Modeling Recurrence in Idiopathic Subglottic Stenosis With Mobile Peak Expiratory Flow

Abstract

Objectives/Hypothesis: We sought to establish normative peak expiratory flow (PEF) data for patients with idiopathic subglottic stenosis (iSGS), evaluate whether immediate changes in PEF after a procedure predict long-term treatment response, and test if a decline in longitudinal PEF is associated with disease recurrence.Study Design: International, prospective, 3-year multicenter cohort study of 810 patients with untreated, newly diagnosed, or previously treated iSGS.Methods: iSGS patients consented and enrolled in the North American Airway Collaborative (NoAAC) iSGS 1000 cohort recorded PEF data on a mobile smartphone app. Cox regression tested the associations between the magnitude of postoperative PEF improvement and longitudinal 90-day PEF decline with the risk of disease recurrence.Results: Within the NoAAC iSGS 1000 cohort, 810 patients participated in a 3-year prospective study comparing surgical treatment efficacy and 385 had appropriate PEF measurements and follow-up data. Of those patients, 42% (161/385) required at least one operation during study follow-up. The mean PEF preceding operative intervention was 241 L/min (95% confidence interval [CI]: 120-380) corresponding to a predicted PEF of 52%. The mean increase in PEF following a procedure was 111 L/min (95% CI: 96-125 L/min). Interestingly, the magnitude of immediate PEF improvement was not predictive of disease recurrence (hazard ratio [HR] for 100 L/min increase = 0.90, 95% CI: 0.60-1.00). However, recurrence was associated with the magnitude of PEF decline over 90 days (30% vs. 10% decline, HR = 2.2, 95% CI: 1.5-3.0).Conclusions: We provide normative PEF data on a large iSGS patient cohort. The degree of PEF improvement immediately after surgery was not associated with a longer procedure-free interval. However, a 30% decline in PEF over 90 days was associated with elevated risk of disease recurrence.

Can the Remote Use of a Peak Flow Meter Predict Severity of Subglottic Stenosis and Surgical Timing?

“…18 Alternative strategies aim to leverage patient-reported outcomes to inform care. 2,8,11 PFMs are inexpensive, at home, user friendly devices. These data show that PFMs can be used to reliably monitor SGS disease progression and predict surgical timing.…”

“…In addition, frequent clinic visits and PFTs can be expensive and burdensome to both our healthcare system and to patients with SGS 18 . Alternative strategies aim to leverage patient‐reported outcomes to inform care 2,8,11 . PFMs are inexpensive, at home, user friendly devices.…”

“…PFMs are simple to use, at home devices that have previously been used to monitor asthma exacerbations 9,10 . Recent studies have begun to investigate the utility of PFMs as a tool to monitor disease progression in SGS 11 . PFM measurements are analogous to the PEF of PFTs 9 .…”

“…9,10 Recent studies have begun to investigate the utility of PFMs as a tool to monitor disease progression in SGS. 11 PFM measurements are analogous to the PEF of PFTs. 9 The objectives for this study were to 1) determine to what extent PEFR from PFTs correlates with PFM measurements in this patient population, 2) to compare the ability of PFM, PFT measurements, and DI scores to predict surgery timing, and to 3) track the change in PFM measurements over individual patients' disease course.…”

Impact of Serial Intralesional Steroid Injections on Idiopathic Subglottic Stenosis

“…PEF was used as a surrogate for disease severity, with values >200 L/min reflecting “less airway compromise” and values <200 L/min reflecting “more airway compromise”. The 200 L/min cutoff was used to approximate the average preoperative PEF in the iSGS 1000 cohort, 241 L/min, 19 with a more conservative value chosen to reflect clinically meaningful airway obstruction.…”