Severe asthma: Comparison of different classifications of severity and control.

Background: Criteria of asthma severity and control lack standardization.

Objective: to compare classifications of asthma severity and control, applied to patients from a severe asthma clinic.

Methods: Cross-sectional study of 473 patients followed up for ≥6 months, reclassified using three criteria: 1) the World Health Organization (WHO) 2010, 2) the American Thoracic Society (ATS) 2000, and 3) the European Respiratory Society (ERS)/ATS 2014. In order to evaluate disease control, the 2012 and 2014 Global Initiative for Asthma (GINA) classifications were compared.

Results: According to the definition of WHO 2010, 429 had Difficult-to-treat severe asthma and only 12 presented Treatment-resistant severe asthma. 114 patients had Refractory asthma by ATS 2000 and 88 had Severe asthma by ERS/ATS 2014. Considering the definitions of WHO 2010, only 9 out of 12 with Treatment-resistant and 64 out of 429 with Difficult-to-treat severe asthma met the criteria of ATS 2000 and ERS/ATS 2014. As for GINA classification of control, 208 (44%) of the 473 subjects were classified as having asthma controlled by the 2014 criteria, whereas only 45 (10%) patients had controlled asthma by the GINA 2012 criteria. The Kappa statistic indicates the highest agreement of the severity classification occurred between the criteria of ATS 2000 and ERS/ATS 2014 (0.64).

Conclusion: Good agreement was found between Refractory asthma ATS 2000 and Severe asthma ERS/ATS 2014 classifications. However, poor agreement was observed between the severity rating proposed by the WHO and other classifications. The GINA control classifications of 2012 and 2014 also agreed poorly.