Misdiagnosis Among Frequent Exacerbators of Clinically Diagnosed Asthma and COPD in Absence of Confirmation of Airflow Obstruction.

PURPOSE: Clinical diagnosis of severe asthma and chronic obstructive lung disease (COPD) remains a challenge and often flawed with lack of objective confirmation of airflow obstruction (AO). Misdiagnosis of asthma and COPD has been reported in stable disease, data are non-existent in frequent exacerbators. We investigated misdiagnosis and its predictors in frequent exacerbators.
METHODS: The cohort comprised of frequent severe exacerbators (requiring ≥2 emergency room (ER) visits or hospitalizations) of physician diagnosed (PD)-asthma and PD-COPD. All patients underwent a rigorous diagnostic algorithm over a follow-up period of 10 ± 6 months. Two board-certified pulmonologists ascertained final diagnosis. Patients with persistent absence of AO were identified to have misdiagnosis. Multivariate logistic regression analyses were used to identify predictors of misdiagnoses.
RESULTS: Among 333 frequent exacerbators analyzed (171 patients with PD-asthma, 162 with PD-COPD, mean annual exacerbations 3.4 ± 2.8), 24 % of patients had a baseline post-bronchodilator spirometry. Misdiagnosis was found in 26 % (87 of 333) of patients. Another 12 % (41 of 333) of patients had obstructive lung diseases other than asthma and COPD. Independent risk factors for misdiagnosis were spirometry underutilization (PD-asthma: OR = 2.8, 95 % CI 1.16-6.78, p = 0.02 and PD-COPD: OR = 10.7, 95 % CI 2.05-56.27, p = 0.005) and pack years of smoking (PD-COPD: OR = 1.05, 95 % CI 1.01-1.11, p = 0.03).
CONCLUSIONS: Objective confirmation of AO is essential in preventing misdiagnosis in frequent severe exacerbators of clinically diagnosed asthma and COPD, a third of whom have neither. Spirometry utilization is strongly associated with a reduced risk of misdiagnosis. Smoking is associated with increased risk of misdiagnosis in severe COPD, but not asthma.