Daily Dose: Global Disparities in Asthma Prevalence

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Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

Last week, we reported on findings from a study published in the Journal of Asthma and Allergy that examined the global burden of asthma and its impact on specific subgroups.

The study

Researchers conducted a targeted literature review for studies reporting asthma and subgroup prevalence and compared the results to country-specific qualities like economic status and air quality. Data were extracted from the Global Burden of Disease, Injuries, and Risk Factors Study 2019 and a literature review through PubMed in October 2021.

Asthma prevalence values were obtained from 69 countries, based on estimates from 405 sources from epidemiological reports and scientific literature. The targeted literature review included 9 studies with prevalence estimates for the different subgroups, with additional sources included where available per country/disease category. The literature included real-world evidence studies, along with some reviews, to form the base of the pearl-growing technique to find additional sources of the same level of relevance and authority.

Additionally, a qualitative analysis was conducted to include country-specific factors affecting global prevalence distributions. Asthma prevalence values were aggregated according to 2020 Air Quality Index (AQI) values, 2022 World Bank economic status, and 2017 Institute for Health Metrics and Evaluation Healthcare Access and Quality (HAQ) values.

Findings

A total of 162 publications were included in the study, with asthma prevalence values ranging across continents from 3.44% (Asia), 3.67% (Africa), 4.90% (South America), 5.69% (Europe), 8.29% (North America), to 8.33% (Oceana).

The global asthma prevalence according to subgroups included:

• Severe asthma, 26.7%

• Eosinophilic asthma, 0.99%

• Asthma with allergic rhinitis, 48.95%

• Nasal polyps, 7% to 25.4%

Furthermore, countries with higher air quality, income status, and health care access and quality reported a higher asthma prevalence. For instance, the United States had the highest asthma prevalence (11.25%) and had good AQI (9.6), while Bangladesh reported the lowest asthma prevalence (1.43%) and had poor AQI (77.1). The researchers explained these results may be attributed to fine-scale geographical variations in air quality that are not captured by AQI, as well as the presence of household pollution that is extremely common in many countries.

Authors' comment

"Asthma prevalence values were low in LMICs, potentially indicating health system deficiencies resulting in low diagnosis and reporting. The prevalence of eosinophilic asthma and severe asthma phenotypes was high in many countries, although the prevalence estimates of all asthma subgroups were quite variable."

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