Fixed airflow obstruction in patients with asthma

Abstract

According to international guidelines in recent years, it has been proposed that bronchial asthma (BA) with fixed airflow obstructions (FAO) be identified as a separate phenotype.The aimof the study was the clinical and functional characterization and identification of risk factors for the formation of the phenotype BA with FAO.Materials.We examined adult outpatients with BA (n = 432) and a combination of BA and chronic obstructive pulmonary disease (COPD) without exacerbation (n = 58). Anamnesis collection, objective examination, spirometry with the assessment of obstruction reversibility (spirograph 2120 Vitalograph, UK), atopic status assessment (skin samples or specific IgE in serum) were performed. The level of eosinophils and neutrophils in peripheral blood was determined (by the impedance method on the automatic haemoanalyzer). Nitric oxide of exhaled air was measured by a chemiluminescent gas analyzer (Logan 4100, UK). BA control and quality of life of patients were evaluated using the Russian language versions of the Asthma Control Questionnaire (ACQ-5) and the St. George's Hospital Respiratory Questionnaire (St. George's Respiratory Questionnaire – SGRQ) respectively. Statistical analysis was carried out using parametric and non-parametric methods using the application program package Statistica 10. The value of bilateral p < 0.05 was considered statistically significant.Results.Among patients with BA without COPD, the incidence of FAO was 31%, with the most frequent (60%) FAO was found in severe BA and less often – in the mild (7%) and medium (36%) course of the disease. Among patients with a combination of BA and COPD, a severe course of the disease prevailed – 77%. Patients with FAO were older and had a longer duration of disease. The presence of FAO was accompanied by lower rates of pulmonary function, a higher frequency of positive markers of eosinophilic inflammation, worse indicators of control over BA and quality of life, a higher need for “emergency” drugs and drugs to support the treatment of BA, including biological therapy, increased use of healthcare resources. The risk factors for FAO in patients with BA include the debut of BA under 25 years of age (odds ratio (OR) – 1.6), sensitization to ticks of house dust (OR – 1.8), passive smoking (OR – 6.5), suffered during the life of pneumonia (OR - 3.0).Conclusion. The combination of BA + FAO can be considered as a separate phenotype of the disease with a more severe course and less favorable prognosis.