Asthma

Understand

Overview

Asthma is a chronic inflammatory disease of the airways, in the course of which bronchial hyperresponsiveness develops — an excessive, exaggerated constrictive reaction of the bronchial smooth muscle to stimuli that produce no reaction, or a negligible one, in a healthy person. The typical clinical picture includes recurring episodes of wheezing, breathlessness, chest tightness, and coughing, which vary over time in severity and frequency, often worsen at night or in the early morning, and are triggered by physical exertion, viral infections, allergens, smoke, or cold air. Underlying these symptoms is variable airflow limitation through the airways which, unlike in chronic obstructive pulmonary disease, is substantially reversible, either spontaneously or with treatment.

Asthma is one of the most common chronic diseases worldwide, affecting, according to Global Initiative for Asthma (GINA) estimates, several hundred million people of all ages, though advances in medicine and treatment mean that well-controlled patients experience only minimal limitation of daily functioning. In adults, the disease may be a continuation of childhood-diagnosed asthma, but it just as often appears for the first time in adulthood — so-called late-onset asthma — which tends to be more often associated with obesity, chronic inflammation, occupational exposure (occupational asthma), or coexisting rhinitis and sinusitis, and less often with classic atopy.

Several phenotypes of asthma are distinguished, differing in their dominant inflammatory mechanism and typical treatment response: allergic (eosinophilic, IgE-dependent) asthma, usually of early onset and linked to atopic dermatitis or allergic rhinitis; non-allergic asthma, often of later onset, triggered by infections or exertion; obesity-associated asthma; and rarer neutrophil-predominant asthma, usually harder to control with standard treatment. Distinguishing the phenotype has practical clinical significance, because newer biologic drugs target specific inflammatory pathways and work best in an appropriately phenotype-matched patient.

Diagnosis of asthma is based on combining a characteristic clinical picture with objective confirmation of variable airflow limitation, most often via spirometry with a bronchodilator reversibility test (improvement in FEV1 after bronchodilators) — a test we discuss in more depth in our separate entry on spirometry. In some patients, bronchial hyperresponsiveness testing, home peak expiratory flow (PEF) monitoring, or exhaled nitric oxide (FeNO) measurement as a marker of eosinophilic inflammation are also useful. Asthma is sometimes overdiagnosed based on symptoms alone without objective functional confirmation, leading both to unnecessary treatment of people without the disease and to symptoms actually caused by asthma being misattributed to other conditions (e.g., vocal cord dysfunction or heart failure).

The contemporary approach to asthma treatment, reflected in GINA guidelines, has shifted significantly in recent years toward anti-inflammatory treatment used from the lowest severity steps onward, moving away from the model in which patients with mild asthma used only an as-needed bronchodilator (SABA) without any anti-inflammatory treatment. The SYGMA trials, conducted in more than 4,000 patients with mild asthma, showed that as-needed use of an inhaled corticosteroid combined with formoterol significantly reduced the risk of severe exacerbations compared with an as-needed bronchodilator alone, which directly influenced current treatment recommendations.

It's worth distinguishing well-controlled asthma from severe, treatment-resistant asthma — in the vast majority of patients, appropriately chosen inhaled treatment achieves full symptom control and normal life activity, while in a small percentage of patients, despite maximal standard therapy, the disease remains poorly controlled and requires in-depth phenotype diagnostics and consideration of biologic treatment. A common, potentially reversible cause of seemingly 'difficult' asthma is incorrect inhaler technique or poor adherence to chronic medication, so before escalating treatment, it's worth verifying these basic elements.

Asthma remains a chronic disease requiring regular medical care, even during symptom-free periods — stopping anti-inflammatory treatment once symptoms resolve is a common mistake that leads to a recurrence of inflammation and increased risk of a severe exacerbation. Establishing an individual treatment plan with a doctor, regularly assessing disease control, and, when needed, adjusting therapy based on objective lung function tests rather than subjective wellbeing alone, are essential.