Asthma: Diagnosis and Management ____________________________________________________________
DEFINITION Since 1958, several attempts have been made to establish a consensus definition of asthma but thus far have been unsuccessful, and ongoing research continues to evolve the definition. The Global Initiative for Asthma (GINA) defines asthma as a “heterogenous disease, usually characterized by chronic airway inflammation” [8]. It is defined by a history of respiratory symptoms, such as wheeze, shortness of breath, chest tightness, and cough, that vary over time and in intensity, together with variable expiratory airflow limitation [8]. This definition comprises elements set forth by other organizations, including the National Asthma Education Prevention Program (NAEPP), that does not recognize asthma as a specific disease with a single cause, but instead is categorized as a “syndrome composed of multiple phenotypes” [9]. Asthma is considered a chronic, albeit reversible, respiratory disorder. This inflammatory condition produces hyper-reactive and hyper-responsive airway and lungs, causing episodic, revers- ible airway obstruction through bronchospasms, increased mucus secretions, and mucosal edema. The hyper-reactive lungs of a patient with asthma are more sensitive than most individuals’ and may become inflamed or edematous when exposed to specific irritants (e.g., cold air, animal dander, dust, tobacco smoke, care exhaust fumes, grass) or by the respira- tory involvement of viral infections, exercise, or laughter . The immune system of an individual with asthma will over-react to these irritants, constricting the airways and filling them with mucus; constricted airways interfere with the movement of air in and out of the lungs, making breathing difficult [8; 9]. Asthma is marked by recurrent episodes of wheezing, breath- lessness, chest tightness, and/or coughing. Usually, these periods are associated with widespread but variable airflow obstruction followed by a period of relief, either spontaneously or in response to treatment. Asthma has many puzzling aspects, and its symptoms may wax and wane, especially seasonally. Unlike other respiratory diseases, such as congestive obstruc- tive pulmonary disease (COPD) and emphysema, in which air trapping and hyperinflation of the lungs also occur, asthma is reversible with the use of proper medications and therapies. Long-term lung tissue damage can occur when asthma attacks occur frequently or when the disorder is poorly controlled. Permanent damage would require many instances of severe attacks. In children, whose lungs are still developing, the risk of long-term damage is greater [8; 9].
EPIDEMIOLOGY
GLOBAL IMPACT As noted, approximately 262 million people worldwide are living with asthma. In 2019, there were approximately 461,000 deaths attributed to asthma [3; 15]. The incidence and severity of the condition varies globally. Although for many years asthma was characterized as a condi- tion limited to industrialized countries, it is now recognized as a significant health issue in developing countries as well. More than 40 million people in Central and South America and more than 50 million people in Africa have asthma. More than 80% of asthma deaths occur in developing countries [3; 16]. The 2019 Lancet Global Burden of Disease report indicates that countries on the lower and middle parts of the sociodemographic index spectrum sustain the greatest number of asthma deaths, while prevalence of asthma is greatest in countries higher on the sociodemographic index spectrum [15]. Disability-adjusted life-year rates are very high on most of the African continent, as well as in-and-around the Indian subcontinent, southeast Asia, and parts of the United States. NATIONAL STATISTICS The global increase in asthma incidence and its impact on public health are also evidenced in the United States. From 2019 to 2022, it was estimated that 8% of Americans had asthma [1; 2]. The number of individuals diagnosed with asthma increased at a rate of 1.5% per year between 2001 and 2010, to a prevalence of 8.4% in 2010, and have remained nearly the same since, with 8% in 2013 and 7.8% in 2019 [1; 2]. Historically, rates of asthma have decreased with age; however, data from 2023 show the prevalence of asthma at 6.7% in children and at 8.9% in adults [1; 17; 18]. The cause of the proliferation of asthma within the last few decades is not yet known, although some have attributed the rise to environmental factors and expansion of the condition’s diagnostic criteria. The National Health Interview Survey ques- tions, from which most of the statistics on asthma prevalence are obtained, changed slightly after 1997, causing a shift in how the condition and associated statistics were reported. In 2001, the Centers for Disease Control and Prevention (CDC) introduced a more precise measurement of asthma. Since then, the trend has remained stable at historically high levels [17; 18].
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