Physiology-based minimum clinically important difference thresholds in adult laryngotracheal stenosis

S. Mahmoud Nouraei, Ramon A. Franco, Jayme R. Dowdall, S. A.Reza Nouraei, Heide Mills, Jag S. Virk, Guri S. Sandhu, Mike Polkey

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Objectives/Hypothesis: Delivering evidence-based patient care is predicated on the availability of objective and validated outcome measures. We aimed to calculate physiology-based minimum clinically important difference (MCID) values for adult laryngotracheal stenosis (LTS). Study Design: Prospective observational study. Methods: Patient demographics, morbidities, and stenosis severity were assessed preoperatively. Flow-volume loops and Medical Research Council (MRC) dyspnea grades were measured in 21 males and 44 females before and 6 to 8 weeks after airway surgery, and before treating recurrent disease in 10 patients. Anchor and distribution-based methodologies were used to calculate MCIDs for treatment efficacy and disease recurrence respectively. Results: The mean age at treatment was 46 ± 16 years. The most common etiology was idiopathic subglottic stenosis (38%). Most lesions (66%) obstructed >70% of the lumen. There were strong correlations between treatment-related changes in total peak flow (TPF) (ΔTPF) (peak expiratory flow + |peak inspiratory flow|) and the ratio of area under the flow-volume loop (AUC) to forced vital capacity (FVC) (ΔAUCTotal/FVC), and treatment-related changes in the MRC grade (ΔMRC) (r = -0.76 and r = -0.82, respectively). Both TPF and AUCTotal/FVC discriminated between effective (ΔMRC <0) and ineffective (ΔMRC ≥0) interventions, yielding MCID values of 4.2 L/s for TPF and 2.1 L2/s for AUCTotal/FVC, respectively. Ten patients required airway treatment for recurrent disease, and TPF and AUCTotal/FVC levels had distribution-based MCID values of 0.9 and 0.6, respectively. Conclusions: Flow-volume loops provide a quantitative method of objectively assessing outcomes in LTS. TPF is the most convenient index for this purpose, but AUCTotal/FVC provides marginally greater sensitivity and specificity.

Original languageEnglish (US)
Pages (from-to)2313-2320
Number of pages8
Issue number10
StatePublished - Oct 1 2014
Externally publishedYes


  • Evidence-based medicine
  • Flow-volume loops
  • Laryngotracheal stenosis
  • Minimum clinically important difference
  • Outcome measures
  • Pulmonary function test

ASJC Scopus subject areas

  • Otorhinolaryngology


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