**5. Asthma chronic non-reversible perennial**

Problems in the differential diagnosis of bronchial asthma not reversible and COPD are well known.

It is accepted that 30% of asthmatic patients are smokers, and this variant of overlap syndrome has been well described by various authors. There is evidence that smokers with asthma are more resistant to treatment. The natural history of patients with COPD asthmic syndrome involves a fast loss of FEV1; they have a decreased life expectancy, though this aspect is not well known because many studies included as non-smokers and former smokers.
