The role of air pollution in asthma and other pediatric morbidities

A growing body of research supports the role of outdoor air pollutants in acutely aggravating chronic diseases in children, and suggests that the pollutants may have a role in the development of these diseases. This article reviews the biologic basis of children's unique vulnerability to highly prevalent outdoor air pollutants, with a special focus on ozone, respirable particulate matter (PM 2.5 [<2.5 microm in diameter] and PM 10 [<10 microm in diameter]), lead, sulfur dioxide, carbon monoxide, and nitrogen oxides. We also summarize understanding regarding health effects and molecular mechanisms of action. Practitioners can significantly reduce morbidity in children and other vulnerable populations by advising families to minimize pollutant exposures to children with asthma, or at a broader level by educating policymakers about the need to act to reduce pollutant emissions. Management of children with asthma must expand beyond preventing exposures to agents that directly cause allergic reactions (and therefore can be diagnosed by means of skin tests) and must focus more attention on agents that cause a broad spectrum of nonspecific, generalized inflammation, such as air pollution.     

Circulating neutrophil CD14 expression and the inverse association of ambient particulate matter on lung function in asthmatic children.

BACKGROUND: Identifying baseline inflammatory biomarkers that predict susceptibility to size-specific particulate matter (PM) independent of gaseous pollutants could help us better identify asthmatic subpopulations at increased risk for the adverse health effects of PM. OBJECTIVE: To evaluate whether the association between lung function and exposure to ambient levels of PM less than 2.5 microm in diameter (PM2.5) (fine) and 10 to 2.5 microm in diameter (PM(10-2.5)) (coarse) in children with persistent asthma differed across baseline measures of inflammation and innate immune activation. METHODS: We performed a panel study on a local population of 16 children with persistent asthma and evaluated daily pulmonary function (percentage of predicted peak expiratory flow and forced expiratory volume in 1 second) while concurrently measuring daily PM2.5 and PM(10-2.5) exposure from a central site in Chapel Hill, North Carolina. The children underwent a baseline medical evaluation that included assessment of several immunoinflammatory biomarkers in peripheral blood. RESULTS: Children without measurable CD14 expression on circulating neutrophils had significantly reduced pulmonary function (forced expiratory volume in 1 second and peak expiratory flow) with each interquartile range (IQR) increase in PM2.5 (IQR = 8.5 microg/m3) and PM(10-2.5) (IQR = 4.1 microg/m3) concentration, unlike children with measurable CD14 expression (P < .001 for interaction). CONCLUSIONS: Asthmatic children with muted surface expression of CD14 on circulating neutrophils may have a decreased capacity to respond to bacterial components of PM.     

Traffic and outdoor air pollution levels near residences and poorly controlled asthma in adults.

BACKGROUND: Air pollution may exacerbate asthma. OBJECTIVE: To investigate associations between traffic and outdoor air pollution levels near residences and poorly controlled asthma among adults diagnosed as having asthma in Los Angeles and San Diego counties, California. METHODS: We estimated traffic density within 500 ft of 2001 California Health Interview Survey respondents' reported residential cross-street intersections. Additionally, we assigned annual average concentrations of ozone, nitrogen dioxide, particulate matter 2.5 and 10 micrometers or less in diameter, and carbon monoxide measured at government monitoring stations within a 5-mile radius of the reported residential cross-street intersections. RESULTS: We observed a 2-fold increase in poorly controlled asthma (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.38-3.23) among asthmatic adults in the highest quintile of traffic density after adjusting for age, sex, race, and poverty. Similar increases were seen for nonelderly adults, men, and women, although associations seemed strongest in elderly adults (OR, 3.00; 95% CI, 1.13-7.91). Ozone exposures were associated with poorly controlled asthma among elderly adults (OR, 1.70; 95% CI, 0.91-3.18 per 1 pphm) and men (OR, 1.76; 95% CI, 1.05-2.94 per 1 pphm), whereas particulate matter 10 micrometers or less seemed to affect primarily women (OR, 2.06; 95% CI, 1.17-3.61), even at levels below the national air quality standard. CONCLUSIONS: Heavy traffic and high air pollution levels near residences are associated with poorly controlled asthma.     

Effects of air pollution on asthma hospitalization rates in different age groups in Hong Kong

AIMS: To assess the relationship between levels of ambient air pollutants and hospitalization rates for asthma in Hong Kong (HK). METHODS: This is a retrospective ecological study. Data of daily emergency hospital admissions to 15 major hospitals in HK for asthma and indices of air pollutants [sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm particulate matter (PM(10)) and 2.5 microm (PM(2.5))] and meteorological variables from January 2000 to December 2005 were obtained from several government departments. Analysis was performed by the generalized additive models with Poisson distribution. The effects of time trend, season, other cyclical factors, temperature and humidity were adjusted. Autocorrelation and overdispersion were corrected. RESULTS: Altogether, 69 716 admissions were assessed. Significant associations were found between hospital admissions for asthma and levels of NO(2), O(3), PM(10) and PM(2.5). The relative risks (RR) for hospitalization for every 10 microg/m(3) increase in NO(2), O(3), PM(10) and PM(2.5) were 1.028, 1.034, 1.019 and 1.021, respectively, at a lag day that ranged from cumulative lag 0-4 to 0-5. In a multi-pollutant model, O(3) was significantly associated with increased admissions for asthma. The younger age group (0-14 years) tended to have a higher RR for each 10 microg/m(3) increase in pollutants than those aged 15-65 years. The elderly (aged >/=65 years) had a shorter 'best' lag time to develop asthma exacerbation following exposure to pollutants than those aged <65 years. CONCLUSION: Adverse effects of ambient concentrations of air pollutants on hospitalization rates for asthma are evident. Measures to improve air quality in HK are urgently needed.     

Residential outdoor air pollution and allergen sensitization in schoolchildren in Oslo, Norway

BACKGROUND: Epidemiological studies that have investigated the association between air pollution and atopy have found inconsistent results. Furthermore, often exposure to outdoor air pollution has had limited quality, and more individual exposure is needed. OBJECTIVE: To investigate the relations between early and lifetime exposure to residential outdoor air pollution and allergen sensitization in 9-10-year-old children in Oslo, Norway. METHODS: Sensitization to common allergens was measured by skin prick tests (SPTs), which were performed in 2244 children who had lived in Oslo since birth. Several definitions of positive SPT were used. Information on potential confounding variables was collected by a parental questionnaire. Exposure to outdoor air pollution was assessed by the EPISODE dispersion model, which calculates hourly concentrations of nitrogen dioxide (NO2), particulate matter (PM) with aerodynamic diameter <10 microm (PM10) and <2.5 microm (PM2.5), respectively. RESULTS: We found no associations between long-term air pollution exposure and sensitization to any allergen, any indoor or any pollen allergen. However, lifetime air pollution exposure was associated with sensitization to the house dust mite Dermatophagoides farinae. One interquartile increase of lifetime exposure to NO2, PM10 and PM2.5 was associated with 1.88 (adjusted odds ratio) (1.02, 3.47) [95% confidence interval (CI)], 1.61 (0.96, 2.72) and 1.46 (0.96, 2.22), respectively, for D. farinae. Lifetime exposure was also associated with sensitization to cat in a subpopulation. Both associations diminished after adjusting for a contextual socio-economic factor. CONCLUSION: Long-term exposure to traffic-related pollutants was generally not associated with allergen sensitization in 9-10-year-old Oslo children. However, lifetime exposure was associated with sensitization to D. farinae, and with sensitization to cat in a subpopulation, which may be explained by socio-economic confounding or multiple comparisons. The air pollution levels in Oslo may be too low to reveal associations with sensitization.     

Association between air pollution and asthma admission among children in Hong Kong

OBJECTIVE: To examine the association of air pollutants with hospital admission for childhood asthma in Hong Kong. METHODS: Data on hospital admissions for asthma, influenza and total hospital admissions in children aged < or =18 years at all Hospital Authority hospitals during 1997-2002 were obtained. Data on daily mean concentrations of particles with aerodynamic diameter <10 microm (i. e. PM10) and <2.5 microm (i. e. PM2.5), nitrogen dioxide (NO2), sulphur dioxide (SO2), and ozone (O3) and data on meteorological variables were associated with asthma hospital admissions using Poisson's regression with generalized additive models for correction of yearly trend, temperature, humidity, day-of-week effect, holiday, influenza admissions and total hospital admission. The possibility of a lag effect of each pollutant and the interaction of different pollutants were also examined. RESULTS: The association between asthma admission with change of NO2, PM10, PM2.5 and O3 levels remained significant after adjustment for multi-pollutants effect and confounding variables, with increase in asthma admission rate of 5.64% (3.21-8.14) at lag 3 for NO2, 3.67% (1.52-5.86) at lag 4 for PM10, 3.24% (0.93-5.60) at lag 4 for PM2.5 and 2.63% (0.64-4.67) at lag 2 for O3. Effect of SO2 was lost after adjustment. CONCLUSION: Ambient levels of PM10, PM2.5) NO2 and O3 are associated with childhood asthma hospital admission in Hong Kong.     

Temporal change in the prevalence of respiratory symptoms and obstructive airways disease 1993–2001

BACKGROUND: There has been little available information regarding secular changes in the prevalence of respiratory symptoms since the mid-1990s. AIM: To examine changes in the prevalence of respiratory symptoms for 1993-2001. DESIGN OF STUDY: A series of postal questionnaire surveys. SETTING: Two general practice populations, including all age groups. METHOD: Four postal respiratory questionnaire surveys were conducted between 1993 and 2001. Subjects who replied to two or more surveys (8058 adults and 2350 children) were included in the main analyses. Validated scoring systems were used to define obstructive airways disease in adults and asthma in children. RESULTS: Over the 8-year observation period there were increases among adults in the crude prevalence of wheeze, being woken by cough, receipt of current asthma medication, and of obstructive airways disease, compared with decreases in children for wheeze, night cough, asthma attacks, and asthma. For adults, adjusted odds ratios per year of secular increase were 1.03 (95% confidence interval [CI] = 1.02 to 1.03) for wheeze, 1.03 (95% CI = 1.02 to 1.03) for being woken by cough, 1.03 (95% CI = 1.02 to 1.04) for asthma medication, and 1.02 (95% CI = 1.01 to 1.03) for obstructive airways disease. These increases were greater in those aged over 44 years, in males, and in those without a family history of asthma or a history of hayfever or eczema. Corresponding decreases for children were 0.94 (95% CI = 0.92 to 0.97) for wheeze, 0.93 (95% CI = 0.91 to 0.96) for night cough, 0.93 (95% CI = 0.90 to 0.95) for asthma attacks and 0.98 (95% CI = 0.95 to 1.00) for asthma. CONCLUSION: The increases found in adults are more likely to be due to chronic obstructive pulmonary disease (COPD) than asthma. This is supported by the decreases in symptom and asthma prevalence in children.     

Fine particulate air pollution and mortality in 20 U.S. cities, 1987-1994

BACKGROUND: Air pollution in cities has been linked to increased rates of mortality and morbidity in developed and developing countries. Although these findings have helped lead to a tightening of air-quality standards, their validity with respect to public health has been questioned. METHODS: We assessed the effects of five major outdoor-air pollutants on daily mortality rates in 20 of the largest cities and metropolitan areas in the United States from 1987 to 1994. The pollutants were particulate matter that is less than 10 microm in aerodynamic diameter (PM10), ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. We used a two-stage analytic approach that pooled data from multiple locations. RESULTS: After taking into account potential confounding by other pollutants, we found consistent evidence that the level of PM10 is associated with the rate of death from all causes and from cardiovascular and respiratory illnesses. The estimated increase in the relative rate of death from all causes was 0.51 percent (95 percent posterior interval, 0.07 to 0.93 percent) for each increase in the PM10 level of 10 microg per cubic meter. The estimated increase in the relative rate of death from cardiovascular and respiratory causes was 0.68 percent (95 percent posterior interval, 0.20 to 1.16 percent) for each increase in the PM10 level of 10 microg per cubic meter. There was weaker evidence that increases in ozone levels increased the relative rates of death during the summer, when ozone levels are highest, but not during the winter. Levels of the other pollutants were not significantly related to the mortality rate. CONCLUSIONS: There is consistent evidence that the levels of fine particulate matter in the air are associated with the risk of death from all causes and from cardiovascular and respiratory illnesses. These findings strengthen the rationale for controlling the levels of respirable particles in outdoor air.     

Air pollution and daily mortality in Inchon, Korea.

The association between total daily mortality and air pollution was investigated for a 1-year period (January 1995 to December 1995) in Inchon, Korea. The purpose of this study was to evaluate the relative importance of particulate and gaseous air pollution as predictors of daily mortality. Concentration of total suspended particulates (TSP), inhalable particles (PM10), and gaseous pollutants, such as sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, were measured daily during the study period. A generalized additive model was used to regress daily death counts on each air pollutant, controlling for time trend and meteorologic influences such as temperature or relative humidity. Total mortality was found to increase 1.2% (95% CI: 0.2 to 2.2%) for each 10 microg/m3 increase in 6-day moving average of TSP, and 1.2% (95% CI 0.2 to 2.1%) for each 10 microg/m3 increase in 5-day moving average of PM10. The association is similar in magnitude to associations between particulate air pollution and mortality found in several other communities in America and Europe. Associations with gaseous pollutants were all statistically insignificant in the generalized additive model. The relative risk of death increased at particulate levels that were well below the current Korean Ambient Air Quality Standard.     

Nasal inflammation and personal exposure to fine particles PM2.5 in asthmatic children

BACKGROUND: Outdoor and indoor air pollutants are suspected to induce harmful effects on respiratory health, raising the question of their involvement in allergic asthma and rhinitis. OBJECTIVE: The potential effect of short-term personal exposure to particulate matter with a diameter of less than 2.5 microm (PM2.5) on nasal inflammation was examined in children living in the Paris area. METHODS: Forty-one children with allergic asthma and 44 healthy children participated in this study. They were monitored during 48 hours for their personal exposure to PM2.5. At the end of the measurement period, children underwent one nasal lavage. Nasal lavage fluid was investigated for cellular (neutrophils and eosinophils) and soluble (albumin, urea, elastase, alpha1-antitrypsin, IL-6, and IL-8) mediators. RESULTS: Pollutant concentrations did not differ between the 2 groups. In asthmatic subjects, but not in healthy children, personal PM2.5 levels were correlated to nasal percentage of eosinophils and to albumin, urea, and alpha1-antitrypsin concentrations after adjustment for confounders (age, sex, house dust mites, pollens, cat, environmental tobacco smoke through urinary cotinine, barometric pressure, and respiratory infection). CONCLUSION: The association observed with the percentage of eosinophils supports recent speculations on fine particle involvement in allergic phenotype overexpression. CLINICAL IMPLICATIONS: This study highlights the link between personal fine particle exposures and nasal inflammation in asthmatic allergic children living in urban areas. Because the view of united airways is still not completely understood, the question of pulmonary inflammation in such a situation deserves further investigation.     

Long-term exposure to background air pollution related to respiratory and allergic health in schoolchildren

BACKGROUND: The impact of air pollution on asthma and allergies still remains a debate. OBJECTIVE: Our cross-sectional study was intended to analyse the associations between long-term exposure to background air pollution and atopic and respiratory outcomes in a large population-based sample of schoolchildren. METHODS: Six thousand six hundred and seventy-two children aged 9-11 years recruited from 108 randomly schools in six French cities underwent a clinical examination including a skin prick test (SPT) to common allergens, exercise-induced bronchial reactivity (EIB) and skin examination for flexural dermatitis. The prevalence of asthma, allergic rhinitis (AR) and atopic dermatitis was assessed by a standardized health questionnaire completed by the parents. Three-year-averaged concentrations of air pollutants (NO2, SO2, PM10 and O3) were calculated at children' schools using measurements of background monitoring stations. RESULTS: After adjusting for confounders, EIB, lifetime asthma and lifetime AR were found to be positively related to an increase in the exposure to SO2, PM10 and O3. The adjusted odds ratios (aOR) per increase of 5 microg/m3 of SO2 was 1.39 (95% confidence interval (CI)=1.15-1.66) for EIB and 1.19 (1.00-1.41) for lifetime asthma. The aOR for lifetime AR per increase of 10 microg/m3 of PM10 was 1.32 (CI=1.04-1.68). Moreover, SPT positivity was associated with O3 (aOR=1.34; CI=1.24-1.46). Associations with past year symptoms were consistent, even if not always statistically significant. Results persisted in long-term resident (current address for at least 8 years) children. However, no consistent positive association was found with NO2. CONCLUSIONS: A moderate increase in long-term exposure to background ambient air pollution was associated with an increased prevalence of respiratory and atopic indicators in children.     

Are the asthma guideline goals achieved in daily practice? A population-based study on treatment adequacy and the control of asthma

BACKGROUND: The guidelines for asthma recommend that the use of anti-inflammatory therapy should be adapted to the severity of the disease. However, few data are available to assess the adequacy of the use of drugs and its influence on the control of asthma in 'real life'. METHODS: The adequacy of the current use of anti-asthmatic medication according to the Global Initiative for Asthma (GINA) guidelines was assessed in a random sample of 400 asthmatics identified in the frame of the Italian Study on Asthma in Young Adults. Asthma severity was assessed using the GINA criteria; accordingly, a patient was classified as receiving inadequate treatment if his/her current use of drugs was lower than that suggested by the guidelines for the corresponding severity level. The absence of asthma attacks in the last 3 months was used as an indicator of the disease control. RESULTS: Fifty-five percent of the patients had persistent asthma. Overall, 48% (95% CI 41.2-54.8) of persistent asthmatics were receiving inadequate treatment, and 66% (95% CI 59.5-72.4) had not used their medication daily over the past 3 months. Persistent asthmatics who were inadequately treated had a significantly greater frequency of asthma attacks (geometric mean ratio 3.7; 95% CI 2.1-6.6) than those using an adequate dose of medication. Mild and moderate persistent asthmatics using an adequate medication regimen reported a low number of asthma attacks (median 0). At the multivariate analysis, a good control of the disease was positively associated with an adequate dose of anti-inflammatory medication (OR = 2.2; 95% CI 1.1-4.5) and was negatively associated with a later onset of asthma (OR = 0.96; 95% CI 0.93-0.99) and severe asthma (OR = 0.37; 95% CI 0.17-0.81). CONCLUSIONS: Despite the increase in the use of inhaled corticosteroids, half of the persistent asthmatics from the general population are using a medication regimen below their severity level. When the use of drugs follows the GINA guideline recommendations, a good control of asthma is also achievable in the daily management of the disease, particularly in the case of mild and moderate asthmatics.     

How and by whom care is delivered influences anti-inflammatory use in asthma: Results of a national population survey

BACKGROUND: Studies examining the influence of provider behavior and patterns of care delivery on the use of anti-inflammatory asthma therapy have been limited to selected populations or have been unable to assess the appropriateness of therapy for individuals. We have previously reported the influence of sociodemographic variables and asthma severity on reported use of asthma medications in the United States. OBJECTIVE: We sought to examine the influence of patterns of care delivery and clinician behavioral factors on the use of anti-inflammatory medication by patients with asthma. METHODS: We performed a cross-sectional national random digit dial household telephone survey in 1998 of adult patients and parents of children with current asthma. Respondents were classified as having current asthma if they had a physician's diagnosis of asthma and were either taking medication for asthma or had asthma symptoms during the past year. RESULTS: One or more persons met the study criteria for current asthma in 3273 (7.8%) households in which a screening questionnaire was completed. Of the 2509 persons (721 children <16 years of age) with current asthma interviewed, 507 (20.1%) reported current use of anti-inflammatory medication. In a multiple logistic regression model controlling for asthma symptoms, reported anti-inflammatory use was significantly associated with patients reporting their physician having an excellent ability to explain asthma management (odds ratio [OR], 1.47; 95% CI, 1.09-1.98), scheduling regular visits to a physician for asthma (OR, 1.30; 95% CI, 1.02-1.64), having a written asthma action plan (OR, 1.63; 95% CI, 1.29-2.06), and being of white, non-Hispanic ethnicity (OR, 1.53; 95% CI, 1.19-1.98), along with markers of greater asthma morbidity, missing 6 or more days from work or school in the past year (OR, 1.29; 95% CI, 1.01-1.65), and hospitalization for asthma in the past year (OR, 1.74; 95% CI, 1.19-2.53). Anti-inflammatory use was less likely to be reported with younger age (OR, 0.82; 95% CI, 0.73-0.94), lower long-term asthma symptom burden (OR, 0.82; 95% CI, 0.71-0.94), use of 4 or fewer reliever inhaler canisters in the past year (OR, 0.50; 95% CI, 0.43-0.58), and smoking (OR, 0.50; 95% CI, 0.37-0.68). CONCLUSION: How asthma care is delivered influences the use of anti-inflammatory medication. Strategies to increase regular evaluation by a physician interested in asthma, particularly for minority patients, and to increase a physician's ability to communicate asthma management to patients might improve use of anti-inflammatory therapy among patients with asthma.     

Household mouse allergen exposure and asthma morbidity in inner-city preschool children.

BACKGROUND: Inner-city children experience disproportionate asthma morbidity, and suspected reasons include indoor environmental exposures. OBJECTIVE: To determine if mouse allergen exposure is a risk factor for asthma morbidity. METHODS: Preschool children with asthma were recruited from inner-city Baltimore, MD. Skin testing was performed and blood was collected at the baseline visit for quantification of mouse allergen specific IgE. A questionnaire evaluated symptoms, medication, and health care use at baseline, 3 months, and 6 months. A trained technician collected dust samples from the child's home for analysis of Mus m 1 at baseline, 3 months, and 6 months. Outcomes were compared between mouse-sensitized, highly exposed children and all other children. RESULTS: A total of 127 children had complete data for mouse sensitization status and bedroom settled dust mouse allergen levels at baseline. The mean age of the children was 4.4 years, 92% were African American, and 26% were sensitized to mouse. Mouse-sensitized children exposed to higher levels of Mus m 1 (>0.5 microg/g) had 50% more days of symptoms (incidence rate ratio [IRR], 1.5; 95% confidence interval [CI], 1.1-2.1) and 80% more days of beta-agonist use than other children (IRR, 1.8; 95% CI, 1.3-2.5). Children in the sensitized and highly exposed group were also more likely to have an unscheduled physician visit (odds ratio [OR], 3.1; 95% CI, 1.6-6.3), emergency department visit (OR, 2.1; 95% CI, 1.1-4.1), and hospitalization (OR, 36.6; 95% CI, 4.1-327.3) than other children. These associations between mouse allergen exposure and asthma symptoms and morbidity remained statistically significant after adjusting for potential confounders, including atopy and cockroach sensitization and exposure. CONCLUSIONS: In mouse-sensitized inner-city children, exposure to mouse allergen may be an important cause of asthma morbidity.     

Antibiotic use in early childhood and the development of asthma

BACKGROUND AND OBJECTIVE: Recent investigations have focused on the role of infections in infancy in promoting or protecting against the subsequent development of asthma. A related hypothesis concerns the possible role of medical responses to infections, including the widespread use of antibiotics. We chose children at Rudolf Steiner schools to test this latter hypothesis because a significant proportion of parents rejects the use of conventional treatments, including antibiotics. METHODS: Seventy-five per cent (n = 456) of parents of children aged 5-10 years attending Rudolf Steiner schools throughout New Zealand completed questionnaires which included questions on the use of antibiotics and a history of asthma and wheeze in their children. RESULTS: After controlling for potential confounders, antibiotic use was significantly associated with having a history of asthma (OR = 2.74, 95% CI: 1.10-6.85) or wheeze (OR = 1. 86, 95% CI: 1.06-3.26) but not with current wheeze (OR = 1.08, 95% CI: 0.54-2-16). The adjusted odds ratio for asthma was 4.05 (95% CI: 1.55-10.59) if antibiotics were used in the first year of life and 1. 64 (95% CI: 0.60-4.46) if antibiotics had been used only after the first year of life when compared with children who had never used antibiotics. The number of courses of antibiotics during the first year of life was also associated with increased odds ratios for asthma: 2.27 (95% CI: 1.14-4.51) for one to two courses and 4.02 (95% CI: 1.57-10.31) for three or more courses when compared with no antibiotic use in the first year of life. Although not significant, the association of antibiotics and hay fever (OR = 1.99 [95% CI: 0. 93-4.26]) was of a similar strength to the association of antibiotics with a history of wheeze. Antibiotics were not significantly associated with eczema (OR = 1.23 [95% CI: 0.71-2.13]). CONCLUSION: Antibiotic use in infancy may be associated with an increased risk of developing asthma. Further study is required to determine the reasons for this association.     

Race/ethnicity, language, and asthma care: findings from a 4-state survey.

BACKGROUND: Latino and African American children have poorer asthma control than non-Latino white children, but few studies examine the association among race/ethnicity, language, and specific processes of asthma care. OBJECTIVE: To evaluate the association of race/ethnicity and language with the quality of asthma care. METHODS: A random sample of children from birth to the age of 17 years with asthma within 4 states (California, Texas, Illinois, and Alabama) was selected for the National Asthma Survey conducted by the National Center for Health Statistics from March 1, 2003, to March 10, 2004. Parents completed a telephone survey that included measures of asthma care quality. The final sample was 1,517 children. RESULTS: According to parental report, only 41.4% of children had an asthma management plan and 48.5% were ever advised by a clinician to control asthma by changing the child's home and school environment. African American and Latino children with persistent asthma had lower odds of taking controller medication than non-Latino white children. In multivariate analysis adjusting for annual income, insurance, and age, Latino children with Spanish parental interview, but not African American and Latino children with English parental interview, had poorer experiences with care than white children (ever taught what to do during an attack: odds ratio, 0.4 [95% confidence interval, 0.2-0.6]; and ever advised to change child's home and school environment: odds ratio, 0.5 [95% confidence interval, 0.3-0.8]). CONCLUSIONS: Differences in asthma care quality and controller use persist among racial/ethnic and language groups despite similar rates of planned encounters for asthma. Improving use of controller medications and counseling on environmental modifications are important for reducing asthma disparities.     

Asthma prevalence and morbidity among rural Iowa schoolchildren

BACKGROUND: There are conflicting findings about the prevalence of asthma among farm and nonfarm children. OBJECTIVES: We sought to estimate asthma prevalence and morbidity and determine differences between farm and nonfarm children. METHODS: The study population consisted of all children aged 6 to 14 years enrolled in 10 school districts in 2 noncontiguous rural Iowa counties from 2000 through 2002. The mailed parental screening questionnaire included the International Study of Asthma and Allergies in Childhood core questionnaire, items from the Functional Severity Index, and items on physician diagnosis and medication and urgent care use. RESULTS: The response rate was 86.6%. The 12-month prevalence of wheeze was 19.1%. Self-reported physician diagnosis of asthma was reported by 13.4%. On multivariable analysis controlling for age, sex, and county, children who lived on farms were less likely than those who lived in town to have ever wheezed (odds ratio, 0.71; 95% CI, 0.58-0.87) or to have wheezed during the past year (odds ratio, 0.77; 95% CI, 0.60-0.98). However, this protective association with farming was only observed in one of the study counties. Among those who wheezed, farm and nonfarm children were equally likely to have been given a diagnosis of asthma and had comparable morbidity. CONCLUSION: By using a standardized questionnaire with a high response rate in this large, rural, population-based study, asthma prevalence rivaled that in large Midwestern cities. Unmeasured risk factors might account for the apparent protective effect in Keokuk County. These findings cast doubt on a protective effect of rural life for the development of childhood asthma.     

Increased risk of asthma attacks and emergency visits among asthma patients with allergic rhinitis: a subgroup analysis of the improving asthma control trial

BACKGROUND: Inadequately controlled allergic rhinitis (AR) in asthmatic patients can contribute towards increased asthma exacerbations and poorer symptom control, which may increase medical resource use. We assessed asthma-related medical resource use and attacks in asthmatic patients who did and did not have concomitant AR and were adding montelukast or salmeterol to baseline treatment with inhaled fluticasone. METHODS: A post hoc resource use analysis of a 52-week, double-blind multicentre clinical trial (Investigation of Montelukast as a Partner Agent for Complementary Therapy) [corrected] including 1490 adults with chronic asthma, aged 15-72 years, with FEV(1) 50-90% of predicted and > or =12% increase in FEV(1) after salbutamol administration, treated with either montelukast 10 mg daily or salmeterol 50 microg twice daily in addition to fluticasone 200 microg, was undertaken. Asthma-related medical resource use included medical visits (defined as either an unscheduled visit [to a general practitioner, a specialist or a non-medical provider] or a specialist visit), emergency room visits and hospitalizations during follow-up. Asthma attacks were defined as the worsening of asthma requiring unscheduled visit, emergency visit, hospitalization or oral/intravenous/intramuscular corticosteroids. RESULTS: A self-reported history of concomitant AR was identified in 60% of the patients (n=893). Univariate analysis suggests that significantly more patients with concomitant AR experienced emergency room visits (3.6% vs. 1.7%, P=0.029) and asthma attacks (21.3% vs. 17.1%, P=0.046). Multivariate analysis adjusting for treatment group, age and baseline asthma severity confirmed these results since the presence of concomitant AR in patients with asthma increases the likelihood of emergency room visit (odds ratio (OR)=2.35, 95% confidence interval (CI)=1.12-4.80) and asthma attack (OR=1.35, 95% CI=1.03-1.77). Patients with asthma alone compared with patients with both conditions did not differ in terms of unscheduled or specialist visits and hospitalizations. CONCLUSIONS: Presence of self-reported concomitant AR in patients with asthma resulted in a higher rate of asthma attacks and more emergency room visits compared with asthma patients without concomitant AR.     

Systematic review: Exposure to pets and risk of asthma and asthma-like symptoms

BACKGROUND: Studies of exposure to pets and risk of asthma have yielded conflicting results. OBJECTIVES: We performed a systematic review to synthesize the evidence of the effect of exposure to pets in the home on the risk of asthma and asthma-related symptoms. We also assessed differences between the studies as sources of heterogeneity of the results. METHODS: We conducted a MEDLINE search (until the end of 1999) using the following boolean search command: (asthma[all] OR wheez*[all]) AND (domestic animal*[all] OR pets[all]). The outcome was limited to either diagnosis of asthma or the symptom of wheezing. The exposure of interest was domestic animals in the home. Appropriate temporal relationship was defined as present in studies with either pet keeping within the first 2 years of life, in the past, or exposure to pets preceding the outcome. RESULTS: Thirty-two of the 217 retrieved articles fulfilled the eligibility criteria. Inappropriate time sequence of the exposure and outcome information was an important source of heterogeneity and an indication of potential selection bias. Therefore we analyzed studies focusing on early exposure or ensuring appropriate temporal sequence. The pooled risk estimates for both asthma (fixed-effects odds ratio, 1.11; 95% CI, 0.98-1.25; heterogeneity, P =.04; random-effects odds ratio, 1.09; 95% CI, 0.89-1.34) and wheezing (fixed-effects odds ratio, 1.19; 95% CI, 1.05-1.35; heterogeneity, P =.03; random-effects odds ratio, 1.17; 95% CI, 0.95-1.44) indicated a small effect, which was limited to studies with a median study population age of over 6 years (fixed-effects odds ratio, 1.19; 95% CI, 1.02-1.40; heterogeneity, P =.04; random-effects odds ratio, 1.15; 95% CI, 0.86-1.56; fixed-effects odds ratio, 1.29; 95% CI, 1.12-1.48; heterogeneity, P =.31). In younger children the harmful effect disappeared for wheezing (odds ratio, 0.80; 95% CI, 0.59-1.08; P =.38). CONCLUSION: Exposure to pets appears to increase the risk of asthma and wheezing in older children. The observed lower risk among exposed than among unexposed young children is consistent with a protective effect in this age group but could also be explained by selection bias.