Lara J. Akinbami

Status of Childhood Asthma in the United States, 1980–2007

Centers for Disease Control and Prevention data were used to describe 1980–2007 trends among children 0 to 17 years of age and recent patterns according to gender, race, and age. Asthma period prevalence increased by 4.6% per year from 1980 to 1996. New measures introduced in 1997 show a plateau at historically high levels; 9.1% of US children (6.7 million) currently had asthma in 2007. Ambulatory care visit rates fluctuated during the 1990s, whereas emergency department visits and hospitalization rates decreased slightly. Asthma-related death rates increased through the middle 1990s but decreased after 1999. Recent data showed higher prevalence among older children (11–17 years), but the highest rates of asthma-related health care use were among the youngest children (0–4 years). After controlling for racial differences in prevalence, disparities in adverse outcomes remained; among children with asthma, non-Hispanic black children had greater risks for emergency department visits and death, compared with non-Hispanic white children. For hospitalizations, for which Hispanic ethnicity data were not available, black children had greater risk than white children. However, nonemergency ambulatory care use was lower for non-Hispanic black children. Although the large increases in childhood asthma prevalence have abated, the burden remains large. Potentially avoidable adverse outcomes and racial disparities continue to present challenges. These findings suggest the need for sustained asthma prevention and control efforts for children.

Heterogeneity of childhood asthma among hispanic children : Puerto rican children bear a disproportionate burden

OBJECTIVES. To estimate differences in asthma prevalence among Hispanic subgroups and non-Hispanic children living in the United States and to explore the association between these differences and risk factors. METHODS. Weighted logistic regression analyses of merged 1997 to 2001 National Health Interview Survey data were used to estimate the prevalence of asthma diagnosis and asthma attacks in a sample of 46511 children (age: 2–17 years) living in the 50 states and the District of Columbia. RESULTS. Puerto Rican children had the highest prevalence of lifetime asthma (26%) and recent asthma attacks (12%), compared with non-Hispanic black children (16% and 7%, respectively), non-Hispanic white children (13% and 6%, respectively), and Mexican children (10% and 4%, respectively). Adjustment for asthma risk factors did not change these comparisons appreciably. Compared with non-Hispanic white children, the adjusted odds ratios (ORs) for a lifetime asthma diagnosis were 2.33 (95% confidence interval [CI]: 1.90–2.84) for Puerto Rican children, 1.16 (95% CI: 1.04–1.29) for non-Hispanic black children, and 0.90 (95% CI: 0.79–1.03) for Mexican children. Birthplace influenced the association between ethnicity and lifetime asthma diagnosis differently for Puerto Rican and Mexican children. Compared with United States-born non-Hispanic white children with United States-born parents, the adjusted ORs were 1.95 (95% CI: 1.48–2.57) for Puerto Rican children in families with the child and parent(s) born in the 50 states/District of Columbia and 2.50 (95% CI: 1.51–4.13) for island-born Puerto Rican children with island-born parents. The corresponding adjusted ORs for Mexican children were 1.05 (95% CI: 0.90–1.22) for families born in the 50 states/District of Columbia and 0.43 (95% CI: 0.29–0.64) for those born in Mexico. The results were similar for recent asthma attacks. CONCLUSIONS. The appreciably higher asthma morbidity rates experienced by Puerto Rican children cannot be explained by sociodemographic and other risk factors measured in the National Health Interview Survey. The heterogeneity of asthma among Hispanic subgroups should be considered in developing effective public health prevention and intervention strategies.

Racial and Income Disparities in Childhood Asthma in the United States

OBJECTIVE To examine racial and income disparities in asthma prevalence in US children, and disparities in morbidity and ambulatory health care use among children with asthma. METHODS Using 1993-1996 National Health Interview Survey data, we measured asthma prevalence and morbidity in children aged 3 to 17 years (N = 14 211) stratifying by race and poverty status. Measures of morbidity included asthma-related activity limitation and number of bed days. We used the ratio of asthma-related doctor contacts to number of bed days in the past 2 weeks to measure health care use adjusted for severity of illness. RESULTS An annual average of 7.4% of children aged 3 to 17 years had asthma. There were no significant differences in asthma prevalence between race and poverty groups. In contrast, asthma-related morbidity was higher among black and poor children. Black poor children were most likely to have activity limitations due to asthma: 49% were limited compared with about 20% of black nonpoor, white poor, and white nonpoor children. Among children with activity limitations, black children and white poor children were more likely to have severe limitations, and white nonpoor children were least likely. Finally, white nonpoor children had the highest level of ambulatory care use for asthma after accounting for disease severity, and black poor children had the lowest level. CONCLUSIONS We found no significant racial or income disparities in asthma prevalence among children in the United States. However, black children and poor children are at higher risk for activity limitation, more severe activity limitation, and relative underuse of ambulatory health care. Black children living in poverty are at highest risk. Targeted interventions to reduce the burden of asthma morbidity in this population are likely to reduce disparities in asthma morbidity as well as reduce overall childhood asthma morbidity.

Childhood overweight prevalence in the United States: the impact of parent-reported height and weight.

Parent‐reported height and weight are often used to estimate BMI and overweight status among children. The quality of parent‐reported data has not been compared to measured data on a national scale for all race/ethnic groups in the United States. Parent‐reported height and weight for 2–17‐year‐old children in two national health interview surveys—the 1999–2004 National Health Interview Survey (NHIS) and the 2003–2004 National Survey of Childrens Health (NSCH)—were compared to measured values from a national examination survey—the 1999–2004 National Health and Nutrition Examination Survey (NHANES). Compared to measured data, parent‐reported data overestimated childhood overweight in both interview surveys. For example, overweight prevalence among 2–17‐year‐olds was 25% (s.e. 0.2) using parent‐reported NHIS data vs. 16% (s.e. 0.6) using measured NHANES data. Parent‐reported data overestimated overweight among younger children, but underestimated overweight among older children. The discrepancy between reported and measured estimates arose mainly from reported height among very young children. For children aged 2–11 years, the mean reported height from NHIS was 3–6 cm less than mean measured height from NHANES (P < 0.001) vs. no difference among children aged 16–17 years. Measured data remains the gold standard for surveillance of childhood overweight. Although this analysis compared mean values from survey populations rather than parent‐reported and measured data for individuals, the results from nationally representative data reinforce previous recommendations based on small samples that parent‐reported data should not be used to estimate overweight prevalence among preschool and elementary school–aged children.

Racial and Ethnic Differences in Asthma Diagnosis Among Children Who Wheeze

Background. Racial and ethnic disparities exist in reported childhood asthma prevalence, but it is unclear if disparities stem from true prevalence differences or a different likelihood of receiving a diagnosis from a health professional. Concern has been raised that asthma may be underdiagnosed, particularly among minority children who have more restricted access to high-quality health care. Objective. To examine racial/ethnic differences among currently symptomatic children in acquiring an asthma diagnosis to determine if relative underdiagnosis among minorities exists. Children for whom no symptoms were reported (a group that includes those with well-controlled symptoms) were excluded from the analysis. Methods. The 1999 National Health Interview Survey includes a nationally representative sample of children with reported wheezing symptoms. We included children 3 to 17 years old in the study and analyzed racial/ethnic differences in asthma diagnosis, controlling for young age, gender, parental education, single-parent household, central-city residence, region of residence, health insurance, having a usual place of care, and parent-reported severity of wheezing symptoms. Results. Among those reported to have wheezed in the past year (n = 946), 83% of Puerto Rican, 71% of non-Hispanic black, and 65% of Mexican children were diagnosed with asthma compared with 57% of non-Hispanic white children. Using non-Hispanic white children as the reference group, the approximate adjusted relative risk for physician diagnosis of asthma given wheezing in the past year was 1.43 (95% confidence interval [CI]: 1.04, 1.63) for Puerto Rican, 1.22 (95% CI: 1.03, 1.37) for non-Hispanic black, and 1.19 (95% CI: 0.94, 1.39) for Mexican children. Minority children were reported to have greater severity of wheezing symptoms. Even after accounting for this increased severity, children in racial and ethnic minority groups were as or more likely to have a reported asthma diagnosis than non-Hispanic white children. Conclusions. Our findings do not provide evidence for the hypothesis that symptomatic minority children are underdiagnosed with asthma compared with non-Hispanic white children. To the contrary, among currently symptomatic children, minority children were more likely to be diagnosed than non-Hispanic white children even after accounting for the higher wheezing severity among minority children.

Changing Trends in Asthma Prevalence Among Children

BACKGROUND: Childhood asthma prevalence doubled from 1980 to 1995 and then increased more slowly from 2001 to 2010. During this second period, racial disparities increased. More recent trends remain to be described. METHODS: We analyzed current asthma prevalence using 2001–2013 National Health Interview Survey data for children ages 0 to 17 years. Logistic regression with quadratic terms was used to test for nonlinear patterns in trends. Differences between demographic subgroups were further assessed with multivariate models controlling for gender, age, poverty status, race/ethnicity, urbanicity, and geographic region. RESULTS: Overall, childhood asthma prevalence increased from 2001 to 2009 followed by a plateau then a decline in 2013. From 2001 to 2013, multivariate logistic regression showed no change in prevalence among non-Hispanic white and Puerto Rican children and those in the Northeast and West; increasing prevalence among 10- to 17-year-olds, poor children, and those living in the South; increasing then plateauing prevalence among 5- to 9-year-olds, near-poor children, and non-Hispanic black children; and increasing then decreasing prevalence among 0- to 4-year-olds, nonpoor, and Mexican children and those in the Midwest. Non-Hispanic black-white disparities stopped increasing, and Puerto Rican children remained with the highest prevalence. CONCLUSIONS: Current asthma prevalence ceased to increase among children in recent years and the non-Hispanic black-white disparity stopped increasing due mainly to plateauing prevalence among non-Hispanic black children.

The association between childhood asthma prevalence and monitored air pollutants in metropolitan areas, United States, 2001―2004

BACKGROUND Air pollution exposure has been linked to adverse respiratory health outcomes among children, primarily in studies of acute exposures that are often in limited geographic areas. We sought to assess the association between chronic outdoor air pollution exposure, as measured by 12-month averages by county, and asthma among children in metropolitan areas across the nation. METHODS Eligible children included those aged 3-17 years residing in US metropolitan areas who were sampled in the 2001-2004 National Health Interview Survey (N=34,073). 12-month average air pollutant levels for sulfur dioxide, nitrogen dioxide, ozone and particulate matter were compiled by county for 2000-2004. Eligible children were linked to pollutant levels for the previous 12 months for their county of residence. Adjusted odds ratios of having current asthma or an asthma attack in the past 12 months were estimated in single pollutant logistic regression models. RESULTS Children in counties with ozone and, to a less consistent degree, particulate matter levels in the highest quartile were more likely to have current asthma and/or a recent asthma attack than children residing in counties with the lowest pollution levels; the adjusted odds for current asthma for the highest quartile of estimated ozone exposure was 1.56 (95% confidence interval [CI]: 1.15, 2.10) and for recent asthma attack 1.38 (95% CI: 0.99, 1.91). No associations were found with sulfur dioxide or nitrogen dioxide levels. CONCLUSION Although the current US standard for ozone is based on short-term exposure, this cross-sectional study suggests that chronic (12-month) exposure to ozone and particles is related to asthma outcomes among children in metropolitan areas throughout the US.

Asthma outcomes: Healthcare utilization and costs

BACKGROUND Measures of healthcare utilization and indirect impact of asthma morbidity are used to assess clinical interventions and estimate cost. OBJECTIVE National Institutes of Health institutes and other federal agencies convened an expert group to propose standardized measurement, collection, analysis, and reporting of healthcare utilization and cost outcomes in future asthma studies. METHODS We used comprehensive literature reviews and expert opinion to compile a list of asthma healthcare utilization outcomes that we classified as core (required in future studies), supplemental (used according to study aims and standardized), and emerging (requiring validation and standardization). We also have identified methodology to assign cost to these outcomes. This work was discussed at an National Institutes of Health-organized workshop in March 2010 and finalized in September 2011. RESULTS We identified 3 ways to promote comparability across clinical trials for measures of healthcare utilization, resource use, and cost: (1) specify the study perspective (patient, clinician, payer, and society); (2) standardize the measurement period (ideally 12 months); and (3) use standard units to measure healthcare utilization and other asthma-related events. CONCLUSIONS Large clinical trials and observational studies should collect and report detailed information on healthcare utilization, intervention resources, and indirect impact of asthma, so that costs can be calculated and cost-effectiveness analyses can be conducted across several studies. Additional research is needed to develop standard, validated survey instruments for collection of provider-reported and participant-reported data regarding asthma-related health care.

Air Pollution and Childhood Respiratory Allergies in the United States

Background Childhood respiratory allergies, which contribute to missed school days and other activity limitations, have increased in recent years, possibly due to environmental factors. Objective In this study we examined whether air pollutants are associated with childhood respiratory allergies in the United States. Methods For the approximately 70,000 children from the 1999–2005 National Health Interview Survey eligible for this study, we assigned between 40,000 and 60,000 ambient pollution monitoring data from the U.S. Environmental Protection Agency, depending on the pollutant. We used monitors within 20 miles of the child’s residential block group. We used logistic regression models, fit with methods for complex surveys, to examine the associations between the reporting of respiratory allergy or hay fever and annual average exposure to particulate matter ≤ 2.5 μm in diameter (PM2.5), PM ≤ 10 μm in diameter, sulfur dioxide, and nitrogen dioxide and summer exposure to ozone, controlling for demographic and geographic factors. Results Increased respiratory allergy/hay fever was associated with increased summer O3 levels [adjusted odds ratio (AOR) per 10 ppb = 1.20; 95% confidence interval (CI), 1.15–1.26] and increased PM2.5 (AOR per 10 μg/m3 = 1.23; 95% CI, 1.10–1.38). These associations persisted after stratification by urban–rural status, inclusion of multiple pollutants, and definition of exposures by differing exposure radii. No associations between the other pollutants and the reporting respiratory allergy/hay fever were apparent. Conclusions These results provide evidence of adverse health for children living in areas with chronic exposure to higher levels of O3 and PM2.5 compared with children with lower exposures.

US Prevalence and Trends in Tobacco Smoke Exposure Among Children and Adolescents With Asthma

OBJECTIVE: To examine exposure to tobacco smoke products (TSPs), environmental tobacco smoke (ETS), and in-home smoke among youth with asthma in the United States. METHODS: Nationally representative, cross-sectional data from 2250 youth aged 4 to 19 years with current asthma in the 1988–1994, 1999–2004, and 2005–2010 National Health and Nutrition Examination Survey (NHANES) were analyzed. Outcomes were use of TSPs (serum cotinine level >10 ng/mL or self-reported recent use of cigarettes, cigars, or pipes) and, among non-TSP users, ETS exposure (serum cotinine ≥0.05 ng/mL) and in-home smoke exposure (reported). Multiple logistic regression analyses assessed the associations between the outcomes and age, gender, race/ethnicity, and family income. RESULTS: Among adolescents (aged 12–19 years) with asthma in 2005–2010, 17.3% reported TSP use. Among youth (aged 4–19 years) with asthma who did not use TSPs, 53.2% were exposed to ETS and 17.6% had in-home smoke exposure. Among low-income youth, 70.1% and 28.1% had exposure to ETS and in-home smoke, respectively. After controlling for sociodemographic factors, higher prevalence of exposure to ETS and in-home smoke persisted among low-income youth. Between 1988–1994 and 2005–2010, there was a decline in ETS and in-home smoke exposure (both P < .001). CONCLUSIONS: ETS exposure among youth with asthma declined between 1988–1994 and 2005–2010, but a majority remained exposed in 2005–2010, with higher exposure among low-income youth. More than 1 in 6 youth with asthma in 2005–2010 were exposed to in-home smoke and a similar portion of adolescents used TSPs.