Validation of the dyspnea index in adolescents with exercise-induced paradoxical vocal fold motion.JAMA Otolaryngol Head Neck Surg. 2014 Sep; 140(9):823-8.JO
Paradoxical vocal fold motion (PVFM) affects almost 1 million adolescents in the United States. However, to date, no disease-specific objective measure exists to assess symptom severity and response to treatment in adolescents with exercise-induced PVFM.
To validate the Dyspnea Index (DI) quality-of-life instrument (previously validated for adults with breathing disorders) in children aged 12 to 18 years with exercise-induced PVFM and to determine the minimum significant DI change corresponding to patient-reported or caregiver-reported improvement or worsening of symptoms.
DESIGN, SETTING, AND PARTICIPANTS
A longitudinal study of 56 patients (age range, 12-18 years) diagnosed as having exercise-induced PVFM and their caregivers from February 1, 2013, to September 30, 2013, in an outpatient pediatric otolaryngology office practice.
The DI was administered to patients and caregivers, with items modified to reflect the perspective of caregivers.
MAIN OUTCOMES AND MEASURES
Appropriate DI change was measured to reflect improvement or worsening of symptoms. Test-retest reliability was accomplished by having a subset of patients and caregivers complete the instrument twice within 2 weeks before therapy. Internal consistency was assessed by calculation of Cronbach α. Discriminant validity and convergent validity were determined by comparing DIs with assessment of global change in symptoms.
The patient and caregiver mean (SD) DI changes were -12.9 (9.6) and -14.7 (9.3), respectively (P < .001 for both). Reliability was established by test-retest analysis with an intraclass correlation coefficient of 0.8 and by calculation of Cronbach α = 0.80, demonstrating internal consistency. Discriminant validity was determined by assessing for a significant DI change when patients globally perceived that a change existed after treatment (P < .001). A DI change of 8 or higher (P < .001) correlated with patient-reported significant change. Convergent validity was demonstrated by evaluating for significant DI change when no change was reported following treatment (P < .001).
CONCLUSIONS AND RELEVANCE
The DI appears to be a valid and reliable instrument to assess quality of life in exercise-induced pediatric PVFM. A DI change of 8 or higher seems significant. This instrument can serve as an objective tool to assess change in exercise-induced pediatric PVFM following speech therapy.