Public health interventions for asthma: an umbrella review, 1990-2010

Visualizing the knowledge domains and research trends of childhood asthma: A scientometric analysis with CiteSpace

BACKGROUND

Asthma is one of the most common chronic diseases in children globally. In recent decades, advances have been made in understanding the mechanism, diagnosis, treatment and management for childhood asthma, but few studies have explored its knowledge structure and future interests comprehensively.

OBJECTIVE

This scientometric study aims to understand the research status and emerging trends of childhood asthma.

METHODS

CiteSpace (version 5.8.R3) was used to demonstrate national and institutional collaborations in childhood asthma, analyze research subjects and journal distribution, review research keywords and their clusters, as well as detect research bursts.

RESULTS

A total of 14,340 publications related to childhood asthma were extracted from Web of Science (core database) during January 2011 to December 2021. The results showed that academic activities of childhood asthma had increased steadily in the last decade. Most of the research was conducted by developed countries while China, as a developing country, was also actively engaged in this field. In addition to subjects of allergy and immunology, both public health aspects and ecological environmental impacts on the disease were emphasized recently in this research field. Keywords clustering analysis indicated that research on asthma management and atopy was constantly updated and became the two major research focuses recently, as a significant shift in research hotspots from etiology and diagnosis to atopic march and asthma management was identified. Subgroup analysis for childhood asthma management and atopy suggested that caregiver- or physician-based education and interventions were emerging directions for asthma management, and that asthma should be carefully studied in the context of atopy, together with other allergic diseases.

CONCLUSIONS

This study presented a comprehensive and systematic overview of the research status of childhood asthma, provided clues to future research directions, and highlighted two significant research trends of asthma management and atopy in this field.

Assessment of a University-Based Outpatient Asthma Education Program for Children

INTRODUCTION

To assess the effect of a pediatric asthma intervention program on reducing asthma morbidity.

METHODS

Study eligibility criteria included aged less than 18 years and at least two office visits for asthma in the previous year. Patients were randomly assigned to either the control or intent to intervene group. The intervention included home visits and education on the basic pathophysiology of asthma, self-management techniques, modification of asthma triggers, and proper use of asthma medications by a certified nurse educator.

RESULTS

Using simple randomization, 901 eligible pediatric patients with asthma were assigned; 458 to the control and 443 to the intent to intervene group. Of the 443 patients randomized to the intent to intervene group, 271 received the asthma education intervention. Most of the remaining 172 patients in the intent to intervene group did not receive the intervention owing to not having an appointment during the study period. Only 27 families allowed a home visit. After controlling for the difference in sex, children in the intent to intervene group had significantly less total clinic visits (incidence rate ratio [IRR] = 0.53, p < .01), and steroid bursts (IRR = 0.47, p < .01) than controls.

DISCUSSION

The implementation of a pediatric asthma education program decreased both the total clinic visits and the need for steroid bursts consistent with better asthma control. We demonstrated the benefit of a dedicated asthma educator in university-based community practice and recommend this intervention be considered a standard of care for children with asthma in all health-care settings.

Return on investment of self-management education and home visits for children with asthma

OBJECTIVE

Priorities of the Centers for Disease Control and Prevention's 6|18 Initiative include outpatient asthma self-management education (ASME) and home-based asthma visits (home visit) as interventions for children with poorly-controlled asthma. ASME and home visit intervention programs are currently not widely available. This project was to assess the economic sustainability of these programs for state asthma control programs reimbursed by Medicaid.

METHODS

We used a simulation model based on parameters from the literature and Medicaid claims, controlling for regression to the mean. We modeled scenarios under various selection criteria based on healthcare utilization and age to forecast the return on investment (ROI) using data from New York. The resulting tool is available in Excel or Python.

RESULTS

Our model projected health improvement and cost savings for all simulated interventions. Compared against home visits alone, the simulated ASME alone intervention had a higher ROI for all healthcare utilization and age scenarios. Savings were primarily highest in simulated program participants who had two or more asthma-related emergency department visits or one inpatient visit compared to those participants who had one or more asthma-related emergency department visits. Segmenting the selection criteria by age did not significantly change the results.

CONCLUSIONS

This model forecasts reduced healthcare costs and improved health outcomes as a result of ASME and home visits for children with high urgent healthcare utilization (more than two emergency department visits or one inpatient hospitalization) for asthma. Utilizing specific selection criteria, state based asthma control programs can improve health and reduce healthcare costs.

Worldwide asthma epidemiology: insights from the Global Health Data Exchange database

BACKGROUND

Enhanced focus on primary care provision is essential for lowering the risk of asthma exacerbation and complications, as well as for decreasing asthma-related hospitalizations and deaths. This article provides an update on current worldwide epidemiology of asthma.

METHODS

Worldwide epidemiologic information on asthma was obtained through electronic searches in the Global Health Data Exchange (GHDx) database.

RESULTS

In 2017, the incidence of asthma was 43.12 million new cases/year (0.56%), while in that same year, prevalence and mortality accounted for 272.68 million cases (3.57%) and 0.49 million deaths (0.006%), respectively. Although the number of asthma cases significantly increased during the last 25 years, disability-adjusted life years (DALYs) and deaths constantly declined. After adjustment of asthma incidence, prevalence, and DALYs for worldwide demographic variation, no significant changes could be seen during the last 25 years, while asthma mortality significantly declined during the same period. Asthma incidence peaks before the age of 5 years, whereas prevalence and DALYs peaks are observed between 0 and 14 years. DALYs also display a second peak, between 45 and 74 years. Asthma mortality increases with aging, reaching the peak after 80 years. The epidemiologic burden and mortality of asthma are constantly higher in women than in men. An inverse, highly significant correlation can be found between sociodemographic index and asthma incidence (r = -0.98) or mortality (r = -0.96).

CONCLUSION

Although the worldwide burden of asthma remains high, incidence and prevalence are not apparently translating into an escalating clinical and economic burden in terms of health loss and deaths.

Using a human-centered design approach for collaborative decision-making in pediatric asthma care

OBJECTIVES

Human-centered design (HCD) is a qualitative methodology that empathizes with end-users and assists in formulating preferable and practical interventions. We explored the utility of HCD in improving pediatric asthma healthcare outcomes among patient and caregiver populations within an urban academic center.

STUDY DESIGN

HCD employs a multiphase process that aims to identify the needs of end users and reframe solutions around each stakeholder's preference patterns.

METHODS

Ethnographic-style observations were initiated among pediatric asthma healthcare providers, community environmental activists, local government public health officials, households with a young child (<12 years of age) with asthma, and adolescent asthmatics. Common themes from the observations served as the basis for understanding users' experiences and determining actionable areas of improvement within outpatient asthma care. Multistakeholder brainstorming sessions led to the emergence of three prototypes that underwent low-fidelity field testing.

RESULTS

The first prototype elucidated caregivers' preferred outpatient asthma support systems using a newly created visual decision-making aid. The second constructed prototype was a child-oriented asthma activity sheet that allowed children to better communicate their understanding and impact of asthma care. The final prototype attempted to improve interactions between providers, caregivers, and children/adolescents using visual prompts to enhance empathetic and clinically-relevant dialogue.

CONCLUSION

Engaging a diverse population of relevant stakeholders in disease processes that use design thinking yield relevant solutions with enhanced community buy-in. The prototypes are continuing to undergo iterative field testing in local community and academic asthma care sites.

Housing code violation density associated with emergency department and hospital use by children with asthma

Local agencies that enforce housing policies can partner with the health care system to target pediatric asthma care. These agencies retain data that can be used to pinpoint potential clusters of high asthma morbidity. We sought to assess whether the density of housing code violations in census tracts-the in-tract asthma-relevant violations (such as the presence of mold or cockroaches) divided by the number of housing units-was associated with population-level asthma morbidity and could be used to predict a hospitalized patient's risk of subsequent morbidity. We found that increased density in housing code violations was associated with population-level morbidity independent of poverty, and that the density explained 22 percent of the variation in rates of asthma-related emergency department visits and hospitalizations. Children who had been hospitalized for asthma had 1.84 greater odds of a revisit to the emergency department or a rehospitalization within twelve months if they lived in the highest quartile of housing code violation tracts, compared to those living in the lowest quartile. Integrating housing and health data could highlight at-risk areas and patients for targeted interventions.

Allergen sensitization profiles in a population-based cohort of children hospitalized for asthma

RATIONALE

Allergen sensitization is associated with asthma morbidity. A better understanding of allergen sensitization patterns among children hospitalized for asthma could help clinicians tailor care more effectively. To our knowledge, however, sensitization profiles among children hospitalized for asthma are unknown.

OBJECTIVES

We sought to describe allergen sensitization profiles and the distribution of self-reported in-home exposures among children hospitalized for asthma. We also sought to assess how sensitization profiles varied by sociodemographic and clinical factors.

METHODS

This population-based cohort study includes data for 478 children, aged 4-16 years, hospitalized for an asthma exacerbation. Predictors included child age, race, sex, insurance status, reported income, salivary cotinine, exposure to traffic-related air pollution, asthma and atopic history, and season of admission. Outcomes included serum IgE specific to Alternaria alternata/A. tenuis, Aspergillus fumigatus, American cockroach, mouse epithelium, dust mite (Dermatophagoides pteronyssinus and farinae), cat dander, and dog dander (deemed sensitive if IgE ≥ 0.35). Self-reported adverse exposures included mold/mildew, water leaks, cockroaches, rodents, and cracks or holes in the walls or ceiling. Presence of carpeting and furry pets was also assessed.

MEASUREMENTS AND MAIN RESULTS

More than 50% of included patients were sensitized to each of Alternaria, Aspergillus, dust mite, cat dander, and dog dander; 28% were sensitized to cockroach and 18% to mouse. Roughly 68% were sensitized to three or more allergens with evidence of clustering. African American children, compared with white children, were more likely to be sensitized to Alternaria, Aspergillus, cockroach, and dust mite (all P<0.01). White children were more likely to be sensitized to mouse, cat, and dog (all P<0.01). Lower income was associated with cockroach sensitization whereas higher income was associated with dog and cat sensitization (all P<0.01). Atopic history was associated with sensitization to three or more allergens (P<0.01). Although 42% reported exposure to at least one adverse in-home exposure (and 72% to carpet, 51% to furry pets), only weak relationships were seen between reported exposures and sensitizations.

CONCLUSIONS

Most children admitted to the hospital for asthma exacerbations are sensitized to multiple indoor allergens. Atopy on the inpatient unit serves as a potential target for improvement in chronic asthma management.

Population Health Considerations for Pediatric Asthma: Findings from the 2011-2012 California Health Interview Survey

Childhood asthma is a prevalent and costly chronic condition. Optimal management enables secondary and tertiary prevention. The goal was to identify population health considerations for pediatric asthma in California to inform the development of quality improvement interventions. California Health Interview Survey 2011-2012 is a random-digit dial telephone survey conducted in 5 languages. It includes 44,000 households from all 58 counties in California. This study assessed factors related to symptom control and health care use in children ages 2-11 years with asthma. An estimated 492,385 (9.6%) of children in California currently have asthma. Urban and rural residents face comparable asthma disease burdens. School-age male children as well as Asian and African American children are disproportionately affected. Asthma causes significant morbidity, with poorer health status, high utilization of emergency care, and the need for daily medication use. Only 38% of children with asthma have a recent asthma management plan. Half of all children with asthma did not receive influenza immunization in the past year, although this reflects the overall low rate of influenza vaccination. Parents of children with asthma frequently utilize the Internet for health information and communication with their child's health care provider. Children with asthma in California face several population-level challenges, including poor health status, low influenza vaccination rates, high use of emergency care, and suboptimal use of health literacy tools. Focusing on improved care coordination and preventive care for high-risk groups is especially urgent given the expansion of public health insurance and impending shortages in the primary care workforce. (Population Health Management 2016;19:145-151).

The added effect of comorbidity on health-related quality of life in patients with asthma

PURPOSE

To examine the effect of comorbidities on health-related quality of life (HRQoL) and their interaction with asthma control.

METHODS

In a random sample of adults with asthma, we measured generic (EQ5D) and disease-specific (AQ5D) utility scores. Asthma symptom control was determined using the 2014 Global Initiative for Asthma Management Strategy. Comorbidity scores were calculated using a validated questionnaire. We used two-part regression models to measure the adjusted difference in utility across levels of symptom control and comorbidity scores and to examine the relative role of symptom control and comorbidity in explaining the variation in HRQoL.

RESULTS

A total of 2,299 observations from 460 adult patients (mean age 52 years, 67 % women) were included. Compared to controlled asthma, uncontrolled asthma was associated with -0.018 reduction (95 % CI -0.028, -0.009) in EQ5D and -0.076 reduction (95 % CI -0.115, -0.052) in AQ5D utilities. An increase by one standard deviation in comorbidity score relative to the mean was associated with a change of -0.029 (95 % CI -0.043, -0.016) in EQ5D and -0.010 (95 % CI -0.020, -0.004) in AQLQ utilities. The impact of comorbidity was greater than asthma symptom control in explaining EQ5D variance (12 vs. 1 %) but smaller in explaining AQ5D variance (3 vs. 12 %).

CONCLUSIONS

Generic and disease-specific HRQoL instruments differentially capture the impact of symptom control and comorbidity in asthma. The selection of HRQoL instruments for asthma studies should depend on the prevalence of comorbidity in the target population and the impact of interventions on asthma control and comorbidity.

Factors affecting ambulance utilization for asthma attack treatment: understanding where to target interventions

OBJECTIVES

Asthma is a serious, sometimes fatal condition, in which attacks vary in severity, potentially requiring emergency medical services (EMS) ambulance treatment. A portion of asthma attacks requiring EMS ambulance treatment may be prevented with improved education and access to care. The aim of this study was to identify areas of the city with high rates of utilization of EMS ambulance for treatment, and the demographics, socio-economic status, and time of day associated with these rates, to better target future interventions to prevent emergencies and reduce cost.

STUDY DESIGN

A cross-sectional study was conducted on individuals in Houston, TX (USA) requiring ambulance treatment for asthma attacks from 2004 to 2011.

METHODS

12,155 EMS ambulance-treated asthma attack cases were linked to census tracts. High rate treatment areas were identified with geospatial mapping. Census tract demographic characteristics of these high rate areas were compared with the remainder of the city using logistic regression. The association between case level demographics and the time of day of asthma attack within the high rate area was also assessed with logistic regression.

RESULTS

EMS ambulance-treated high rate areas were identified and found to have a utilization incidence rate over six times higher per 100,000 people than the remainder of the city. There is an increased risk of location in this high rate area with a census tract level increase of percent of population: earning less than $10,000 yearly income (RR 1.21, 1.16-1.26), which is black (RR 1.08, 1.07-1.10), which is female (RR 1.34, 1.20-1.49) and have obtained less than a high school degree (RR 1.02, 1.01-1.03). Within the high rate area, case level data indicates an increased risk of requiring an ambulance after normal doctor office hours for men compared with women (RR 1.13, 1.03-1.22), for black compared with Hispanic ethnicity (RR 1.31, 1.08-1.59), or for adults (less than 41 and greater than 60) compared with children.

CONCLUSIONS

Interventions to prevent asthma emergencies should be targeted in the high rate area and towards groups identified most at risk. Consideration should be given to improved access to care after normal doctor office hours in these locations. While ambulance treatment reflects the most urgent care needs, these interventions are also expected to reduce the need for emergency room visits.

Integrated traditional Chinese medicine for childhood asthma in Taiwan: a Nationwide cohort study

Background

Traditional Chinese medicine (TCM) is the most commonly used alternative therapy in children with asthma, especially in the Chinese community. This study aimed to investigate the effects of the government-sponsored Outpatient’s Healthcare Quality Improvement (OHQI) project with integrated TCM treatment on childhood asthma.

Methods

This study used the Longitudinal Health Insurance Database 2000, which is a part of the Taiwan National Health Insurance Research Database (NHIRD). Children with diagnosed asthma and aged under 15 years from 2006–2010 were enrolled. They were collated into 3 groups: (1) subjects treated with non-TCM; (2) subjects treated with single TCM; and (3) subjects treated with integrative OHQI TCM. The medical visits and the cost of treatment paid by the Bureau of National Health Insurance (BNHI) to the outpatient, emergency room, and inpatient departments were evaluated for the study subjects within 1 year of the first asthma diagnosis during the study period.

Results

Fifteen multi-hospitals, including 7 medical centers, and 35 TCM physicians participated in OHQI during the study period. A total of 12850 children from the NHIRD database were enrolled in this study, and divided as follows: 12435 children in non-TCM group, 406 children in single TCM group, and 9 children in integrative OHQI TCM group. Although the total medical cost paid by the BNHI per patient in the integrative OHQI TCM group was greater than that in the non-OHQI groups, the patients in the integrative OHQI TCM group exhibited greater therapeutic effects, and did not require ER visits or hospitalization. In addition, ER visits and hospitalization among patients who received a combination of conventional therapy with integrated TCM were lower than those among patients who underwent conventional therapy alone or single TCM treatment.

Conclusions

Asthmatic children at partly controlled level under conventional therapy may benefit from adjuvant treatment with integrated TCM.

Asthma Control and Cost in Latin America

OBJECTIVE

Few patients with asthma have disease that is well-controlled, particularly in Latin American countries. The purpose of this study was to investigate whether partly controlled and uncontrolled asthma are associated with increased costs for asthma-related medications and health care utilization compared with well-controlled asthma in five Latin American countries.

METHODS

Using the Global Initiative for Asthma guidelines, we classified respondents from the Latin American Asthma Insights and Management survey into those with well-controlled, partly controlled, and uncontrolled asthma and compared the utilization of health care services and costs among these groups.

RESULTS

Most respondents to our survey (93%) had asthma that was classified as partly controlled or uncontrolled. Across all countries, patients whose asthma was partly controlled or uncontrolled had greater use of asthma-related medications and medical services than did patients whose asthma was well-controlled. After adjusting for age, sex, and country of residence, total costs for asthma-related medications and health care were greater in patients whose asthma was classified as partly controlled and uncontrolled.

CONCLUSIONS

Our findings indicate that patients with asthma that are not well-controlled used more health care resources and had greater medical costs in Latin America.

Using community level strategies to reduce asthma attacks triggered by outdoor air pollution: a case crossover analysis

BACKGROUND

Evidence indicates that asthma attacks can be triggered by exposure to ambient air pollutants, however, detailed pollution information is missing from asthma action plans. Asthma is commonly associated with four criteria pollutants with standards derived by the United States Environmental Protection Agency. Since multiple pollutants trigger attacks and risks depend upon city-specific mixtures of pollutants, there is lack of specific guidance to reduce exposure. Until multi-pollutant statistical modeling fully addresses this gap, some guidance on pollutant attack risk is required. This study examines the risks from exposure to the asthma-related pollutants in a large metropolitan city and defines the city-specific association between attacks and pollutant mixtures. Our goal is that city-specific pollution risks be incorporated into individual asthma action plans as additional guidance to prevent attacks.

METHODS

Case-crossover analysis and conditional logistic regression were used to measure the association between ozone, fine particulate matter, nitrogen dioxide, sulfur dioxide and carbon monoxide pollution and 11,754 emergency medical service ambulance treated asthma attacks in Houston, Texas from 2004-2011. Both single and multi-pollutant models are presented.

RESULTS

In Houston, ozone and nitrogen dioxide are important triggers (RR = 1.05; 95% CI: 1.00, 1.09), (RR = 1.10; 95% CI: 1.05, 1.15) with 20 and 8 ppb increase in ozone and nitrogen dioxide, respectively, in a multi-pollutant model. Both pollutants are simultaneously high at certain times of the year. The risk attributed to these pollutants differs when they are considered together, especially as concentrations increase. Cumulative exposure for ozone (0-2 day lag) is of concern, whereas for nitrogen dioxide the concern is with single day exposure. Persons at highest risk are aged 46-66, African Americans, and males.

CONCLUSIONS

Accounting for cumulative and concomitant outdoor pollutant exposure is important to effectively attribute risk for triggering of an asthma attack, especially as concentrations increase. Improved asthma action plans for Houston individuals should warn of these pollutants, their trends, correlation and cumulative effects. Our Houston based study identifies nitrogen dioxide levels and the three-day exposure to ozone to be of concern whereas current single pollutant based national standards do not.

Community-based interventions in asthma

Community and public health interventions provide potentially powerful means of decreasing morbidity, hospitalizations, emergency room visits, and mortality from asthma. This chapter thus provides an overview of community-based interventions, which have been demonstrated to be effective-and/or ineffective-in reducing the burden of disease, including development of asthma coalitions, interventions for both provider and patient education, environmental controls to reduce exposure to asthma triggers, and institutional policy and systems change. Perhaps most important is the demonstrated effect of integrated, comprehensive approaches to asthma management and control. A multidisciplinary approach spanning T1 through T4 translational research, coupled with public health activities is promising and has already demonstrated success in reducing the burden of disease.

Impermeable dust mite covers in the primary and tertiary prevention of allergic disease: a meta-analysis

BACKGROUND

Up to 40% of the world's population has been diagnosed with an allergic disease. The most prevalent allergy is to house dust mites. Impermeable mattress covers are often the first treatment in the prevention and decrease of symptoms of allergic disease.

OBJECTIVE

To perform a meta-analysis evaluating the effectiveness of impermeable mattress covers in the primary prevention of allergic disease and as a single intervention in the tertiary prevention of allergic disease symptoms.

METHODS

MEDLINE, Embase, Web of Science, and CINAHL were systematically searched for relevant publications. Seven primary prevention trials (n = 3,461) and 17 tertiary prevention trials (n = 1,671) met the inclusion criteria and were included in the review. All article reviews and abstractions were performed in duplicate.

RESULTS

No significant pooled relative risks were found for the prevention of allergic disease. The pooled relative risks were 0.97 (95% confidence interval [CI] 0.62-1.51) for house dust mite sensitization, 0.92 (95% CI 0.81-1.05) for wheeze, 0.85 (95% CI 0.70-1.02) for asthma, 1.03 (95% CI 0.90-1.19) for allergic rhinitis, and 1.05 (95% CI 0.84-1.32) for allergic dermatitis. Likewise, no significant pooled standardized mean differences were found in the tertiary prevention of symptoms. The pooled standardized mean differences were -0.03 (95% CI -0.15 to 0.09) for peak flow, -0.06 (95% CI -0.32 to 0.20) for asthma symptom score, and -0.39 (95% CI -0.88 to 0.11) for nasal symptom score. A significant effect was seen in the decrease of house mite dust level in the mattress (-0.79, 95% CI -0.98 to -0.60).

CONCLUSION

No evidence was found to support the use of impermeable mattress covers in the primary prevention of allergic disease or in the tertiary prevention of allergic disease symptoms.

Connecting at-risk inpatient asthmatics to a community-based program to reduce home environmental risks: care system redesign using quality improvement methods

INTRODUCTION

Connecting patients admitted with asthma to community-based services could improve care and more efficiently allocate resources. We sought to develop and evaluate an intervention to mitigate in-home environmental hazards (eg, pests, mold) for such children.

METHODS

This was a controlled, quality improvement study on the inpatient units of an urban, academic children's hospital. Clinicians and public health officials co-developed processes to identify children with in-home risks and refer them for assessment and remediation. Processes assessed were the rate at which those identified as eligible were offered referrals, those referred received inspections, and primary care physicians (PCPs) were notified of risks and referrals. Consecutively occurring and seasonally matched intervention (n = 30) and historical control (n = 38) subcohorts were compared with respect to postdischarge mitigating actions (eg, discussions with landlords, PCPs), remaining risks, and morbidity (symptom-free days in previous 2 weeks and Child Asthma Control Test scores).

RESULTS

In the first year, the percentage of eligible children offered referrals increased to a sustained rate of ∼90%; ∼65% of referrals led to in-home inspections (n = 50); and hazards were abated in 30 homes. PCP notification increased from 50% to ∼80%. After discharge, referred parents were more likely to discuss concerns with landlords, the health department, attorneys, and PCPs than patients admitted preimplementation (all P < .05). Referred households were more likely to report reduced presence of ≥2 exposures (P < .05). No differences in asthma morbidity were observed.

CONCLUSIONS

We integrated environmental hazard mitigation into inpatient care. Community-engaged care delivery that reduces risks for poor asthma outcomes can be initiated within the hospital.

Significant association between GSTT1 null genotype and risk of asthma during childhood in Caucasians

Asthma is a complex multifactorial disorder and its management requires a better understanding of its various pathogenesis and mechanisms. Previous studies assessing the association between glutathione S-transferase T1 (GSTT1) null genotype and asthma risk during childhood reported conflicting results. To get a more precise estimation of the association between GSTT1 null genotype and risk of asthma during childhood, we performed a meta-analysis of 16 studies with a total of 18,558 subjects. Subgroup analyses were performed by ethnicity. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 %CI) was used to assess the association. Overall, there was a significant association between GSTT1 null genotype and increased risk of children asthma (OR = 1.25, 95 % CI, 1.02-1.54; P = 0.032). Subgroup analyses showed GSTT1 null genotype was associated with increased risk of children asthma in Caucasians (OR = 1.46, 95 % CI, 1.04-2.03; P = 0.027), but not in Asians (OR = 1.03, 95 % CI, 0.55-1.94; P = 0.928) and Africans (OR = 1.33, 95 % CI, 0.92-1.91; P = 0.127). There was no evidence of publication bias in the subgroup analysis of Caucasians. In conclusion, there is a significant association between GSTT1 null genotype and risk of asthma during childhood in Caucasians. More well-designed epidemiological studies are needed to further assess this association in Asians and Africans.