Risk Of Hospitalization For Asthma Research Articles

STROBE-compliant article: Is continuity of care associated with avoidable hospitalization among older asthmatic patients?

Continuity of care (COC) has a proven relationship with health care outcomes. However, evidence regarding an association between COC and avoidable hospitalization for elderly patients with asthma is insufficient.A retrospective cohort study was performed using Taiwanese National Health Insurance claim data from 2004 to 2013. Patients were retrospectively followed for 2 years; the COC index (COCI) for asthma was measured in the 1st year, and avoidable hospitalization for asthma and follow-up time were determined in the subsequent year. Cox proportional hazards regression was employed to examine hazard ratios (HRs) between COC and avoidable hospitalization for asthma after adjustment for confounding factors. Adjusted HR (aHR) was also calculated by stratifying each variable to investigate whether the effect of COC on hospitalization for asthma was avoidable and how this varied across levels of COCI.Of 3356 patients included in this study, 1648 patients (49%) had a COCI of 1, and the average COCI was 0.73. Compared with patients with high COC (COCI = 1), those with low COC (COCI < 0.5) had a significantly higher risk of avoidable hospitalization for asthma (aHR = 2.68; 95% confidence interval [CI]: 1.55–4.63). In addition, after stratified analysis, we determined that COC plays a much more important role for patients who were women, had low insurance premiums, and had no comorbidities.High continuity of ambulatory asthma care is linked to a reduced risk of avoidable hospitalization for asthma in elderly asthmatic patients.

Differential respiratory health effects from the 2008 northern California wildfires: A spatiotemporal approach

We investigated health effects associated with fine particulate matter during a long-lived, large wildfire complex in northern California in the summer of 2008. We estimated exposure to PM2.5 for each day using an exposure prediction model created through data-adaptive machine learning methods from a large set of spatiotemporal data sets. We then used Poisson generalized estimating equations to calculate the effect of exposure to 24-hour average PM2.5 on cardiovascular and respiratory hospitalizations and ED visits. We further assessed effect modification by sex, age, and area-level socioeconomic status (SES). We observed a linear increase in risk for asthma hospitalizations (RR=1.07, 95% CI=(1.05, 1.10) per 5µg/m3 increase) and asthma ED visits (RR=1.06, 95% CI=(1.05, 1.07) per 5µg/m3 increase) with increasing PM2.5 during the wildfires. ED visits for chronic obstructive pulmonary disease (COPD) were associated with PM2.5 during the fires (RR=1.02 (95% CI=(1.01, 1.04) per 5µg/m3 increase) and this effect was significantly different from that found before the fires but not after. We did not find consistent effects of wildfire smoke on other health outcomes. The effect of PM2.5 during the wildfire period was more pronounced in women compared to men and in adults, ages 20–64, compared to children and adults 65 or older. We also found some effect modification by area-level median income for respiratory ED visits during the wildfires, with the highest effects observed in the ZIP codes with the lowest median income. Using a novel spatiotemporal exposure model, we found some evidence of differential susceptibility to exposure to wildfire smoke.

Exposure to extreme heat and precipitation events associated with increased risk of hospitalization for asthma in Maryland, U.S.A.

BackgroundSeveral studies have investigated the association between asthma exacerbations and exposures to ambient temperature and precipitation. However, limited data exists regarding how extreme events, projected to grow in frequency, intensity, and duration in the future in response to our changing climate, will impact the risk of hospitalization for asthma. The objective of our study was to quantify the association between frequency of extreme heat and precipitation events and increased risk of hospitalization for asthma in Maryland between 2000 and 2012.MethodsWe used a time-stratified case-crossover design to examine the association between exposure to extreme heat and precipitation events and risk of hospitalization for asthma (ICD-9 code 493, n = 115,923).ResultsOccurrence of extreme heat events in Maryland increased the risk of same day hospitalization for asthma (lag 0) by 3 % (Odds Ratio (OR): 1.03, 95 % Confidence Interval (CI): 1.00, 1.07), with a considerably higher risk observed for extreme heat events that occur during summer months (OR: 1.23, 95 % CI: 1.15, 1.33). Likewise, summertime extreme precipitation events increased the risk of hospitalization for asthma by 11 % in Maryland (OR: 1.11, 95 % CI: 1.06, 1.17). Across age groups, increase in risk for asthma hospitalization from exposure to extreme heat event during the summer months was most pronounced among youth and adults, while those related to extreme precipitation event was highest among ≤4 year olds.ConclusionExposure to extreme heat and extreme precipitation events, particularly during summertime, is associated with increased risk of hospitalization for asthma in Maryland. Our results suggest that projected increases in frequency of extreme heat and precipitation event will have significant impact on public health.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-016-0142-z) contains supplementary material, which is available to authorized users.

Gestational Age, Birthweight for Gestational Age, and Childhood Hospitalisations for Asthma and Other Wheezing Disorders

Preterm birth, early term birth, and low birthweight are associated with childhood wheezing disorders in developed Western settings, but observed associations could be confounded by socio-economic position. This study aims to clarify such associations in a developed non-Western setting with a different confounding structure. Using Cox regression, we examined the adjusted associations of gestational age and birthweight for gestational age with time to first public hospital admission for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version Clinical Modification 466, 490, and 493) from 9 days to 12 years in a population-representative birth cohort of 8327 Chinese children in Hong Kong, a developed setting with less clear social patterning of prematurity or birthweight. Analyses were adjusted for infant and parental characteristics and socio-economic position. Children born late preterm (34 to <37 weeks) had higher risk of hospitalisation for asthma and other wheezing disorders [hazard ratio (HR) 1.99, 95% confidence interval (CI) 1.48, 2.67] than children born full term (39 to <41 weeks). Early term births (37 to <39 weeks) had HR 1.01 (95% CI 0.84, 1.22), late term births (41 to <42 weeks) had HR 0.77 (95% 0.59, 1.01), and post-term births (≥42 weeks) had HR 0.56 (95% CI 0.32, 0.98). Large for gestational age was associated with lower risk of hospitalisation (HR 0.76, 95% CI 0.57, 0.99). The association of preterm birth with childhood wheezing could be biologically mediated. We cannot rule out an association for early term births.

Acute effects of urban air pollution on respiratory emergency hospital admissions in the Canary Islands

In the cities of Las Palmas (L/P) de Gran Canaria and Santa Cruz (S/C) de Tenerife, Canary Islands, particulate matter is highly influenced by mineral dust because their proximity to the Sahara desert (PM10–2.5 levels are higher than PM2.5). In this context, the short-term association between different PM fractions and gaseous pollutants with emergency hospital admissions for all respiratory, chronic obstructive pulmonary disease (COPD) and asthma was analyzed, evaluating the potential independent effect of PM10–2.5. A generalized additive model was fitted controlling for seasonal patterns and time varying confounders. Different lag structures, polynomial distributed lag models, and two-pollutant models were examined. Under Lag01, in S/C de Tenerife, a 10 μg/m3 increase in PM2.5 and PM10–2.5 was associated with a 5.1 % risk increase (95 % confidence interval [CI] 1.0 to 9.2) in all respiratory and with a 7.7 % increase (95 % CI 0.9 to 14.9) in COPD emergency admissions, respectively. In L/P de Gran Canaria, a positive association between PM10–2.5, PM2.5, and NO2 with the increased risk of asthma hospitalization was found: 11.2 % (95 % CI 0.5 to 22.9), 21.9 % (95 % CI 6.9 to 39.0), and a 17.4 % (95 % CI 6.6 to 29.4), respectively. The overall findings suggest that in these cities, (1) PM2.5, PM10–2.5, and NO2 are associated with the risk of emergency hospital admission for respiratory diseases; (2) there is no evidence of confounding for the associations observed; and (3) PM10–2.5 may have an impact on public health.

Birth Weight, Gestational Age, Fetal Growth and Childhood Asthma Hospitalization.

Background: Childhood asthma may have a fetal origin through fetal growth and development of the immunocompetence or respiratory organs. Objective: We examined to which extent short gestational age, low birth weight and fetal growth restriction were associated with an increased risk of asthma hospitalization in childhood. Methods: We undertook a cohort study based on several national registers in Denmark, Sweden and Finland. We included all live singleton born children in Denmark during 1979-2005 (N = 1,538,093), in Sweden during 1973-2004 (N = 3,067,670), and a 90% random sample of singleton children born in Finland during 1987-2004 (N = 1,050,744). The children were followed from three years of age to first hospitalization for asthma, emigration, death, their 18th birthday, or the end of study (the end of 2008 in Denmark, and the end of 2007 in Sweden or Finland), whichever came first. We computed the pseudo-values for each observation and used them in a generalized estimating equation to estimate relative risks (RR) for asthma hospitalization. Results: A total of 131,783 children were hospitalized for asthma during follow-up. The risk for asthma hospitalization consistently increased with lower birth weight and shorter gestational age. A 1000-g decrease in birth weight corresponded to a RR of 1.17 (95% confidence interval (CI) 1.15-1.18). A one-week decrease in gestational age corresponded to a RR of 1.05 (95% CI 1.04-1.06). Small for gestational age was associated with an increased risk of asthma hospitalization in term but not in preterm born children. Conclusions: Fetal growth and gestational age may play a direct or indirect causal role in the development of childhood asthma.

Risk Of Hospitalization For Asthma Related To Extreme Temperature And Precipitation Events In Maryland

Introduction: Several studies have found associations between ambient temperature and overall precipitation with risk of respiratory health outcomes such as asthma. Limited understanding exists regarding exposure to extreme weather events and risk of hospitalization for asthma. Methods: Hospitalization records for all asthma cases (ICD-9 code 493) were obtained for the state of Maryland from 2002 to 2012 along with clinical and demographic information. Extreme temperature and precipitation events were defined as days when the daily maximum temperature or precipitation exceeded the 95th percentile of county and calendar day specific maximum daily temperature and precipitation over a 30-year baseline period (1960-1989). We used a time-stratified case-crossover design to examine the association between exposure to extreme events and risk of hospitalization for asthma. Results: From 2000 to 2012, 116,470 asthma hospitalizations occurred in Maryland. We observed a 3% increase in risk of hospitalization for asthma associated with 1 unit increase in extreme temperature events (Odds Ratios (OR) 1.03; 95% Confidence Interval (CI): 1.00-1.07), with a considerably higher risk associated with summertime extreme temperature events (OR 1.22, CI: 1.14-1.31). Furthermore, the increase in risk was more pronounced among African Americans compared to Whites. Likewise, summertime extreme precipitation event was associated with a 14 % increase in risk (OR 1.14, CI: 1.06 - 1.21). Discussion: Our results indicate that extreme temperature and precipitation events increase the risk of hospitalization for asthma. Further efforts are currently underway to assess how this risk varies across geographic areas and demographic characteristics.

The long-term programming effect of maternal 25-hydroxyvitamin D in pregnancy on allergic airway disease and lung function in offspring after 20 to 25 years of follow-up

High prenatal vitamin D status has been linked to decreased risk of atopic diseases in early childhood, but whether such relations persist until adulthood has not been explored. We sought to examine the association between maternal 25-hydryxovitamin D (25[OH]D) concentrations and outcomes of allergic airway disease and lung function in offspring with 20 to 25 years of follow-up. In a prospective birth cohort with 965 pregnant women enrolled in 1988-1989, maternal 25(OH)D concentrations were quantified in serum from gestational week 30 (n = 850 [88%]). Offspring were followed in nationwide registries with complete follow-up to the age of 25 years (n = 850 [100%]). Additionally, at age 20 years, outcomes of allergic airway disease and lung function were assessed in a subset of offspring by using blood samples and spirometry (n = 410 [45%]) and a questionnaire (n = 641 [70%]). Exposure to a high maternal 25(OH)D concentration (≥125 nmol/L) was associated with an increased risk of asthma hospitalizations in offspring (hazard ratio [HR], 1.81; 95% CI, 0.78-4.16) during 25 years of follow-up compared with the reference group (75-<125 nmol/L). Furthermore, there were lower risks of asthma hospitalizations (HR, 0.29; 95% CI, 0.08-1.02) and asthma medication use (HR, 0.58; 95% CI, 0.35-0.95) in those exposed to a low maternal 25(OH)D concentration (<50 nmol/L). In a reduced set of participants, we found no associations between maternal 25(OH)D concentrations and offspring allergen-specific IgE, total IgE, and eosinophil cationic protein levels; self-reported doctor's diagnosis of asthma or hay fever; or lung function at 20 years of age. Our study does not provide support for a protective effect of a high maternal 25(OH)D concentration on outcomes of allergic airway disease and lung function at 20 to 25 years of age. In contrast, a high maternal 25(OH)D concentration might be associated with an increased risk of allergic diseases in offspring.

Breast-feeding and hospitalization for asthma in early childhood: a nationwide longitudinal survey in Japan.

Whether or not breast-feeding is protective against asthma among children is still controversial. Therefore, we examined the effects of breast-feeding on hospitalization for asthma in early childhood. Secondary data analyses of a nationwide longitudinal survey of children in Japan ongoing since 2001, with results collected from 2001 to 2004. We used logistic regression models to evaluate the associations of breast-feeding with hospitalization for asthma in children between the ages of 6 and 42 months, adjusting for children's factors (sex, day-care attendance and presence of older siblings) and maternal factors (educational attainment and smoking habit). Setting All over Japan. Term singleton children with information on feeding practices during infancy (n 43367). After adjusting for maternal factors and children's factors, exclusive breast-feeding at 6-7 months of age was associated with decreased risk of hospitalization for asthma in children. The adjusted odds ratio was 0.77 (95% CI 0.56, 1.06). One-month longer duration of breast-feeding was associated with a 4% decreased risk of hospitalization for asthma (OR = 0.96; 95% CI 0.92, 0.99). The protective effects of breast-feeding on hospitalization for asthma were observed in children between the ages of 6 and 42 months.

Birth weight, gestational age, fetal growth and childhood asthma hospitalization

BackgroundChildhood asthma may have a fetal origin through fetal growth and development of the immunocompetence or respiratory organs.ObjectiveWe examined to which extent short gestational age, low birth weight and fetal growth restriction were associated with an increased risk of asthma hospitalization in childhood.MethodsWe undertook a cohort study based on several national registers in Denmark, Sweden and Finland. We included all live singleton born children in Denmark during 1979-2005 (N = 1,538,093), in Sweden during 1973-2004 (N = 3,067,670), and a 90% random sample of singleton children born in Finland during 1987-2004 (N = 1,050,744). The children were followed from three years of age to first hospitalization for asthma, emigration, death, their 18th birthday, or the end of study (the end of 2008 in Denmark, and the end of 2007 in Sweden or Finland), whichever came first. We computed the pseudo-values for each observation and used them in a generalized estimating equation to estimate relative risks (RR) for asthma hospitalization.ResultsA total of 131,783 children were hospitalized for asthma during follow-up. The risk for asthma hospitalization consistently increased with lower birth weight and shorter gestational age. A 1000-g decrease in birth weight corresponded to a RR of 1.17 (95% confidence interval (CI) 1.15-1.18). A one-week decrease in gestational age corresponded to a RR of 1.05 (95% CI 1.04-1.06). Small for gestational age was associated with an increased risk of asthma hospitalization in term but not in preterm born children.ConclusionsFetal growth and gestational age may play a direct or indirect causal role in the development of childhood asthma.

Empirical validation of the “Pediatric Asthma Hospitalization Rate” indicator

BackgroundQuality assessment in pediatric care has recently gained momentum. Although many of the approaches to indicator development are similar regardless of the population of interest, few nationwide sets of indicators specifically designed for assessment of primary care of children exist. We performed an empirical analysis of the validity of “Pediatric Asthma Hospitalization Rate” indicator under the assumption that lower admission rates are associated with better performance of primary health care.MethodsThe validity of “Pediatric Asthma Hospitalization Rate” indicator proposed by the Agency for Healthcare Research and Quality in the Italian context was investigated with a focus on selection of diagnostic codes, hospitalization type, and risk adjustment. Seasonality and regional variability of hospitalization rates for asthma were analyzed for Italian children aged 2–17 years discharged between January 1, 2009, and December 31, 2011 using the hospital discharge records database. Specific rates were computed for age classes: 2–4, 5–9, 10–14, 15–17 years.ResultsIn the years 2009–2011 the number of pediatric hospitalizations for asthma was 14,389 (average annual rate: 0.52 per 1,000) with a large variability across regions. In children aged 2–4 years, the risk of hospitalization for asthma was 14 times higher than in adolescents, then it dropped to 4 in 5- to 9-year-olds and to 1.1 in 10- to 14-year-olds. The inclusion of diagnoses of bronchitis revealed that asthma and bronchitis are equally represented as causes of hospital admissions and have a similar seasonality in preschool children, while older age groups experience hospital admissions mainly in spring and fall, this pattern being consistent with a diagnosis of atopic asthma. Rates of day hospital admissions for asthma were up to 5 times higher than the national average in Liguria and some Southern regions, and close to zero in some Northern regions.ConclusionsThe patterns of hospitalization for pediatric asthma in Italy showed that at least two different indicators are needed to measure accurately the quality of care provided to children. The candidate indicators should also include day hospital admissions to better assess accessibility. Future evaluation by a structured clinical panel review at the national level might be helpful to refine indicator definitions and risk groupings, to determine appropriate application for such measures, and to make recommendations to policy makers.

Psychological Stress and Hospitalization for Childhood Asthma-a Nationwide Cohort Study in Two Nordic Countries

ObjectiveExposures to psychological stress in early life may contribute to the development or exacerbation of asthma. We undertook a cohort study based on data from several population-based registers in Denmark and Sweden to examine whether bereavement in childhood led to increased asthma hospitalization.MethodsAll singleton children born in Denmark during 1977-2008 and in Sweden during 1973-2006 were included in the study (N=5,202,576). The children were followed from birth to the date of first asthma hospitalization, emigration, death, their 18th birthday, or the end of study (31 December 2007 in Sweden and 31 December 2008 in Denmark), whichever came first. All the children were assigned to the non-bereaved group until they lost a close relative (mother, father or a sibling), from when they were included in the bereaved group. We evaluated the hazard ratio (HR) of first hospitalization for asthma in bereaved children using Cox proportional hazards regression models, compared to those who were in the non-bereaved group. We also did a sub-analysis on the association between bereavement and first asthma medication.ResultsA total of 147,829 children were hospitalized for asthma. The overall adjusted HR of asthma hospitalization in bereaved children was 1.10 (95% confidence interval (CI): 1.04-1.16), compared to non-bereaved children. The risk of asthma hospitalization was increased in those who lost a close relative at age of 14-17 years (HR=1.54, 95% CI: 1.23-1.92), but not in younger age groups. The association between bereavement and asthma hospitalization did not change over time since bereavement. In the sub-analysis in singleton live births during 1996-2008 recorded in the DMBR, bereavement was associated with a lower use of asthma medication (HR=0.87, 95% CI: 0.80-0.95).ConclusionsOur data suggests that psychological stress following bereavement in late adolescence is associated with an increased risk of asthma hospitalization or lowers the threshold for asthma hospitalization.

Statins in the treatment of asthma

Current evidence on statin agents as potential alternatives or adjuncts to corticosteroid therapy for asthma is reviewed. Research showing antiinflammatory and antioxidant effects of statins in animal models suggested that the cholesterol-lowering drugs might be useful in mitigating the adverse effects of long-term corticosteroid therapy in patients with asthma, but studies in humans have yielded mixed results. Two small placebo-controlled clinical trials indicated that statins were not effective in combating asthmatic inflammatory processes, and trials of statins as adjunctive therapy have indicated minimal steroid-sparing benefits. In two studies involving a total of more than 1000 current and former smokers with asthma, statin use correlated with reduced acute asthma exacerbations and a slower decline of lung function in some patients. A large population-based study (n = 3965) found that statin therapy was associated with a significantly reduced risk of hospitalization for asthma after an average follow-up period of about 4.5 years; a smaller U.S. retrospective cohort study indicated a significantly lower 1-year rate of asthma-related emergency room visits among patients receiving statins relative to those not using statins (9.08% versus 4.18%). Much of the research on statins and asthma has not controlled for confounding influences such as patient comorbidities and concomitant medication use. Clinical trials have shown that statin therapy is not superior to and does not enhance the beneficial effects of inhaled corticosteroids for the treatment of asthma. Some evidence suggests that statins may help preserve lung function in cigarette smokers with obstructive pulmonary disease and reduce hospitalizations in asthmatic smokers and nonsmokers.

Use of Antibiotics During Pregnancy Increases the Risk of Asthma in Early Childhood

To investigate whether maternal use of antibiotics during pregnancy influences the development of asthma and eczema early in life.The Copenhagen Prospective Study on Asthma in Childhood (COPSAC), a birth cohort of 411 infants born between 1998 and 2001 to mothers with a history of asthma. The COPSAC data were supplemented by data from the Danish National Birth Cohort (DNBC) consisting of 101 042 pregnant women and their children recruited between 1997 and 2003. Both cohorts were followed prospectively for 5 years.History of maternal exposure to antibiotics in the third trimester was obtained during the first COPSAC enrollment visit. Asthma exacerbations were defined as need for oral prednisolone, high-dose inhaled corticosteroids (ICS), or asthma hospitalization. In the DNBC data, investigators defined maternal antibiotic use as at least 1 filled antibiotic prescription during pregnancy. Asthma was defined as either an asthma hospitalization or an ICS prescription filled at least once.In the COPSAC birth cohort, children of mothers who used antibiotics during the third trimester were at a significantly increased risk of developing early asthma exacerbation (hazard ratio [HR]: 1.98). Maternal use of antibiotics in the third trimester did not influence the child’s risk of eczema. An increased risk of asthma after maternal antibiotic exposure was confirmed via DNBC analysis: children of mothers exposed to antibiotics during pregnancy were at a higher risk of asthma hospitalization (HR: 1.17) and ICS use (HR: 1.18). For each additional antibiotic prescription filled during pregnancy, a progressively increased risk of asthma was demonstrated (adjusted P = .01).An increased risk of asthma was found in a prospectively followed cohort of children whose mothers received antibiotics during the third trimester of pregnancy. This finding was confirmed in an unselected national birth cohort of mothers. No increased risk of eczema was detected in either cohort.Perturbing the native microbiome in the lungs has been increasingly shown to affect both asthma development and clinical control. This study adds to the mounting evidence suggesting that changing the balance between beneficial and pathogenic bacteria may play a role in the development of asthma. In a prospective analysis, these investigators implicate in utero exposure to maternal antibiotics as a significant risk factor in early asthma pathogenesis.

Non-anthropogenic Dust exposure and Asthma Symptoms in Children

Background:Studies have shown a positive association between air pollutants and asthma in children. The Negev desert (Israel) is frequently subjected to dust storms (DS) originating from arid soils. The evidence regarding the association with non-anthropogenic PM due to DS is limited. Aims:To assess the impact of DS on asthma/wheezing hospitalizations and asthma medications utilization. Methods:We identified children admitted to Soroka University Medical Center (SUMC, serving a population of 261,600 children in Negev) during 2001-2011 with asthma or wheezing. Meteorological and air-pollution data were obtained. An air-polluted day was defined as a day with a PM10 concentration two standard deviations above the background. We used a case crossover analysis with conditional logistic regression for hospitalizations and time series analysis (GLM and GAM models) for asthma medications purchase assessments. Results:3,481 children were admitted (5,304 hospitalizations), 62% were males and 52.5% under two years. The average admissions number was 1.04/day, with higher incidence during the winter season (1.5/day). The number of DS days was 461 (12%). DS increased the risk for the same day hospitalization by 1.09 (95%CI 0.99-1.20, P=0.08), adjusted for seasonality, temperature, relative humidity and SO2. Exclusion of children with respiratory infections did not change the inference. In the spring-summer the association was stronger (odds ratio [OR]=1.43, 95%CI 1.42-1.72, P=0.01). In analysis by ethnicity, the positive significant effect was shown only among Bedouin Arabs (OR=1.93, 95%CI 1.04-1.35, P=0.008). Asthma medications purchase was 15% higher in DS days (95%CI 17-23%, P&lt;0.01). Conclusion:The high PM10 levels during DS days increase the risk for asthma hospitalizations and purchasing of asthma medications among children, mostly in the spring and summer seasons. Bedouin children are at greater risk, partially due to residing in non-permanent dwelling conditions.

Short-term risk of hospitalization for asthma or bronchiolitis in children living near an aluminum smelter

Few studies have measured the effect of short-term exposure to industrial emissions on the respiratory health of children. Here we estimate the risk of hospitalization for asthma and bronchiolitis in young children associated with their recent exposure to emissions from an aluminum smelter. We used a case–crossover design to assess the risk of hospitalization, February 1999–December 2008, in relation to short-term variation in levels of exposure among children 0–4 years old living less than 7.5 km from the smelter. The percentage of hours per day that the residence of a hospitalized child was in the shadow of winds crossing the smelter was used to estimate the effect of wind-borne emissions on case and crossover days. Community-wide pollutant exposure was estimated through daily mean and daily maximum SO2 and PM2.5 concentrations measured at a fixed monitoring site near the smelter. Odds ratios (OR) were estimated using conditional logistic regressions. The risk of same-day hospitalization for asthma or bronchiolitis increased with the percentage of hours in a day that a child's residence was downwind of the smelter. For children aged 2–4 years, the OR was 1.27 (95% CI=1.03–1.56; n=103 hospitalizations), for an interquartile range (IQR) of 21% of hours being downwind. In this age group, the OR with PM2.5 daily mean levels was slightly smaller than with the hours downwind (OR: 1.22 for an IQR of 15.7 μg/m3, 95% CI=1.03–1.44; n=94 hospitalizations). Trends were observed between hospitalizations and levels of SO2 for children 2–4 years old. Increasing short-term exposure to emissions from a Quebec aluminum smelter was associated with an increased risk of hospitalization for asthma and bronchiolitis in young children who live nearby. Estimating exposure through records of wind direction allows for the integration of exposure to all pollutants carried from the smelter stack.

Pollen exposure in pregnancy and infancy and risk of asthma hospitalisation - a register based cohort study

BackgroundA seasonal effect of month of birth and risk of allergic disease has been suggested by numerous studies. Few studies have directly measured pollen exposures at different points during pregnancy and in early life, and assessed their effects on risk of respiratory disease outcomes.MethodsPollen exposure was calculated for the first and last 12 weeks of pregnancy and the first 12 weeks of infancy for all children conceived by women residing in Stockholm, Sweden, between 1988 and 1995. Hospital admission data for respiratory conditions in the first year of life was also collected.ResultsOut of 110,381 children, 940 had been hospitalised for asthma by 12-months of age. Pollen levels showed both marked seasonal variations and between year differences. Exposure to high levels of pollen in the last 12 weeks of pregnancy was associated with an increased risk of asthma hospitalisation (aOR = 1.35, 95% CI = 1.07-1.71 for highest quartile versus remaining infants). Exposure to high levels of pollen in the first three months of life was associated with a reduced risk (aOR = 0.76, 95% CI = 0.59-0.98) but only in children of heavy smoking mothers.ConclusionsHigh levels of pollen exposure during late pregnancy were somewhat unexpectedly associated with an elevated risk of hospitalisation for asthma within the first year of life.

Use of Antibiotics during Pregnancy Increases the Risk of Asthma in Early Childhood

To investigate the hypothesis that mother's use of antibiotics in pregnancy could influence asthma and eczema in early life. Subjects were included from the Copenhagen Prospective Study on Asthma in Childhood cohort of children born of mothers with asthma (N=411). Severe asthma exacerbations and eczema were diagnosed by research unit physicians. Replication was sought in children from the Danish National Birth Cohort (N=30 675). Asthma outcomes were hospitalization and use of inhaled corticosteroids. Eczema was defined by an algorithm developed from cases of clinically verified eczema. All children were followed to age 5 years in a cohort study design. The Copenhagen Prospective Study on Asthma in Childhood data showed increased risk of asthma exacerbation (hazard ratio 1.98 [95% CI 1.08-3.63]) if mothers had used antibiotics during third trimester. The Danish National Birth Cohort confirmed increased risk of asthma hospitalization (hazard ratio 1.17 [1.00-1.36]), and inhaled corticosteroids (1.18 [1.10-1.27]) in the children if mothers used antibiotics any time during pregnancy. In the subgroup of mothers using antibiotics for nonrespiratory infection, the children also had increased risk of asthma. We found increased risk of asthma associated with maternal antibiotic use in a clinical study of a birth cohort with increased risk of asthma and replicated this finding in an unselected national birth cohort, and in a subgroup using antibiotics for nonrespiratory infections. This supports a role for bacterial ecology in pre- or perinatal life for the development of asthma.

Prenatal Stress and Risk of Asthma Hospitalization in the Offspring

Recent research suggested that maternal stress and anxiety increase the risk of asthma and eczema in the offspring. In this study, we aimed to study whether maternal exposure to death of a spouse or a child is associated with risk of asthma hospitalization in the offspring using a very large population-based cohort. In a cohort of 3.2 million births in Sweden between January 1, 1973, and December 31, 2004, mothers were considered exposed if their spouse or child died up to 6 months before or during pregnancy. Offspring were followed up from birth to their death, migration, first hospitalization with asthma, or December 31, 2006, whichever came first; hospital admissions were identified by linkage of several national Swedish registers. Log-linear Poisson regression was used for data analysis. Overall, the risk of offspring asthma was increased with any prenatal exposure to bereavement in any exposure period (adjusted relative risk [RR] = 1.20 [95% confidence interval {CI} = 1.03-1.39]). The risk was higher when the exposure period was restricted to pregnancy only (adjusted RR = 1.43 [95% CI = 1.06-1.92]). Furthermore, the risk of asthma was increased in relation to death of a spouse during pregnancy (adjusted RR = 1.59 [95% CI = 1.10-2.30]). These findings suggest that prenatal exposure to severe life events increases the risk of hospitalization for asthma in the offspring. Fetal programming may be a plausible explanation for the association.

Asma e poluentes ambientais: um estudo de séries temporais

To estimate the risk of hospitalization for asthma in children after exposure to air pollutants in a medium-sized city in Southeast Brazil. An ecological time series study was carried out with hospitalization data for asthma in children under 10 years of age living in São José dos Campos, SP, Brazil, and concentrations of particulate matter with aerodynamic diameter < 10 microns, sulfur dioxide, and ozone; data were also obtained on relative humidity and temperatures. Pearson's coefficient correlation was used for the study variables. To estimate the association between hospitalizations due to asthma and air pollutants, Poisson regression generalized additive models were built, according to lags of up to seven days. There was a strong correlation between hospitalizations and the pollutants particulate matter and sulfur dioxide. Exposure to particulate matter and sulfur dioxide were associated with significant relative risks of 1.01 to 1.04 of hospitalization due to asthma on the same day and within three days after exposure. Increases in the concentrations of these pollutants increase the risk of hospitalization between 8% and 19%. There is evidence of the effect of air pollutants on asthma hospitalization in a medium-sized city in Southeast Brazil.