A novel scoring system to distinguish vocal cord dysfunction from asthma

Abstract

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.

Keywords: ANOVA; Analysis of variance; Asthma; BMI; Body mass index; CI; Clinical scoring index; Confidence interval; GERD; Gastroesophageal reflux; IBS; IQR; Interquartile range; Irritable bowel syndrome; N/A; NPV; Negative predictive value; Not available; OR; Odds ratio; PPV; Positive predictive value; SOB; Shortness of breath; VCD; Vocal cord dysfunction.