Prevalence and Characteristics of Undiagnosed COPD in Adults 40 Years and Older - Reports from the Tunisian Population-Based Burden of Obstructive Lung Disease Study

This study aimed to investigate the underdiagnosis of COPD and its determinants based on the Tunisian Burden of Obstructive Lung Disease study. We collected information on respiratory history symptoms and risk factors for COPD. Post-bronchodilator (Post-BD) FEV1/FVC < the lower limit of normal (LLN) was used to define COPD. Undiagnosed COPD was considered when participants had post-BD FEV1/FVC < LLN but were not given a diagnosis of emphysema, chronic bronchitis or COPD. 730 adults aged > 40 years selected from the general population were interviewed, 661 completed spirometry, 35 (5.3%) had COPD and 28 (80%) were undiagnosed with the highest prevalence in women (100%). When compared with patients with an established COPD diagnosis, undiagnosed subjects had a lower education level, milder airway obstruction (Post-BD FEV(1)z-score -2.2 vs. -3.7,p < 0.001), fewer occurrence of wheezing (42.9% vs. 100%,p = 0.009), less previous lung function test (3.6% vs. 42.8%,p = 0.019) and less visits to the physician (32.1% vs. 85.7%,p = 0.020) in the past year. Multivaried analysis showed that the probability of COPD underdiagnosis was higher in subjects who had mild to moderate COPD and in those who did not visit a clinician and did not perform a spirometry in the last year. Collectively, our results highlight the need to improve the diagnosis of COPD in Tunisia. Wider use of spirometry should reduce the incidence of undiagnosed COPD. Spirometry should also predominately be performed not only in elderly male smokers but also in younger women in whom the prevalence of underdiagnosis is the highest.