Published Online: August 1, 2014
Adverse asthma outcomes—such as hospitalization and death—are largely preventable yet continue to afflict some children. Notably, these outcomes afflict some minority children at higher rates than white children. However, differences in asthma prevalence between race/ethnic groups could influence interpretation of these asthma outcome disparities. Calculating asthma outcome rates using the entire population of children in a race/ethnic group as the denominator—population based rates (PBRs)—provides an overall measure of asthma impact for each group. However, because asthma prevalence varies between race/ethnic groups, PBRs may not provide specific information about the risks of poor outcomes for those with asthma in each group. Use of at-risk outcome rates (ARRs), which measure outcomes among those with asthma, removes the contribution of underlying prevalence differences between groups from the outcome rates. Analyzing ARRs in addition to PBRs may offer additional insight into racial disparities in asthma outcomes.
In an article recently published in The Journal of Allergy and Clinical Immunology, Akinbami and colleagues analyzed recent trends in asthma prevalence and asthma outcomes (asthma attack prevalence, health care use, and mortality) among black and white children 0-17 years of age. This study analyzed data from 2001 to 2010, supplied by the National Center for Health Statistics (NCHS).
The authors compare trends in disparities calculated using PBRs of asthma outcomes to those using ARRs. Asthma attack prevalence was estimated as the percentage of children with at least one asthma attack in the past 12 months based on questions in the National Health Interview Survey (NHIS), a household interview of a sample of the non-institutionalized civilian US population; asthma-related Emergency Department (ED) visits were estimated from observations with diagnoses of asthma in the National Hospital Ambulatory Medical Care Survey (NHAMCS), a national sample of ED visits; asthma-related hospitalizations were estimated from observations with asthma diagnoses in the National Hospital Discharge Survey (NHDS), a sample of discharges from hospitals; and asthma-related deaths were enumerated using the National Vital Statistics System (NVSS). PBRs were calculated by dividing the number of outcome events (ED visits from NHAMCS, hospitalizations from NHDS, and asthma-related deaths from NVSS) by US population estimates obtained from the US Census for children 0-17 years for the specified racial group. PBRs for asthma attack prevalence estimates were calculated using a denominator based on the NHIS survey. ARRs were calculated by dividing the number of persons or events by the estimated number of children with current asthma obtained from NHIS. Trends in both PBRs and ARRs for each racial group were analyzed for the years 2001 to 2010.
The authors found that disparities in asthma prevalence between black and white children increased from 2001 to 2010; at the end of this period, black children were twice as likely as white children to have asthma. Population-based rates (PBRs) showed that disparities in asthma outcomes remained stable (ED visits and hospitalizations) or increased (asthma attack prevalence, deaths). In contrast, analysis with at-risk rates (ARRs) which account for differences in asthma prevalence showed that disparities in asthma outcomes either remained stable (deaths), decreased (ED visits, hospitalizations), or did not exist (asthma attack prevalence).
These findings suggest that using at-risk rates to assess racial disparities in asthma outcomes, which accounts for prevalence differences between black and white children, adds another perspective to the population-based examination of asthma disparities. They explain that an at-risk rate analysis shows that among children with asthma, there is no disparity for asthma attack prevalence, and that progress has been made in decreasing disparities in asthma ED visit and hospitalization rates.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.