Effect of vitamin D supplementation on total and allergen-specific IgE in children with asthma and low vitamin D levels.

BACKGROUND: Observational studies have yielded inconsistent findings for the relation between vitamin D level and total IgE or allergic sensitization. OBJECTIVE: To determine whether vitamin D supplementation reduces levels of total IgE and IgE to each of 2 common indoor allergens in children with asthma and low vitamin D levels. METHODS: Total IgE, IgE to Dermatophagoides pteronyssinus, and IgE to Blattella germanica were measured at the randomization and exit visits for 174 participants in the Vitamin D Kids Asthma Study, a multicenter, double-blind, randomized placebo-controlled trial of vitamin D3 supplementation (4000 IU/d) to prevent severe exacerbations in children with persistent asthma and vitamin D levels less than 30 ng/mL. Multivariable linear regression was used for the analysis of the effect of vitamin D supplementation on change in each IgE measure. RESULTS: Participants were followed for an average of 316 days. At the exit visit, more subjects in the vitamin D arm achieved a vitamin D level equal to or more than 30 ng/mL compared with those in the placebo arm (87% vs 30%; P < .001). In a multivariable analysis, vitamin D3 supplementation had no significant effect on change in total IgE, IgE to Dermatophagoides pteronyssinus, or IgE to Blattella germanica between the exit and randomization visits (eg, for log10 total IgE, ß = 0.007; 95% CI, -0.061 to 0.074; P = .85). CONCLUSIONS: Vitamin D supplementation, compared with placebo, has no significant effect on serum levels of total IgE, IgE to dust mite, or IgE to cockroach in children with asthma and low vitamin D levels.

Phenotypes of Recurrent Wheezing in Preschool Children: Identification by Latent Class Analysis and Utility in Prediction of Future Exacerbation.

BACKGROUND: Recurrent preschool wheezing is a heterogeneous disorder with significant morbidity, yet little is known about phenotypic determinants and their impact on clinical outcomes. OBJECTIVE: Latent class analysis (LCA) was used to identify latent classes of recurrent preschool wheeze and their association with future exacerbations and inhaled corticosteroid (ICS) treatment response. METHODS: Data from 5 clinical trials of 1708 children aged 12 to 71 months with recurrent wheezing were merged. LCA was performed on 10 demographic, exposure, and sensitization variables to determine the optimal number of latent classes. The primary outcome was the annualized rate of wheezing exacerbations requiring systemic corticosteroids during the study intervention period; the secondary outcome was the time to first exacerbation. Exploratory analyses examined the effect of daily ICS treatment on exacerbation outcomes. RESULTS: Four latent classes of recurrent wheezing were identified; these were not distinguished by current symptoms or historical exacerbations but differed with regard to allergen sensitization and/or exposures. Annualized exacerbation rates (mean ± SEM/year) were 0.65 ± 0.06 for class 1 ("minimal sensitization"), 0.93 ± 0.10 for class 2 ("sensitization with indoor pet exposure"), 0.60 ± 0.07 for class 3 ("sensitization with tobacco smoke exposure"), and 0.81 ± 0.10 for class 4 ("multiple sensitization and eczema") (P < .001). In a research setting of high adherence, daily ICS treatment improved exacerbation rates in classes 2 and 4 but not the other groups. CONCLUSIONS: Sensitization and exposure assessments are useful in the prediction of future exacerbation and may identify children most likely to respond favorably to daily ICS treatment.

Medical and Social Determinants of Health Associated with Intensive Care Admission for Asthma in Children.

RATIONALE: Risk factors for severe asthma exacerbations in children requiring admission to the intensive care unit (ICU) may occur in variety of medical, environmental, economic, and socioeconomic domains. OBJECTIVES: We sought to characterize medical and sociodemographic risk factors among children who required admission to the intensive care unit for asthma. METHODS: Data were obtained from the Greater Cincinnati Asthma Risk Study, a population-based, prospective, observational cohort of children admitted for treatment of acute asthma or bronchodilator-responsive wheezing. Data collected on 774 children included race, socioeconomic status, allergen sensitization, environmental exposures, psychosocial strain, and financial hardship. Analyses compared children admitted to the ICU to those admitted to a medical inpatient unit. MEASUREMENTS AND MAIN RESULTS: One hundred sixty-one (20.9%) children required admission to intensive care. There was no difference in sex, race, insurance status, caregiver educational level, income, financial strain, psychological distress, or marital status between the ICU and non-ICU cohorts. Risk for medication nonadherence assessed by parent report was not different between groups. Although previous hospital admission or emergency department visit history did not differ between the groups, prior ICU admission was more common among those admitted to the ICU at the index admission (27 vs. 16%, P = 0.002). Children requiring intensive care admission were more likely to be sensitized to multiple aeroallergens. Exposure to cigarette smoke (measured as salivary cotinine), although a risk factor for hospital admission, was negatively associated with risk of ICU admission. CONCLUSIONS: Social and economic risk factors typically predictive of increased asthma morbidity, including exposure to tobacco smoke, were not associated with ICU admission among a population of children admitted to the hospital for treatment of acute asthma. Intrinsic disease factors, including allergic sensitization, may be more important predictors of ICU admission.

Increased Dose of Inhaled Corticosteroid versus Add-On Long-acting ß-Agonist for Step-Up Therapy in Asthma.

RATIONALE: Guidelines advocate adding long-acting ß-agonist (LABA) to inhaled corticosteroid as the preferred step-up therapy to increasing inhaled corticosteroid dose for patients with uncontrolled asthma on inhaled corticosteroid monotherapy. However, less than 5% of patients with asthma qualify for the randomized controlled trials on which guidelines are based. Thus, real-world data are needed to complement the results of randomized trials with narrow entry criteria. OBJECTIVES: To compare the effectiveness of stepping up asthma therapy with an increased dose of various types of inhaled corticosteroid as compared with add-on LABA. METHODS: We performed a historical matched cohort study using large primary care databases to compare asthma step-up therapy with small- and standard size-particle inhaled corticosteroid versus added LABA for patients 12-80 years old. As outcomes, we examined a composite of asthma control and rates of severe exacerbations. MEASUREMENTS AND MAIN RESULTS: The odds of asthma control and rates of severe exacerbations over one outcome year were comparable with increased inhaled corticosteroid dose versus added LABA. The adjusted odds ratios (95% confidence interval) for achieving asthma control with increased inhaled corticosteroid dose versus inhaled corticosteroid/LABA were 0.99 (0.88-1.12) for small-particle inhaled corticosteroid (n = 3,036 per cohort) and 0.85 (0.67-1.07) for standard size-particle inhaled corticosteroid (n = 809 per cohort). The adjusted rate ratios (95% confidence interval) for severe exacerbations, compared with inhaled corticosteroid/LABA combination inhaler, were 1.04 (0.91-1.20) and 1.18 (0.92-1.54), respectively. The results were not affected by smoking status. CONCLUSIONS: When applied to a broad primary care population, antiinflammatory therapy using increased doses of small- or standard size-particle inhaled corticosteroid is as effective as adding LABA, as measured by outcomes important to both patients and providers. Real-world populations and outcomes need to be taken into consideration when formulating treatment recommendations.

Predictors of asthma control and lung function responsiveness to step 3 therapy in children with uncontrolled asthma.

BACKGROUND: Predictors of improvement in asthma control and lung function to step 3 therapy in children with persistent asthma have not been identified despite reported heterogeneity in responsiveness. OBJECTIVE: We sought to evaluate potential predictors of asthma control and lung function responsiveness to step 3 therapy. METHODS: A post hoc analysis from the Best Add-On Giving Effective Response (BADGER) study tested the association between baseline biological, asthma control, pulmonary function, and demographic markers and responsiveness to step-up to a higher dose of inhaled corticosteroid (ICS step-up therapy) or addition of leukotriene receptor antagonist (LTRA step-up therapy) or long-acting ß2-agonist (LABA step-up therapy). RESULTS: In multivariate analyses higher impulse oscillometry reactance area was associated (P = .048) with a differential FEV1 response favoring LABA over ICS step-up therapy, whereas higher urinary leukotriene E4 levels were marginally (P = .053) related to a differential FEV1 response favoring LTRA over LABA step-up therapy. Predictors of differential responses comparing ICS with LTRA step-up therapy were not apparent, probably because of suppression of allergic markers with low-dose ICS treatment. Minimal overlap was seen across FEV1 and asthma control day predictors, suggesting distinct mechanisms related to lung function and asthma control day responses. CONCLUSION: Levels of impulse oscillometry reactance area indicating peripheral airway obstruction and urinary leukotriene E4 levels indicating cysteinyl leukotriene inflammation can differentiate LABA step-up responses from responses to LTRA or ICS step-up therapy. Further studies with physiologic, genetic, and biological markers related to these phenotypes will be needed to predict individual responses to LABA step-up therapy.