A Novel Scoring System to Distinguish Vocal Cord Dysfunction From Asthma

BACKGROUND: Vocal cord dysfunction is often misdiagnosed and mistreated as asthma, which can lead to increased and unnecessary medication use and increased health care utilization. OBJECTIVE: To develop a valid scoring index that could help distinguish vocal cord dysfunction from asthma. METHODS: We compared the demographics, comorbidities, clinical symptoms, and symptom triggers of subjects with vocal cord dysfunction (n =89) and those with asthma (n=59). By using multivariable logistic regression, we identified distinguishing features associated with vocal cord dysfunction, which were weighted and used to generate a novel score. The scoring index also was tested in an independent sample with documented vocal cord dysfunction (n=72). RESULTS: We identified symptoms of throat tightness and dysphonia, the absence of wheezing, and the presence of odors as a symptom trigger as key features of vocal cord dysfunction that distinguish it from asthma. We developed a weighted index based on these characteristics, the Pittsburgh Vocal Cord Dysfunction Index. By using a cutoff of >= 4, this index had good sensitivity (0.83) and specificity (0.95) for the diagnosis of vocal cord dysfunction. The scoring index also performed reasonably well in the independent convenience sample with laryngoscopy-proven vocal cord dysfunction and accurately made the diagnosis in 77.8% of subjects. CONCLUSION: The Pittsburgh Vocal Cord Dysfunction Index is proposed as a simple, valid, and easy-to-use tool for diagnosing vocal cord dysfunction. If confirmed by a prospective evaluation in broader use, it may have significant clinical utility by facilitating a timely and accurate diagnosis of vocal cord dysfunction, thereby preventing misdiagnosis and mistreatment as asthma. Future prospective validation studies will need to be performed. (C) 2013 American Academy of Allergy, Asthma & Immunology