Carol J. Blaisdell

Asthma outcomes: Exacerbations

BACKGROUNDnThe goals of asthma treatment include preventing recurrent exacerbations. Yet there is no consensus about the terminology for describing or defining exacerbation or about how to characterize an episodes severity.nnnOBJECTIVEnNational Institutes of Health institutes and other federal agencies convened an expert group to propose how asthma exacerbation should be assessed as a standardized asthma outcome in future asthma clinical research studies.nnnMETHODSnWe used comprehensive literature reviews and expert opinion to compile a list of asthma exacerbation outcomes and classified them as either core (required in future studies), supplemental (used according to study aims and standardized), or emerging (requiring validation and standardization). This work was discussed at a National Institutes of Health-organized workshop in March 2010 and finalized in September 2011.nnnRESULTSnNo dominant definition of exacerbation was found. The most widely used definitions included 3 components, all related to treatment, rather than symptoms: (1) systemic use of corticosteroids, (2) asthma-specific emergency department visits or hospitalizations, and (3) use of short-acting β-agonists as quick-relief (sometimes referred to as rescue or reliever) medications.nnnCONCLUSIONSnThe working group participants propose that the definition of asthma exacerbation be a worsening of asthma requiring the use of systemic corticosteroids to prevent a serious outcome. As core outcomes, they propose inclusion and separate reporting of several essential variables of an exacerbation. Furthermore, they propose the development of a standardized, component-based definition of exacerbation with clear thresholds of severity for each component.

Environmental allergens and asthma in urban elementary schools

BACKGROUNDnAsthma in school children is rising, and indoor allergens are very common triggers of asthma attacks; however, the risk of the school environment on asthma has not been well studied.nnnOBJECTIVEnTo determine the presence and the levels of common aeroallergens in schools, where asthma prevalence rates are high.nnnMETHODSnSettled dust samples were collected from 12 Baltimore City public elementary schools, and they were analyzed for the following allergens: cockroaches (Bla g 1/2), dust mites (Der f 1/p 1), dog (Can f 1), cat (Fel d 1), and mouse (Mus m 1). School asthma prevalence rates were correlated with allergen levels, and association between allergen levels and other risk factors present in the schools environment was examined.nnnRESULTSnThe mean and range levels were 1.49 U/g (0 to 8) for Bla g 1/2; 0.38 microg/g (0 to 11.9) for the Der f 1/p 1; 1.44 microg/g (0.1 to 9.6) for Can f 1; 1.66 microg/g (0.2 to 12) for Fel d 1; and 6.24 microg/g (0.3 to 118.3) for Mus m 1. Dust mite, cat and dog allergens were significantly in rooms with carpet and/or area rugs, compared to rooms with bare floors (P < 0.05). Asthma prevalence rates varied from 11.8 to 20.8% between schools and positively correlation with the mean levels of Bla g 1/2 in the schools (P = 0.001).nnnCONCLUSIONSnCommon allergens that are known to trigger asthma were detected in all school environments, where asthma prevalence rates were high. However, the overall allergen levels were low, indicating that other factors, including exposures in the homes of asthmatic patients, may have more relevance to sensitization and symptoms than school exposures.

Elevated ambient air zinc increases pediatric asthma morbidity.

Background Recent studies indicate that the composition of fine particulate matter [PM ≤ 2.5 μm in aerodynamic diameter (PM2.5)] is associated with increased hospitalizations for cardiovascular and respiratory diseases. The metal composition of PM2.5 influences allergic and/or inflammatory reactions, and ambient zinc contributes to worsening pulmonary function in susceptible adults. However, information is limited concerning associations between ambient air zinc levels and health care utilization for asthma, especially among children. Objective We aimed to investigate the relationship between outdoor ambient air PM2.5 zinc levels and urgent health care utilization for children living in an urban area. Methods We used a time-series study to estimate the association of ambient air PM2.5 zinc levels with hospital admissions and emergency department (ED) utilization by children in Baltimore, Maryland, controlling for time trends. We used data from daily discharge administrative claims of ED and hospital utilization for asthma in children, 0–17 years of age for Greater Baltimore from June 2002 through November 2002. We collected ambient air PM2.5 metal concentration data, determined by X-ray fluorescence spectroscopy, during the U.S. Environmental Protection Agency–sponsored Baltimore Supersite project. Results Previous-day medium levels of zinc (8.63–20.76 ng/m3) are associated with risks of pediatric asthma exacerbations that are 1.23 (95% confidence interval, 1.07–1.41) times higher than those with previous-day low levels of zinc (< 8.63 ng/m3) after accounting for time-varying potential confounders. Conclusion Results suggest that high ambient air PM2.5 zinc levels are associated with an increase in ED visits/hospital admissions for asthma on the following day among children living in an urban area.

Temporal dynamics of emergency department and hospital admissions of pediatric asthmatics

Asthma is a chronic disease that can result in exacerbations leading to urgent care in emergency departments (EDs) and hospitals. We examined seasonal and temporal trends in pediatric asthma ED (1997-1999) and hospital (1986-1999) admission data so as to identify periods of increased risk of urgent care by age group, gender, and race. All pediatric ED and hospital admission data for Maryland residents occurring within the state of Maryland were evaluated. Distinct peaks in pediatric ED and hospital asthma admissions occurred each year during the winter-spring and autumn seasons. Although the number and timing of these peaks were consistent across age and racial groups, the magnitude of the peaks differed by age and race. The same number, timing, and relative magnitude of the major peaks in asthma admissions occurred statewide, implying that the variables affecting these seasonal patterns of acute asthma exacerbations occur statewide. Similar gross seasonal trends are observed worldwide. Although several environmental, infectious, and psychosocial factors have been linked with increases in asthma exacerbations among children, thus far they have not explained these seasonal patterns of admissions. The striking temporal patterns of pediatric asthma admissions within Maryland, as described here, provide valuable information in the search for causes.

Obstructive sleep apnea and history of asthma in snoring children.

Asthma has been identified as a possible risk factor for Obstructive Sleep Apnea (OSA) in children. It is not known whether parent-reported asthma increases the likelihood of the diagnosis of OSA in snoring children. We hypothesized that snoring children with asthma are more likely to have OSA than snoring children without asthma. This study is a 1-year retrospective review of polysomnogram and questionnaire data collected on 236 patients referred to the University of Maryland Pediatric Sleep laboratory for evaluation of snoring. Of the 236 patients, 58% (137/236) were boys, and 79% (173/219 reporting race) were African-American (AA). The age at referral was 7.2u2009±u20093.7xa0years (meanu2009±u2009S.D.). Mean body mass index (BMI) percentile was 73.4u2009±u200932.3%, with 43.2% (54/125) >95th percentile. A history of asthma was reported by 31.4% (74/236); no subject was symptomatic on the night of the study. We found no increased risk for polysomnographically diagnosed OSA for asthmatics. To the contrary, by logistic regression analysis, a parent/guardian report of asthma decreased the odds of having OSA by 34% (pu2009=u20090.027), controlling for individual and socioeconomic factors and assessment results. Polysomnographic (PSG) differences between asthmatic and non-asthmatic children were found in only the arousal index (11.0 vs.9.3u2009±u20096.5/h, pu2009=u20090.099) and total sleep time (337.1u2009±u200964.3 vs. 347u2009±u200965.2 min, pu2009=u20090.1) In a referral-based group of predominantly AA inner-city snoring children, asymptomatic asthma decreased the likelihood of OSA.

Relationships between pediatric asthma and socioeconomic/urban variables in Baltimore, Maryland

Spatial relationships between clinical data for pediatric asthmatics (hospital and emergency department utilization rates), and socioeconomic and urban characteristics in Baltimore City were analyzed with the aim of identifying factors that contribute to increased asthma rates. Socioeconomic variables and urban characteristics derived from satellite data explained 95% of the spatial variation in hospital rates. The proportion of families headed by a single female was the most important variable accounting for 89% of the spatial variation. Evidence suggests that the high rates of hospital admissions and emergency department (ED) visits may partially be due to the difficulty of single parents with limited resources managing their childs asthma condition properly. This knowledge can be used for education towards mitigating ED and hospital events in Baltimore City.

CLC-2 single nucleotide polymorphisms (SNPs) as potential modifiers of cystic fibrosis disease severity

BackgroundCystic fibrosis (CF) lung disease manifest by impaired chloride secretion leads to eventual respiratory failure. Candidate genes that may modify CF lung disease severity include alternative chloride channels. The objectives of this study are to identify single nucleotide polymorphisms (SNPs) in the airway epithelial chloride channel, CLC-2, and correlate these polymorphisms with CF lung disease.MethodsThe CLC-2 promoter, intron 1 and exon 20 were examined for SNPs in adult CF dF508/dF508 homozygotes with mild and severe lung disease (forced expiratory volume at one second (FEV1) > 70% and < 40%).ResultsPCR amplification of genomic CLC-2 and sequence analysis revealed 1 polymorphism in the hClC -2 promoter, 4 in intron 1, and none in exon 20. Fishers analysis within this data set, did not demonstrate a significant relationship between the severity of lung disease and SNPs in the CLC-2 gene.ConclusionsCLC-2 is not a key modifier gene of CF lung phenotype. Further studies evaluating other phenotypes associated with CF may be useful in the future to assess the ability of CLC-2 to modify CF disease severity.

Looking Beyond Urban/Rural Differences: Emergency Department Utilization by Asthmatic Children

Asthma causes pediatric morbidity throughout the US with substantial regional variability. Emergency department (ED) utilization data were studied to determine if geographic variability of pediatric asthma cases exists within a state. Records for non-neonatal Maryland children less than 18 years of age seen and discharged from Maryland EDs from April 1997 through March 2001 were analyzed. While Baltimore City had the highest rates of asthma visits, adjusted odds ratios identified the wealthiest suburban county to have a higher risk of an asthma ED visit. Children from rural counties, for the most part, had fewer ED asthma visits than children from urban and suburban counties.

Sleep architecture and behavioral abnormalities in children and adolescents.

OBJECTIVEnTo investigate the association between sleep disordered breathing (SDB) and parent report of attention and behavioral problems in children, as well as the association between sleep stage duration and measures of child functioning in a clinically referred sample.nnnMETHODSnA chart review was conducted of 95 children with clinical history of SDB who completed an overnight polysomnography study in a pediatric sleep laboratory. Child functioning was assessed at the time of the sleep study by parent report on the Child Behavior Checklist (CBCL). The apnea hypopnea index was used as a measure of SDB severity.nnnRESULTSnThe apnea hypopnea index was associated with externalizing behavior, but not attention problems on the CBCL. In children 2-3 years old, stage 4 sleep duration was associated with externalizing behavior. In children 4-16 years old, REM sleep duration was associated with externalizing behavior.nnnCONCLUSIONSnChildren with increased SDB severity may be at greater risk for behavioral problems. Differences between the association of sleep stages and externalizing behavior in toddlers compared with older children suggests possible developmental differences in the association between sleep and behavior.

Transition to Managed Care Impacts Health Care Service Utilization by Children Insured by Medicaid

Purpose. To evaluate the impact of transition to managed care from fee for service on asthma service utilization among Maryland Medicaid insured children. Methods. Healthcare claims from 1997–2000 for children with asthma insured by Maryland Medicaid were extracted and analyzed. Results. Between 1997–2000, inhaled corticosteroid use increased as a proportion of all asthma medications. Outpatient asthma visits increased from 4.2% to 5.9% of all outpatient claims as both asthma-related hospitalizations and emergency department visits decreased. Conclusions. Restructuring of Maryland Medicaid for children from fee for service to managed care was associated with improvement in asthma-related healthcare utilization claims.