Pulmonary Function Tests May Better Predict Dyspnea-Severity in Patients with Subglottic Stenosis Compared to Clinician-Reported Stenosis

Abstract

Objective: Patients with subglottic stenosis (SGS) present with varied degree of breathing complaints. The dyspnea index (DI) is a 10-question patient-reported outcome measure designed to measure the severity of upper airway obstruction. We set out to determine whether pulmonary function tests or clinician-reported degree of stenosis best predicted DI scores. Methods: Thirty patients with SGS were retrospectively reviewed over a 6-year period. One visit from each patient was included. Data including peak expiratory flow rate (PEFR), body-mass index (BMI), clinician-reported degree of stenosis, and DI scores were reviewed. Multiple linear regression was performed to determine how degree of stenosis and PEFR % predicted the variation in DI score. Results: PEFR % better predicted DI scores compared to degree of stenosis (partial correlation −0.32 vs 0.17). After stepwise elimination, PEFR % remained in the regression and was significantly associated with DI scores ( F[1, 29] = 9.38, P = .005). BMI did not demonstrate a linear relationship with DI scores and was not included in the regression ( r = −.02). The PEFR % unstandardized coefficient was −0.25 (95% CI: −0.42 to −0.08, P = .005). The model predicts that a 4% increase in the PEFR % results in a 1-point decrease in the DI score (95% CI: −1.68 to −0.32). Conclusion: This study suggests that pulmonary function tests may be a better in-office measure to substantiate the severity of symptoms in patients with SGS.

Decision‐Making in the Treatment of Idiopathic Subglottic Stenosis: A Survey of Laryngologists

“…3 Bhatt et al showed PEF was a more reliable indicator of a patient's symptoms compared to the clinician's subjective assessment of stenotic degree via tracheoscopy or laryngoscopy. 7 Despite their proven usefulness, the survey showed that less than half of laryngologists routinely use PFTs in caring for patients with iSGS. Although the survey did not specifically inquire about the reasons for not performing PFTs routinely, it is likely that factors such as limited clinic time or lack of equipment contribute to this.…”

“…Carpenter et al demonstrated peak expiratory flow (PEF) as a clinically efficient and reliable way to monitor the progression of iSGS and predict surgical intervention 3 . Bhatt et al showed PEF was a more reliable indicator of a patient's symptoms compared to the clinician's subjective assessment of stenotic degree via tracheoscopy or laryngoscopy 7 . Despite their proven usefulness, the survey showed that less than half of laryngologists routinely use PFTs in caring for patients with iSGS.…”

“…6). Eighteen participants indicated the interval between surgical treatment and the first injection to be on the same day ( 6), 1 month (7), and more than 1 month (5).…”

“…Recently, pulmonary function tests (PFTs) as a diagnostic tool have shown to be reliable and efficient with some surgical predictive value. [3][4][5][6][7] Endoscopic dilation (ED) is the mainstay treatment for iSGS but has a high recurrence rate within 3 years. 1,8,9 Recurrent dilations and the negative impact on patients' quality of life suggest investigation for a more effective adjuvant procedure.…”

“…These methods involve using local laryngeal anesthesia and passing a scope beneath the vocal folds to examine the subglottic region. Recently, pulmonary function tests (PFTs) as a diagnostic tool have shown to be reliable and efficient with some surgical predictive value 3–7 …”