Bronchial asthma as a non-communicable disease

The health of the individuals is diversely affected by many non-communicable diseases (NCDs) across the globe. NCDs include chronic respiratory diseases, cardiovascular diseases, diabetes mellitus, and cancer. The Global Asthma Network (GAN) has recently published the Global Asthma Report (GAR) for 2022, highlighting the significant impact of asthma as one of the most prevalent non-communicable diseases (NCDs) worldwide.¹

Asthma is encountered worldwide affecting all age groups, and it causes substantial disability and deaths worldwide. The Global Initiative for Asthma (GINA) has defined asthma as ‘a heterogeneous disease usually characterized by chronic airway inflammation. It presents with a history of respiratory symptoms such as shortness of breath, wheeze, chest tightness, and cough that vary overtime and in intensity together with variable expiratory airflow limitation.’²

For a long period of time, asthma has been believed to be a single disease. In 2018, a Lancet Commission suggested a range of new ways of thinking about asthma, its mechanisms, and its treatment, challenging conventional concepts of asthma as a single disease. The Commission considered asthma as an umbrella term, describing it as a clinical syndrome, and proposed the need for a more targeted approach.³

Asthma includes a heterogeneous group of patients and attempts have been made to find a common denominator among situations such as chronic inflammation of the airways, allergy, and psychogenic factors. But the unique common denominator has been shown to be hyperreactive airways which manifest with variable airway constriction in response to a wide variety of endogenous and exogenous stimuli.⁴

Airway hyper-reactivity is manifested by the propensity for widespread but reversible narrowing of the airways in response to diverse inciting factors. It is associated with constriction of airways, and smooth muscle, inflammation and mucosal oedema, accumulation of mucus, and an influx of inflammatory cells including eosinophils and neutrophils. The heterogeneity of asthma includes precipitating factors, location of airway obstruction, degree of reversibility, onset, frequency, grade of severity, periodicity, and duration of attack, symptomatology and response to therapy.⁵

The precipitating factors responsible for an attack of asthma may be extrinsic, intrinsic, or mixed. Airway obstruction can occur either in the small airways, large airways, or in both simultaneously. The degree of reversibility in the airway obstruction can vary, ranging from complete reversal with either a short or long duration to incomplete reversal. The onset of the attack may be sudden or insidious. The severity of the attack may be graded as mild and infrequent, frequent and episodic, or chronic with mild, moderate, or marked severity. The periodicity of attacks may be seasonal or perennial. The attacks may occur as nocturnal asthma, morning dipping, or labile asthma. The duration of the attack may be short or long. The symptoms are characterized by breathlessness, cough, or both. The attack may respond to bronchodilators, anti-inflammatory agents, or both.

From a clinical angle, asthma is categorized into extrinsic asthma, intrinsic asthma, occupational asthma, childhood asthma, exercise-induced asthma, reflux-triggered asthma, nocturnal asthma, allergic bronchopulmonary aspergillosis, carcinoid syndrome, and allergic angiitis and granulomatosis. These various clinical categories of asthma suggest the need for a classification of asthma as a syndrome rather than a single disease entity. Asthma is a collection of signs centered on the airways on which diverse trigger factors act to bring about airway hyperactivity and reversible airways obstruction.⁵

The Global Asthma Report 2022 has stressed the necessity to manage asthma as a chronic disease rather than a series of acute episodes or asthma attacks.¹ Asthma is essentially managed by the use of relievers such as short-acting β2-agonists (SABA) that relax the airway smooth muscle leading to reversal of airway narrowing and corticosteroids which reduce the underlying airway inflammation. The inhaled route of drug administration is often preferred for managing respiratory conditions as it effectively controls symptoms and manifestations. Inhaled corticosteroids (ICS) are highly effective in this regard, and the addition of long-acting β2-agonists (LABA) further enhances their therapeutic effects.⁶

The two main components of airway obstruction, bronchospasm and inflammation, require treatment with bronchodilators and anti-inflammatory agents. The aim of the treatment is to achieve and maintain normal airway function. Preventing exposure to allergens is an effective strategy for reducing inflammation. Airborne allergens such as pollens, molds, dust mites, and pet dander are known triggers of allergic inflammation and should be avoided to prevent allergic reactions.