of the maximum total nasal symptom score. Applying this threshold, their data showed no differences between well-established treatments, and a subsequent analysis using prescribing information found no differences between active treatments and placebo controls.
  
  
  
  The objective of this study was to demonstrate the application of an evidence-based model to determine MCIDs for AR studies, with an absolute value for an anchor-based threshold and validated methods for calculating distribution-based thresholds.
  
  
  
  Using the same studies as the AHRQ report, anchor- and distribution-based MCID thresholds were determined for 3 clinical comparisons identified by the AHRQ: (1) oral antihistamine+intranasal corticosteroid (INCS) versus INCS, (2) montelukast versus INCS, and (3) intranasal antihistamine+INCS in a single device versus the monotherapies. The outcomes were compared with those reported using the AHRQ threshold.
  
  
  
  No treatment comparison met the AHRQ-defined MCID threshold; all treatments were determined to be equivalent for all 3 queries. In contrast, the evidence-based model revealed some differences between treatments: INCS > montelukast; intranasal antihistamine+INCS > either monotherapy. No clinically relevant benefit was observed for adding an oral antihistamine to INCS, but some studies were not optimal choices for quantitative determination of MCIDs. Updating the literature search revealed no additional studies that met the AHRQ inclusion criteria.
  
  
  
  The evidence-based threshold for MCID determination for AR studies should supersede the threshold recommended in the AHRQ report.
authors.affiliation: Division of Immunology and Allergy, Department of Pediatrics, University of California San Diego School of Medicine, San Diego, Calif; Allergy and Asthma Medical Group and Research Center, San Diego, Calif. Electronic address: eliomeltzer@gmail.com.
authors.forename: Eli O
authors.initials: EO
authors.lastname: Meltzer
authors.affiliation: Florida Center for Allergy and Asthma Control, Nova Southeastern University College of Health Professions, Fort Lauderdale, Fla.
authors.forename: Dana
authors.initials: D
authors.lastname: Wallace
authors.affiliation: Section of Allergy and Immunology, Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, Mo.
authors.forename: Mark
authors.initials: M
authors.lastname: Dykewicz
authors.affiliation: Shneyer Statistics LLC, Denville, NJ.
authors.forename: Lucy
authors.initials: L
authors.lastname: Shneyer
mesh_terms: D000085:Acetates / Q000627:therapeutic use; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D003521:Cyclopropanes; D019317:Evidence-Based Medicine; D006077:Government Agencies; D006633:Histamine Antagonists / Q000627:therapeutic use; D006801:Humans; D000071081:Minimal Clinically Important Difference; D011804:Quinolines / Q000627:therapeutic use; D065631:Rhinitis, Allergic / Q000188:drug therapy*; D013440:Sulfides; D014481:United States
chemical_list: D000085:Acetates; D000305:Adrenal Cortex Hormones; D003521:Cyclopropanes; D006633:Histamine Antagonists; D011804:Quinolines; D013440:Sulfides; C093875:montelukast
keywords: Allergic rhinitis; Intranasal antihistamine; Intranasal corticosteroid; Leukotriene receptor antagonist; Minimal clinically important difference (MCID); Oral antihistamine; Seasonal allergic rhinitis (SAR); Total nasal symptom score (TNSS)