Specific characteristics of exacerbation development in patients with different phenotypes of severe asthma

Aim: to assess specific characteristics of exacerbation development in patients with different phenotypes of severe asthma (SA) based on the analysis of the Russian Severe Asthma Registry of the Russian Respiratory Society. Patients and Methods: this retrospective study assessed the risk factors of asthma exacerbations, clinical signs, functional and laboratory test indicators recorded during disease exacerbations in 2060 patients with various SA phenotypes: allergic, non-allergic, associated with obesity, and asthma with fixed bronchial obstruction. The authors reviewed data of patient surveys and questionnaires, as well as medical documentation (patient physical examination, clinical history, results of laboratory and functional tests). Results: the largest group consisted of patients with non-allergic asthma phenotype. Their SA attacks were associated with inadequate background therapy and such aggressive factors as smoking and occupational hazards. Patients with non-allergic SA held the second position as regards the number of frequent exacerbation (more than three per year) and ranked first in terms of the number of patients receiving inadequate background therapy. The highest rate of exacerbations was observed in patients with allergic phenotype of the disease. This group included the fewest number of patients. Sensitization and failure to control SA were the major causes of disease exacerbations in these patients. The number of smokers and patients with comorbidities were the lowest in this group. The biggest risk of fatal exacerbations was reported in obese patients which is attributed to a very high comorbidity index. Patients with "obese" SA were the oldest ones. The disease onset occurred in these persons later than in other groups, and they had a long history of smoking. Half of patients in this group had more than three exacerbations yearly, and the increasing dyspnea was a specific characteristic of exacerbations. Patients suffering from SA with fixed obstruction phenotype had the lowest indicators of obstruction and its reversibility. Besides, they most frequently needed "emergency" inhalers. Smoking and previous upper respiratory tract infections were associated with exacerbation rate. Conclusion: the awareness of the disease exacerbation risk factors and specific characteristics of its clinical course related to a certain SA phenotype will help to develop an individualized management plan for such patients and thus to improve their treatment. KEYWORDS: severe asthma, asthma exacerbations, risk factors of exacerbations, asthma phenotypes, allergic phenotype, non-allergic phenotype, phenotype associated with obesity, phenotype with fixed bronchial obstruction. FOR CITATION: Kravchenko N.Yu., Molostova T.N., Belevsky A.S. et al. Specific characteristics of exacerbation development in patients with different phenotypes of severe asthma. Russian Medical Inquiry. 2023;7(2):96–102 (in Russ.). DOI: 10.32364/2587-6821-2023-7-2-96-102.