Fact checked byKristen Dowd

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April 17, 2023
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Rates of asthma with recurrent exacerbations in children vary by race, age, other factors

Fact checked byKristen Dowd
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Key takeaways:

  • The overall crude incidence rate for asthma with recurrent exacerbations was 6.07 per 1,000 person-years.
  • Rates were highest among children aged 2 to 4 years and among Hispanic and non-Hispanic Black children.

Incidence rates of asthma with recurrent exacerbations vary with time of surveillance, decade of birth, age, race, ethnicity and census region, according to a study published in The Journal of Allergy and Clinical Immunology.

Environmental exposures that affect these incidence rates may change as well, Rachel L. Miller, MD, chief of the division of clinical immunology, Icahn School of Medicine at Mount Sinai, and colleagues wrote.

girl using asthma inhaler
Geography, time, sex and parental history as well as age, race and ethnicity appear to influence the inception of asthma with recurrent exacerbations among pediatric patients. Image: Adobe Stock

“Some children are prone to asthma that is characterized by experiencing multiple exacerbations or flares,” Miller told Healio.

“Despite the substantial health care and family burden, the causal factors driving asthma with recurrent exacerbations (ARE) are not well-characterized. There is a lack of even basic descriptive epidemiological data,” she continued.

Rachel L. Miller

The study examined data from the Environmental Influences on Child Health Outcomes (ECHO) consortium, which demonstrated that multiple demographic factors were related to incidence rates of asthma in the United States.

These data also suggested that population subgroups have experienced different and substantial impacts from environmental exposures that have changed over time beyond any inherited risk.

Crude rates

The study focused on 734 children in the ECHO consortium born between 1990 and 2017 with ARE, defined as two reports or more of systemic corticosteroid use.

The median time between these exacerbations was 18.4 months (interquartile range [IQR], 11.76-34.99). Overall, the crude incidence rate (IR) of ARE was 6.07 per 1,000 person-years (95% CI, 5.63-6.51).

Crude rates of ARE increased from 2.06 (95% CI, 0-4.17) in the 1990s to 5.35 (95% CI, 4.34-6.35) in the 2000s. Also, children born between 1990 and 1999 had the lowest crude rates of ARE (IR = 4.18; 95% CI, 2.97-5.4).

Children aged 2 to 4 years experienced a peak in crude ARE rates at 18.55 (95% CI, 16.59-20.52) before rates diminished with age. The highest ARE rates were found among non-Hispanic Black (IR = 11.99; 95% CI, 10.59-13.4) and Hispanic Black (IR = 11.42; 95% CI, 5.81-17.03) children.

In fact, ARE rates among non-Hispanic Black children were almost three times higher than rates for non-Hispanic white children (IR = 4.1; 95% CI, 3.6-4.6). Similarly, rates for Hispanic Black children were almost three times higher than those of Hispanic white children (IR = 3.85; 95% CI, 2.69-5).

The crude rates in the Northeast (IR = 8.57; 95% CI, 7.32-9.82) were 3.8 times higher than those in the West (IR = 2.27; 95% CI, 1.8-2.74). Also, the 6.9 (95% CI, 6.26-7.55) crude rate for males was 1.3 times higher than the 5.14 (95% CI, 4.56-5.73) rate for females.

Children with a parental history of asthma had a crude rate of 11.82 (95% CI, 10.74-12.9), which was more than three times greater than the 3.69 (95% CI, 3.15-4.23) reported by children who did not have this history.

Demographic changes in the underlying ECHO population influenced the changes in crude rates between surveillance periods and birth decades, the researchers said, such as the substantially more children born between 2000 and 2009 reporting Black race.

Specific analyses

Between 1990 and 2022, ARE IRs decreased slightly among non-Hispanic white children but remained relatively stable among non-Hispanic and Hispanic Black children, the researchers said. Rates also remained consistently the highest for non-Hispanic and Hispanic Black children, the researchers continued.

In the Northeast, IRs peaked at 19.84 (95% CI, 2.45-37.23) during the 1990s before falling to 19.61 (95% CI, 14.83-24.83) in the 2000s and then to 5.9 (95% CI, 4.76-7.03) between 2010 and 2022.

Incidence rates rose from 1.67 (95% CI, 0-4.08) in the South and 3.2 (95% CI, 1.89-4.51) in the Midwest in the 2000s to 8.38 (95% CI, 7.16-9.61) in the South and 7.84 (95% CI, 6.7-8.98) in the Midwest between 2010 and 2022.

Across all three decades of surveillance, children with a parental history of asthma had higher IRs than those who did not have such a history.

Compared with the 1990s, ARE rates among non-Hispanic white and Black children aged 2 to 4 years increased for those born during the 2000s and then decreased for those born between 2010 and 2017.

Incidence rates for children aged 5 to 9 years declined with successive birth decades for non-Hispanic white and Black children. ARE rates for those aged 10 to 19 years decreased for non-Hispanic white children over the birth decades but increased for non-Hispanic Black children.

Non-Hispanic white children aged 10 to 19 years had the highest ARE rates among children born in the 1990s. Non-Hispanic Black children had higher rates in every age group for all other decades. Compared with children who identified as white or other ethnicities born between 2000 and 2009, non-Hispanic and Hispanic Black children had higher rates as well.

In all age groups, non-Hispanic and Hispanic Black children had the highest ARE rates, with the highest rates among non-Hispanic Black children (IR = 52.33; 95% CI, 42.7-61.97) and Hispanic Black children (IR = 26.89; 95% CI, 6.96-46.82) aged 2 to 4 years.

Additional IRs included 20.89 (95% CI, 18.04-23.74) for boys aged 2 to 4 years and 5.66 (95% CI, 4.79-6.52) for boys aged 5 to 9 years, which were 1.3 times higher than those for girls aged 2 to 4 years (IR = 15.84; 95% CI, 13.18-18.5) and girls aged 5 to 9 years (IR = 4.09; 95% CI, 3.33-4.85).

Across all races and ethnic groups, the researchers continued, ARE rates were 1.3 to 2.1 times higher among boys compared with girls. Also, ARE rates increased by a factor of 1.6 to 7.8 for children with a parental history of asthma across race and ethnicity categories.

Overall, ARE rates were three times higher for children with a parental history of asthma compared with those without such a history, across all three age groups reviewed, with approximately threefold increases for both boys and girls.

Conclusions, next steps

“Young children, ages 2 to 4 years, especially those with parental history of asthma, suffered the highest rates of asthma with recurrent exacerbations. Also important was time of surveillance, decade of birth, race and ethnicity, and census region,” Miller said.

“These all suggest substantial impacts of environmental exposures that may change over time in the etiology of ARE,” she continued. “These do not occur independent of parental history of asthma.”

Considering the increase in IRs from the 1990s to the 2000s followed by the decrease in rates, the researchers said that shifting environmental and/or socio-behavioral exposures may be contributing risk factors, in addition to disproportionate access to optimal asthma care.

With the highest ARE rates among preschool children, including IRs of more than 15 cases per person-years in adjusted analyses, and decreases among those aged 10 to 19 years, the researchers further said environmental exposures may be more common or damaging in this age group.

Further, the researchers said multilevel socioeconomic and environmental exposures that may operate prenatally through maternal exposures that influence child development or impact access to optimal treatment for preventing exacerbations likely mediate the racial and ethnic differences that they observed.

“Describing the incidence rates of ARE across various pediatric populations is a critical first step for identifying and being alerted to potential risk factors and causes,” Miller said.

By better understanding the risk factors behind ARE, the researchers said, better preventive strategies to improve short-term morbidity and long-term respiratory outcomes may be developed.

“New studies could examine key elements of the early environment that could contribute, including viral respiratory tract infections, indoor allergens, environmental tobacco smoke, air pollution, stress, socioeconomic status and where children live,” Miller said.

For more information:

Rachel L. Miller, MD, FAAAAI, can be reached at rachel.miller2@mssm.edu.