By Dr Yash Goyal

 There are approximately 300 million people with asthma worldwide including America, a latest research paper in the International journal “Lancet” reports. Despite a current plateau, the burden of this disease is likely to increase due to population growth, urbanisation, and ageing. Disease onset is associated with low birth weight, preterm birth, viral infections, in-utero passive smoke exposure, urbanisation, and occupational exposures. 

      It is disclosed in a joint research paper, July 15 issue, titled “Asthma: epidemiology, risk factors, and opportunities for prevention and treatment”  by Asthma specialists across Europe, Asia (including India covering Jaipur), Africa, America, Middle East, and Oceania. Author cum researchers’ panel comprises Shamathi M Jayasooriya, Graham Devereux, Prof Joan B Soriano, Nishta Singh (Jaipur in India), Prof Refiloe Masekela, Prof Kevin Mortimer, and Prof Peter Burney. This is the second in a Series of four papers about the global epidemiology of chronic respiratory disease. 

       Asthma is characterised by variable airflow obstruction and is associated with symptoms of cough, wheeze, and dyspnoea, and with airway inflammation and hyper-responsiveness.

       Asthma prevalence (unadjusted for age) varies by country, ranging from 1% to 18%, with particularly high rates in the USA, the UK, and Portugal. In contrast, mortality rates from asthma are the highest in Nepal, India, Bangladesh, Myanmar, and Indonesia. Although mortality rates in sub-Saharan Africa are lower than in south and southeast Asia, they remain high relative to the region’s low prevalence rates. Differences in the within-country asthma prevalence distribution are even greater than the differences between countries.

      Obesity is associated with increased incidence and severity of asthma, whereas exposure to small allergen particles leads to severe disease. In adults and adolescents, inhaled corticosteroids in combination with formoterol (as anti-inflammatory reliever or as maintenance and anti-inflammatory reliever therapy) are widely recommended to control the symptoms of asthma.

  For children, low-dose inhaled corticosteroid is the preferred first-line treatment. Monotherapy with short-acting β-agonists is strongly discouraged.  The WHO Global Action Plan for the Prevention and Control of Non-communicable Diseases includes availability of affordable combination inhalers for asthma. Co-ordinated national asthma policies, ensuring access to inhalers, have resulted in fewer hospitalisations and school and work absences. Future asthma prevalence could be reduced by good maternal and infant care, with reduction in premature births and reduction in infant respiratory infections, and by reduction in obesity at all ages.

America

 The US Centers for Disease Control and Prevention reports that more than 27 million people in the USA have asthma.24 Although this figure has remained stable over the last decade, great statal and county disparities exist among different ethnic groups. African Americans and Hispanic populations have higher rates of asthma and asthma-related mortality compared with non-Hispanic white Americans. In Latin America, both in adults and children, a high burden of symptoms and use of health services have been identified by GAN and ISAAC, with prevalences of asthma ranging from 5% to 15% in different countries; Chile, Argentina, Cuba, and Costa Rica report some of the highest prevalence rates of the condition in the region. Socioeconomic disparities, urbanisation, and environmental pollution contribute to the high burden of asthma from Mexico to the tip of South America. Additionally, less than ideal access to health care and medications exacerbates the effect of asthma on quality of life and increases health-care costs.

Asia 

Asia presents a diverse picture of asthma prevalence. In countries such as Japan and South Korea, asthma prevalence is relatively low, at about 2–5%. In contrast, urban areas of China and India report very high prevalence rates, particularly among children. According to Nishtha Singh CeO of JAIPUR’s Asthma Bhawan, in India, between ISAAC (International Study of Asthma and Allergies in Childhood)  phase 3 and GAN (Global Asthma Network) phase 1, there was a substantial decrease in the prevalence of current wheeze among both children and adolescents between 2009 and 2022. Of people with current wheeze, 75–82% remained clinically undiagnosed. Among individuals with current wheeze who had no diagnosis, less than 1% took a daily inhaled corticosteroid. In people with current wheeze who were clinically diagnosed with asthma, use of daily inhaled corticosteroid increased to 2–8% in different age groups. 

        In South-East Asia, mortality rates have been consistently high at about 13 in 100 000 per year; this high rate might reflect low access to inhaled corticosteroids in some areas. Late Onset of Asthma arises due to increasing multimorbidity and people often developing multiple age-related conditions, the differential for breathlessness often broadens in later life. 

       Globally, approximately one in ten children and one in 20 adults have asthma. Between one in eight and one in ten adults and children have rhinoconjunctivitis or eczema. Approximately 300 million people worldwide have asthma—a burden that is expected to increase in the 21st century due to population growth, increased urbanisation, and ageing of the population.