Associations between family history of asthma, bronchopulmonary dysplasia, and childhood asthma in very low birth weight children

Risk of asthma in preterm infants with bronchopulmonary dysplasia: a systematic review and meta-analysis

BACKGROUND

This study aimed to systematically review and meta-analyze the available literature on the association between preterm infant bronchopulmonary dysplasia (BPD) and pre-adulthood asthma.

METHODS

Studies examining the association between BPD and asthma in children and adolescents were systematically reviewed, and a meta-analysis was conducted. We searched Scopus, Embase, Web of Science, PubMed, and Cochrane Library from the database inception to March 26, 2022. The pooled odds ratio (OR) estimate was used in our meta-analysis to calculate the correlation between BPD and the probability of developing asthma before adulthood. Stata 12.0 was used to conduct the statistical analysis.

RESULTS

The correlation between asthma and BPD in preterm newborns was examined in nine studies. We used a random effect model to pool the OR estimate. Our results indicated a marked increase in the risk of subsequent asthma in preterm infants with BPD [OR = 1.73, 95% confidence interval (CI) = 1.43-2.09]. Moreover, there was no obvious heterogeneity across the studies (P = 0.617, I² = 0%). The pooled OR remained stable and ranged from 1.65 (95% CI = 1.35-2.01) to 1.78 (95% CI = 1.43-2.21). Regarding publication bias, the funnel plot for asthma risk did not reveal any noticeable asymmetry. We further performed Begg's and Egger's tests to quantitatively evaluate publication bias. There was no evidence of a publication bias for asthma risk (P > |Z| = 0.602 for Begg's test, and P > |t| = 0.991 for Egger's test).

CONCLUSIONS

Our findings indicate that preterm infants with BPD have a much higher risk of developing asthma in the future (OR = 1.73, 95% CI = 1.43-2.09). Preterm infants with BPD may benefit from long-term follow-up.

Family history of asthma influences outpatient respiratory outcomes in children with BPD

INTRODUCTION

Preterm children with bronchopulmonary dysplasia (BPD) are at increased risk for intermittent and chronic respiratory symptoms during childhood and adult life. Identifying children at higher risk for respiratory morbidities in the outpatient setting could help improve long-term outcomes. In this study, we hypothesized that a family history of asthma (FHA) is a risk factor for higher acute care usage and respiratory symptoms in preterm infants/children with BPD, following initial discharge home.

METHODS

Subjects were recruited from the Johns Hopkins Bronchopulmonary Dysplasia outpatient clinic between January 2008 and February 2020 (n = 827). Surveys were administered to caregivers and demographics and clinical characteristics were obtained through chart review.

RESULTS

Demographic features associated with FHA included public health insurance, lower median household income, and nonwhite race. Children with FHA had higher odds of emergency department (ED) visits, systemic steroid use, nighttime respiratory symptoms, and activity limitations. There was no association between FHA and BPD severity.

CONCLUSION

This study found that children with BPD and FHA were more likely to have respiratory symptoms and acute care usage during the first 3 years of life and that FHA was associated with lower socioeconomic status. Although there was no association between FHA and BPD severity, FHA could predict an increased likelihood of both ED visits and need for systemic steroids in infants/children with BPD followed in the outpatient setting.

Increased aortic stiffness and elevated blood pressure in response to exercise in adult survivors of prematurity

Objectives

Adults born prematurely have an increased risk of early heart failure. The impact of prematurity on left and right ventricular function has been well documented, but little is known about the impact on the systemic vasculature. The goals of this study were to measure aortic stiffness and the blood pressure response to physiological stressors; in particular, normoxic and hypoxic exercise.

Methods

Preterm participants (n = 10) were recruited from the Newborn Lung Project Cohort and matched with term‐born, age‐matched subjects (n = 12). Aortic pulse wave velocity was derived from the brachial arterial waveform and the heart rate and blood pressure responses to incremental exercise in normoxia (21% O₂) or hypoxia (12% O₂) were evaluated.

Results

Aortic pulse wave velocity was higher in the preterm groups. Additionally, heart rate, systolic blood pressure, and pulse pressure were higher throughout the normoxic exercise bout, consistent with higher conduit artery stiffness. Hypoxic exercise caused a decline in diastolic pressure in this group, but not in term‐born controls.

Conclusions

In this first report of the blood pressure response to exercise in adults born prematurely, we found exercise‐induced hypertension relative to a term‐born control group that is associated with increased large artery stiffness. These experiments performed in hypoxia reveal abnormalities in vascular function in adult survivors of prematurity that may further deteriorate as this population ages.

Effect of sibship asthma on newborns with transient tachypnea of the newborn (TTN)

BACKGROUND

A number of studies have demonstrated that transient tachypnea of the newborn (TTN) is a risk factor for later asthma. The present study attempts to determine whether older sibling asthma is a risk factor for TTN.

METHODS

Medical records of 1318 newborns from neonatal intensive care and delivery units were studied. None of the subjects were first-born, and thus, all had older siblings. Clinical data of mothers and their children were obtained from medical records. Data items included date of birth, gestational age (GA) at birth, birth weight, gender, mode of delivery including Normal Spontaneous Delivery or caesarean section (CS) and whether pre-labour CS or not, reasons for CS, number of pregnancies, number of children, asthma of mothers and siblings, whether the newborn had TTN or not. Logistic regression analysis was used to assess the association between siblings' asthma and TTN.

RESULTS

Pre-labour CS, maternal asthma, GA, babies with large and small birth weight for GA, number of pregnancies and children (three and more) were found to be significantly associated with TTN. Siblings' asthma was found to be independently associated with a diagnosis of TTN.

CONCLUSIONS

Both pre-labour CS and mothers with asthma were common risk factors for the development of TTN. An association was present between TTN and siblings' asthma even in infants whose mothers did not have asthma.

Preschool Asthma Symptoms in Children Born Preterm: The Relevance of Lung Function in Infancy

Background: The aim of the study is to assess whether lung function of infants born preterm predicts wheezing in pre-school age. Methods: A survey of the core wheezing questionnaire of the International Study on Asthma and Allergy in Children was administered to parents of preterm newborns, to whom lung function tests were performed at a corrected age of six months, and who, at the time of the survey, were between three and nine years of age. Results: Low values of all lung function parameters measured, except FVC, were predictors of wheezing at some time in life, (FEV0.5 OR: 0.62 (95%CI 0.39; 0.995); FEV0.5/FVC OR: 0.73 (0.54; 0.99)) FEF75 OR: 0.60 [0.37; 0.93]; FEF25-75 OR: 0.57 (0.37; 0.89)); and of wheezing in the past year (FEV0.5 OR: 0.36 (0.17; 0.76); FEV0.5/FVC OR: 0.59 (0.38; 0.93); FEF75 OR: 0.38 [0.19; 0.76]; FEF25-75 OR: 0.35 (0.17; 0.70). In addition, FEV0.5/FVC values lower than the lowest limit of normality, were predictive of hospital admissions due to wheezing (OR: 3.07; (1.02; 9.25)). Conclusions: Limited lung function in infancy is predictive of both future wheezing and hospitalization for a wheezing episode.

New Risk Factors for Transient Tachypnea of the Newborn and Childhood Asthma: A Study of Clinical Data and a Survey of Parents

Objectives: It is established that transient tachypnea of the newborn (TTN) is associated with an increased risk of early childhood asthma. However, the question remains whether both asthma and TTN have common risk factors as well as the same underlying etiology. This study aims to determine possible risk factors for TTN as well as early childhood asthma.

Methods: This study was carried out in two phases. While the first phase included medical records of 1318 newborns, the second phase consisted of a phone survey.

Results: Elective cesarean section (ECS), maternal asthma, gestational age (GA), babies with large and small birth weight, number of pregnancies, and number of children were found to be significantly associated with TTN. ECS, maternal asthma, length of the hospital stay due to TTN, and O₂ treatment were statistically significant for asthma. TTN was found to be associated with a subsequent diagnosis of childhood asthma after adjusting for ECS and maternal asthma.

Conclusions: Both ECS and maternal asthma are the common risk factors for the development of both TTN and childhood asthma as previously reported. In order to uncover this association, when ECS is taken out, it is seen that the association between TTN and asthma is stronger. Furthermore, O₂ treatment and duration of hospital stay due to TTN were also found to be associated with childhood asthma. Association of maternal allergic rhinitis and eczema with TTN was investigated and there was no relationship between maternal allergic rhinitis or maternal eczema and the subsequent diagnosis of TTN.

Prematurity as an Independent Risk Factor for the Development of Pulmonary Disease

OBJECTIVES

To determine if premature infants without bronchopulmonary dysplasia (BPD) are at similar risk for developing pulmonary morbidity as compared with those with BPD and if there are differences in management of care.

STUDY DESIGN

We retrospectively abstracted information from our electronic medical record from January 1, 2006, to December 31, 2015, for primary care patients born at <30 weeks of gestation (n = 811). Multivariate models determined the impact of BPD on a diagnosis of respiratory disease, respiratory medications, subspecialty visits, and emergency department use or hospitalizations after adjusting for gestational age, sex, insurance type, and race.

RESULTS

Infants with BPD were more likely to be diagnosed with asthma than those without BPD (75% vs 60%; OR, 1.8; 95% CI, 1.27-2.54), but not all respiratory conditions (OR, 1.56; 95% CI, 0.7-3.51), and were more likely to be referred to a pulmonologist (relative risk, 5.98; 95% CI, 4.1-8.74). Infants with BPD were more likely to be hospitalized for respiratory conditions than those without BPD (50% vs 30%; relative risk, 2.44; 95% CI, 1.73-3.45).

CONCLUSIONS

Although infants with BPD were more likely to have a diagnosis of asthma and be readmitted for respiratory conditions, 60% of infants without BPD were also diagnosed with asthma and 30% were readmitted. There were significant differences in the management of patients, including time to pulmonary referral and prescription rates for inhaled corticosteroids. Practitioners should consider all patients born prematurely at high risk for respiratory morbidity.

Chronic Conditions and Health Care Needs of Adolescents Born at 23 to 25 Weeks' Gestation

OBJECTIVE

We examined chronic conditions, functional limitations, and special health care needs in extremely preterm children (EPT; 23-25 weeks' gestation) born between 1992 and 1998 at 2 Swedish tertiary care centers that offered regional and active perinatal care to all live-born EPT infants.

METHODS

Of 134 surviving EPT children, 132 (98%) were assessed at 10 to 15 years of age alongside 103 term-born controls. Identification of children with functional limitations and special health care needs was based on a questionnaire administered to parents. Categorization of medical diagnoses and developmental disabilities was based on child examinations, medical record reviews, and parent questionnaires.

RESULTS

In logistic regression analyses adjusting for social risk factors and sex, the EPT children had significantly more chronic conditions than the term-born controls, including functional limitations (64% vs 6%; odds ratio [OR], 15; 95% confidence interval [CI], 6.1-37.2; P < .001), compensatory dependency needs (60% vs 29%; OR, 3.8; 95% CI, 2.2-6.6; P < .001), and services above those routinely required by children (64% vs 25%; OR, 5.4; 95% CI, 3.0-9.6; P < .001). Specific diagnoses and disabilities for the EPT group versus controls included cerebral palsy (9.1% vs 0%; P < .001), asthma (21.2% vs 6.8%; P = 001), IQ < -2 SD (31.1% vs 4.9%; P < .001), poor motor skills without neurosensory impairment (21.9% vs 1.9%; P < .001), and psychiatric conditions (15.2% vs 1.9%; P < .001).

CONCLUSIONS

Adolescents born EPT have considerable long-term health and educational needs. Few had severe impairments that curtailed major activities of daily life.

Lung Function and Bronchial Hyperresponsiveness in Adults Born Prematurely. A Cohort Study

RATIONALE

Bronchopulmonary dysplasia and the long-term consequences of prematurity are underrecognized entities, unfamiliar to adult clinicians. Well described by the pediatric community, these young adults are joining the ranks of a growing population of adults with chronic lung disease.

OBJECTIVES

To describe the quality of life, pulmonary lung function, bronchial hyperresponsiveness, body composition, and trends in physical activity of adults born prematurely, with or without respiratory complications.

METHODS

Four groups of young adults born in Canada between 1987 and 1993 were enrolled in a cohort study: (1) preterm subjects with no neonatal respiratory complications, (2) preterm subjects with neonatal respiratory distress syndrome, (3) preterm subjects with bronchopulmonary dysplasia, and (4) subjects born at term. The following measurements were compared across the four groups: health-related quality of life, respiratory health, pulmonary function, methacholine challenge test results, and sedentary behavior and physical activity level.

MEASUREMENTS AND MAIN RESULTS

Adult subjects who had bronchopulmonary dysplasia in infancy had mild airflow obstruction (FEV1, 80% predicted; FEV1/FCV ratio, 70) and gas trapping compared with others. They also had less total active energy expenditure and more time spent in sedentary behavior compared with subjects born at term. All preterm groups had a high prevalence of bronchial hyperresponsiveness compared with term subjects.

CONCLUSIONS

In a population-derived, cross-sectional study, we confirmed previous reports that adults 21 or 22 years of age who were born prematurely with neonatal bronchopulmonary dysplasia are more likely to have airflow obstruction, bronchial hyperresponsiveness, and pulmonary gas trapping than subjects born prematurely without bronchopulmonary dysplasia or at term. Clinicians who care for adults need to be better informed of the long-term respiratory consequences of premature birth to assist young patients in maintaining lung function and health.

Understanding the Short- and Long-Term Respiratory Outcomes of Prematurity and Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease associated with premature birth that primarily affects infants born at less than 28 weeks' gestational age. BPD is the most common serious complication experienced by premature infants, with more than 8,000 newly diagnosed infants annually in the United States alone. In light of the increasing numbers of preterm survivors with BPD, improving the current state of knowledge of long-term respiratory morbidity for infants with BPD is a priority. We undertook a comprehensive review of the published literature to analyze and consolidate current knowledge of the effects of BPD that are recognized at specific stages of life, including infancy, childhood, and adulthood. In this review, we discuss both the short-term and long-term respiratory outcomes of individuals diagnosed as infants with the disease and highlight the gaps in knowledge needed to improve early and lifelong management of these patients.

Respiratory outcomes of the surfactant positive pressure and oximetry randomized trial (SUPPORT)

OBJECTIVE

To explore the early childhood pulmonary outcomes of infants who participated in the National Institute of Child Health and Human Development's Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial (SUPPORT), using a factorial design that randomized extremely preterm infants to lower vs higher oxygen saturation targets and delivery room continuous positive airway pressure (CPAP) vs intubation/surfactant.

STUDY DESIGN

The Breathing Outcomes Study, a prospective secondary study to the Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial, assessed respiratory morbidity at 6-month intervals from hospital discharge to 18-22 months corrected age (CA). Two prespecified primary outcomes-wheezing more than twice per week during the worst 2-week period and cough longer than 3 days without a cold-were compared for each randomized intervention.

RESULTS

One or more interviews were completed for 918 of the 922 eligible infants. The incidences of wheezing and cough were 47.9% and 31.0%, respectively, and did not differ between the study arms of either randomized intervention. Infants randomized to lower vs higher oxygen saturation targets had a similar risk of death or respiratory morbidity (except for croup and treatment with oxygen or diuretics at home). Infants randomized to CPAP vs intubation/surfactant had fewer episodes of wheezing without a cold (28.9% vs 36.5%; P<.05), respiratory illnesses diagnosed by a doctor (47.7% vs 55.2%; P<.05), and physician or emergency room visits for breathing problems (68.0% vs 72.9%; P<.05) by 18-22 months CA.

CONCLUSION

Treatment with early CPAP rather than intubation/surfactant is associated with less respiratory morbidity by 18-22 months CA. Longitudinal assessment of pulmonary morbidity is necessary to fully evaluate the potential benefits of respiratory interventions for neonates.

Ventilatory control in infants, children, and adults with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), or chronic lung disease of prematurity, occurs in ~30% of preterm infants (15,000 per year) and is associated with a clinical history of mechanical ventilation and/or high inspired oxygen at birth. Here, we describe changes in ventilatory control that exist in patients with BPD, including alterations in chemoreceptor function, respiratory muscle function, and suprapontine control. Because dysfunction in ventilatory control frequently revealed when O2 supply and CO2 elimination are challenged, we provide this information in the context of four important metabolic stressors: stresses: exercise, sleep, hypoxia, and lung disease, with a primary focus on studies of human infants, children, and adults. As a secondary goal, we also identify three key areas of future research and describe the benefits and challenges of longitudinal human studies using well-defined patient cohorts.

Performance of commonly used respiratory questionnaire items in a cohort of infants born preterm

Background

Items from respiratory questionnaires validated in older children are often used in research studies of preterm infants, although they have not been validated in this population. We aimed to assess both test-retest reliability and convergent validity of a group of commonly used respiratory questionnaire items in a cohort of preterm infants.

Methods

The health status of 300 preterm infants was assessed by telephone questionnaire as part of a prospective cohort study. The questionnaire items analyzed in this study included six commonly used respiratory questions. The questionnaire responses used in this analysis were from the telephone follow-up in this cohort at six months of age adjusted for prematurity. A repeat interview one to two weeks after this interview was performed in a subset of subjects to assess test-retest reliability. The convergent validity of the respiratory items was also assessed by calculating the associations among the responses to the respiratory questions.

Results

A total of 43 infants were singletons that met the criteria for test-retest reliability analysis. All of the respiratory questions demonstrated fair to strong test-retest reliability. Among 206 respondents, respiratory questionnaire items also demonstrated strong convergent validity, in that caretakers reporting wheezing or whistling in the chest were significantly more likely to also report other respiratory events.

Conclusions

This selection of standard respiratory questionnaire items performed well for research purposes in this population.

Correlation of urinary inflammatory and oxidative stress markers in very low birth weight infants with subsequent development of bronchopulmonary dysplasia

Currently, bronchopulmonary dysplasia (BPD) occurs almost exclusively in pre-term infants. In addition to prematurity, other factors like oxygen toxicity and inflammation can contribute to the pathogenesis. This study aimed to compare urinary inflammatory and oxidative stress markers between the no/mild BPD group and moderate/severe BPD group and between BPD cases with significant early lung disease like respiratory distress syndrome (RDS) ('classic' BPD) and with minimal early lung disease ('atypical' BPD). A total of 60 patients who were a gestational age < 30 weeks or a birth weight < 1250 g were included. Urine samples were obtained on the 1(st), 3(rd) and 7(th) day of life and measured the levels of leukotriene E(4) (LTE(4)) and 8-hydroxydeoxyguanosine (8-OHdG). The 8-OHdG values on the 3(rd) day showed significant correlation to duration of mechanical ventilation. The 8-OHdG levels on the 7(th) day were the independent risk factor for developing moderate/severe BPD. In 'classic' BPD, the 8-OHdG values on the 3(rd) day were higher than those of 'atypical' BPD. In 'atypical' BPD, the LTE(4) values on the 7(th) day were higher than the values in 'classic' BPD. These results suggest that oxidative DNA damage could be the crucial mechanism in the pathogenesis of current BPD and the ongoing inflammatory process could be an important mechanism in 'atypical' BPD.

Impact at age 11 years of major neonatal morbidities in children born extremely preterm

BACKGROUND

Uncertainty continues regarding the extent to which neonatal morbidities predict poor long-term outcome and functional abilities in extremely preterm infants.

OBJECTIVE

The goal of this study was to determine the impact of bronchopulmonary dysplasia (BPD), ultrasonographic signs of brain injury, and severe retinopathy of prematurity (ROP) on 11-year outcomes in infants born at <26 weeks' gestation.

METHODS

A total of 247 infants were born alive before 26 completed weeks of gestation from 1990 through 1992 in all of Sweden, and 98 (40%) survived to a postmenstrual age of 36 weeks. Main outcome measures were (1) poor outcome, defined as combined end point of death after 36 weeks' postmenstrual age or survival with at least 1 major disability at 11 years, and (2) consequences of chronic conditions in the survivors according to a validated instrument administered to parents.

RESULTS

Brain injury and severe ROP but not BPD correlated independently with poor outcome at 11 years of age. Among children who were free from BPD, brain injury, and severe ROP, 10% had a poor outcome. Corresponding rates with any 1, any 2, and all 3 neonatal morbidities were 19%, 58%, and 80%, respectively. Multivariate analysis revealed that brain injury and severe ROP were associated with high rates of consequences of chronic conditions.

CONCLUSIONS

In infants born extremely preterm who survive to a postmenstrual age of 36 weeks, severe ROP and brain injury separately predict the risk of death or major disability at 11 years of age. Thus, continued research to determine how to prevent these complications of prematurity is critical.

Gastrin-releasing peptide blockade as a broad-spectrum anti-inflammatory therapy for asthma

Gastrin-releasing peptide (GRP) is synthesized by pulmonary neuroendocrine cells in inflammatory lung diseases, such as bronchopulmonary dysplasia (BPD). Many BPD infants develop asthma, a serious disorder of intermittent airway obstruction. Despite extensive research, early mechanisms of asthma remain controversial. The incidence of asthma is growing, now affecting >300 million people worldwide. To test the hypothesis that GRP mediates asthma, we used two murine models: ozone exposure for air pollution-induced airway hyperreactivity (AHR), and ovalbumin (OVA)-induced allergic airway disease. BALB/c mice were given small molecule GRP blocking agent 77427, or GRP blocking antibody 2A11, before exposure to ozone or OVA challenge. In both models, GRP blockade abrogated AHR and bronchoalveolar lavage (BAL) macrophages and granulocytes, and decreased BAL cytokines implicated in asthma, including those typically derived from Th1 (e.g., IL-2, TNFα), Th2 (e.g., IL-5, IL-13), Th17 (IL-17), macrophages (e.g., MCP-1, IL-1), and neutrophils (KC = IL-8). Dexamethasone generally had smaller effects on all parameters. Macrophages, T cells, and neutrophils express GRP receptor (GRPR). GRP blockade diminished serine phosphorylation of GRPR with ozone or OVA. Thus, GRP mediates AHR and airway inflammation in mice, suggesting that GRP blockade is promising as a broad-spectrum therapeutic approach to treat and/or prevent asthma in humans.

Late preterm birth and risk of developing asthma

OBJECTIVE

To evaluate the association between gestational age at birth (late preterm vs term) and risk for physician-diagnosed asthma.

STUDY DESIGN

We conducted a retrospective cohort study using the Third National Health and Nutrition Examination Survey (1988-1994) linked natality files. The study included children age 2-83 months from singleton births, born late preterm (n=537) or term (n=5650). Using survival analysis, we modeled time to diagnosis of asthma; children with no asthma diagnosis were censored at the age of their survey interview. We used Cox proportional hazard regression to estimate hazard ratios and 95% confidence intervals for gestational age and asthma risk, adjusting for maternal age, maternal education, parental history of asthma/hay fever, maternal smoking history during pregnancy, race/ethnicity, and sex of the child.

RESULTS

Adjusted analysis showed that physician-diagnosed asthma was modestly associated with late preterm birth (hazard ratio, 1.3; 95% confidence interval, 0.8-2.0), but this association was not statistically significant (P=.30).

CONCLUSIONS

Our study found that late preterm birth was not associated with a diagnosis of asthma in early childhood.

Antenatal steroid treatment reduces childhood asthma risk in very low birth weight infants without bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) and very low birth weight (VLBW) are associated with increased incidences of asthma and pulmonary dysfunction in childhood. However, no studies exist which examine asthma risk factors in children who were VLBW infants and did not have BPD. To address this issue, we assessed the asthma incidence and risk factors for asthma in 117 children (approximate mean age of 5 years) who were VLBW [<1500 g, mean gestational age (GA): 30 weeks] infants without BPD. The risk factors were both perinatal (such as steroid treatment, mechanical ventilation, surfactant treatment) and environmental (parental smoking, pet adoption, etc). The asthma incidence was 18.8%. Following multivariate analysis, it was determined that a family history of atopy was a strong risk factor for childhood asthma. Maternal antenatal steroid treatment was associated with a significantly reduced risk for asthma. GA and birth weight were not predictive of childhood asthma. These findings indicate that a history of familial atopy and antenatal steroid treatment are positively and negatively associated (independent of BPD) with childhood asthma in VLBW infants. The finding regarding antenatal steroid treatment warrants more extensive investigations.

The association between family history of asthma and the prevalence of asthma among US adults: National Health and Nutrition Examination Survey, 1999-2004

PURPOSE

To assess the overall prevalence of asthma and the association between family history of asthma and the prevalence of asthma among US adults.

METHODS

We analyzed National Health and Nutrition Examination Survey data from 1999 to 2004 for 15,008 respondents aged 20 years or older with no history of emphysema. We divided respondents into three familial risk groups (high, moderate, and average) on the basis of the number and closeness of relatives, that they reported as having asthma and then assessed the asthma prevalence in each. We also assessed associations between asthma prevalence and age, sex, race/ethnicity, income, body mass index, smoking status, household smoking exposure, and physical activity.

RESULTS

By our definitions, 2.3% of respondents were at high, 13.0% at moderate, and 84.7% at average familial risk for asthma. The crude prevalence of self-reported lifetime asthma was 11.5% (95% confidence interval [CI]: 10.7-12.3%) among all respondents, and 37.6% (95% CI: 30.4-45.4%), 20.4% (95% CI: 18.2-22.7%), and 9.4% (95% CI: 8.7-10.2%) among those at high, moderate, and average familial risk, respectively. Among all risk factors we looked at, family history had the strongest association with lifetime asthma prevalence, and the association remained significant after adjustments for other risk factors. Compared with average familial risk, the adjusted odds ratios for lifetime asthma were 2.4 (95% CI: 2.0 -2.8) for moderate and 4.8 (95% CI: 3.5-6.7) for high familial risk.

CONCLUSION

Our findings showed that a family history of asthma is an important risk factor for asthma and that familial risk assessments can help identify people at highest risk for developing asthma. Additional research is needed to assess how health care professionals can use family history information in the early detection and management of asthma.

Gastrin-releasing peptide, immune responses, and lung disease

Gastrin-releasing peptide (GRP) is produced by pulmonary neuroendocrine cells (PNECs), with highest numbers of GRP-positive cells present in fetal lung. Normally GRP-positive PNECs are relatively infrequent after birth, but PNEC hyperplasia is frequently associated with chronic lung diseases. To address the hypothesis that GRP mediates chronic lung injury, we present the cumulative evidence implicating GRP in bronchopulmonary dysplasia (BPD), the chronic lung disease of premature infants who survive acute respiratory distress syndrome. The availability of well-characterized animal models of BPD was a critical tool for demonstrating that GRP plays a direct role in the early pathogenesis of this disease. Potential mechanisms by which GRP contributes to injury are analyzed, with the main focus on innate immunity. Autoreactive T cells may contribute to lung injury late in the course of disease. A working model is proposed with GRP triggering multiple cell types in both the innate and adaptive immune systems, promoting cascades culminating in chronic lung disease. These observations represent a paradigm shift in the understanding of the early pathogenesis of BPD, and suggest that GRP blockade could be a novel treatment to prevent this lung disease in premature infants.

One-year respiratory outcomes of preterm infants enrolled in the Nitric Oxide (to prevent) Chronic Lung Disease trial

OBJECTIVE

To identify whether inhaled nitric oxide treatment decreased indicators of long-term pulmonary morbidities after discharge from the neonatal intensive care unit.

STUDY DESIGN

The Nitric Oxide (to Prevent) Chronic Lung Disease trial enrolled preterm infants (<1250 g) between 7 to 21 days of age who were ventilated and at high risk for bronchopulmonary dysplasia. Follow-up occurred at 12 +/- 3 months of age adjusted for prematurity; long-term pulmonary morbidity and other outcomes were reported by parents during structured blinded interviews.

RESULTS

A total of 456 infants (85%) were seen at 1 year. Compared with control infants, infants randomized to inhaled nitric oxide received significantly less bronchodilators (odds ratio [OR] 0.53 [95% confidence interval 0.36-0.78]), inhaled steroids (OR 0.50 [0.32-0.77]), systemic steroids (OR 0.56 [0.32-0.97]), diuretics (OR 0.54 [0.34-0.85]), and supplemental oxygen (OR 0.65 [0.44-0.95]) after discharge from the neonatal intensive care unit. There were no significant differences between parental report of rehospitalizations (OR 0.83 [0.57-1.21]) or wheezing or whistling in the chest (OR 0.70 [0.48-1.03]).

CONCLUSIONS

Infants treated with inhaled nitric oxide received fewer outpatient respiratory medications than the control group. However, any decision to institute routine use of this dosing regimen should also take into account the results of the 24-month neurodevelopmental assessment.

Antenatal steroid therapy and childhood asthma: Is there a possible link?

This paper presents a hypothesis that fetal exposure to corticosteroids is an independent risk factor for the development of asthma in childhood. The prevalence of childhood asthma saw a dramatic rise from the 1980s up until the early 2000s. Among the explanations for the increase in asthma prevalence included interest in exposures arising in the gestational period. Overlapping the time period of the increasing prevalence of childhood asthma is the increased use of antenatal corticosteroid therapy for fetal lung maturation. Through an examination of the published literature, a time dependent association between year of birth (and hence exposure to the antenatal corticosteroids) and the relationship between preterm birth and childhood asthma is noted. A brief review of the trends in the prevalence of asthma, the use of antenatal corticosteroids including their established latent effects and the time dependant association between preterm birth and the risk of childhood asthma are provided.

Pulmonary testing using peak flow meters of very low birth weight children born in the perisurfactant era and school controls at age 10 years

We determined lung function at age 10 years in very low birthweight (VLBW, <or=1,500 g) children and controls, and compared the sensitivity to detect subgroup differences by peak expiratory flow (PEF), forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and their diurnal variation. VLBW children were recruited across the perisurfactant era at admission to six NICUs in Wisconsin and Iowa, and controls from area classrooms. Two hundred sixty five VLBW children and 360 controls were tested by the Jaeger AM1 peak flow meter at age 10 years. Two hundred six VLBW and 79 controls had additional home monitoring. Abnormality was defined as observed/predicted ratio <0.8 for PEF, FEV(1), and FVC, and by criteria of Pelkonen for diurnal PEF variation. VLBW children were compared to controls, VLBW children with bronchopulmonary dysplasia (BPD) to those without, and those with respiratory conditions to those without. PEF and FEV(1) showed high reproducibility (intraclass correlations, ICC 0.75-0.83). Controls and VLBW children with and without BPD differed significantly on all measures. Baseline test results did not differ across birth years, but PEF variation was less after surfactant availability (P = 0.04). Observed over predicted FEV(1) was the most sensitive in detecting differences between groups (P < 0.001), with mean (s.d.) 0.97 (0.12) for controls, 0.88 (0.14) for VLBW children without BPD, and 0.78 (0.13) for those with BPD. Odds ratios for abnormality were especially high with respiratory medication use during the first 5 years of life, 4.4 (95% CI: 2.0-9.8) for FEV(1) and 5.1 (95% CI: 2.0-13.2) for diurnal PEF variation. Our results show that respiratory abnormalities persist to at least age 10 years for VLBW children born in the surfactant era.

Chronic conditions, functional limitations, and special health care needs in 10- to 12-year-old children born at 23 to 25 weeks' gestation in the 1990s: a Swedish national prospective follow-up study

BACKGROUND

Children born extremely immature (gestational age < 26 weeks' gestation) increasingly reach school age. Information on their overall functioning and special health care needs is necessary to plan for their medical and educational services. This study was undertaken to examine neurosensory, medical, and developmental conditions together with functional limitations and special health care needs of extremely immature children compared with control subjects born at term.

METHODS

We studied 11-year-old children born before 26 completed weeks of gestation in all of Sweden from 1990 through 1992. All had been evaluated at 36 months' corrected age. Identification of children with chronic conditions lasting > or = 12 months was based on a questionnaire administered to parents. Neurosensory impairments were identified by reviewing health records. Information regarding other specific medical diagnoses and developmental disabilities was obtained by standard parent and teacher questionnaires.

RESULTS

Of 89 eligible children, 86 (97%) were studied at a mean age of 11 years. An equal number of children born at term served as controls. Logistic-regression analyses adjusting for social risk factors and gender showed that significantly more extremely immature children than controls had chronic conditions, including functional limitations (64% vs 11%, respectively), compensatory dependency needs (59% vs 25%), and services above those routinely required by children (67% vs 22%). Specific diagnoses or disabilities with higher rates in extremely immature children than in controls included neurosensory impairment (15% vs 2%), asthma (20% vs 6%), poor motor skills of > 2 SDs above the mean (26% vs 3%), poor visual perception of > 2 SDs above the mean (21% vs 4%), poor learning skills of > 2 SDs above the mean (27% vs 3%), poor adaptive functioning with T scores of < 40 (42% vs 9%), and poor academic performance with T score < 40 (49% vs 7%).

CONCLUSIONS

Children born extremely immature have significantly greater health problems and special health care needs at 11 years of age. However, few children have severe impairments that curtail major activities of daily living.

Defects in surfactant synthesis: clinical implications

Since the original description of deficiency of the pulmonary surfactant in premature newborn infants by Avery and Mead in 1959, respiratory distress syndrome has most commonly been attributed to developmental immaturity of surfactant production. Studies of different ethnic groups, gender, targeted gene ablation in murine lineages, and recent clinical reports of monogenic causes of neonatal respiratory distress syndrome have demonstrated that genetic defects disrupt pulmonary surfactant metabolism and cause respiratory distress syndrome, especially in term or near-term infants and in older infants, children, and adults. In contrast to developmental causes of respiratory distress, which may improve as infants and children mature, genetic causes result in both acute and chronic (and potentially irreversible) respiratory failure.

G protein-coupled receptor for asthma susceptibility associates with respiratory distress syndrome

BACKGROUND

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) have some common features with asthma.

AIM

To study whether G protein-coupled receptor for asthma susceptibility (GPRA) contributes to RDS or BPD.

METHODS

A haplotype association study was performed in a case-control setting of 521 Finnish infants (including 176 preterm neonates with RDS and 37 with BPD). Immunoreactivity of GPRA isoforms A and B was determined in pulmonary samples of fetuses, term infants and preterm infants with RDS or BPD. GPRA mRNA expression was determined by quantitative real-time polymerase chain reaction (PCR) in samples from nasal respiratory epithelium of adults, term infants and preterm infants.

RESULTS

In infants with RDS born at 32-35 weeks of gestation, GPRA haplotype H1 was significantly underrepresented in RDS, whereas haplotype H4/H5 was associated with an increased risk. As in asthma, GPRA B isoform was induced in bronchial smooth muscle cells in RDS and BPD. In nasal respiratory epithelium, relative GPRA mRNA expression was strong in adults, weak in preterm and slightly higher in term samples.

CONCLUSIONS

The results suggest that near-term RDS and asthma share the same susceptibility and protective GPRA haplotypes. Altered GPRA expression may play a role in the pathogenesis of RDS and BPD in preterm infants.

Nonassociation of Interleukin 4 Intron 3 and 590 Promoter Polymorphisms with Bronchopulmonary Dysplasia for Ventilated Preterm Infants

Interleukin 4 (IL-4) stimulates and amplifies the inflammatory response, stimulates collagen synthesis in fibroblasts, promotes the progression to fibrosis and has been shown to inhibit the production of several inflammatory cytokines in the development of bronchopulmonary dysplasia (BPD) and airway hyperreactivity. We aimed to investigate whether IL-4 polymorphisms in ventilated preterm infants were associated with BPD. BPD was defined as infants who remained dependent on active respiratory support or oxygen supplementation at 36 weeks postconceptional age. A case-control study of 224 preterm infants (<30 weeks) who had respiratory distress syndrome and needed intermittent mandatory ventilation (IMV) were undertaken between January 1999 and December 2003. The typing of each genetic polymorphism was performed by polymerase-chain-reaction-based restriction analysis. Genotype distribution and allelic frequencies were compared between ventilated preterm infants who developed BPD and those who did not and the duration of IMV. The demography of these ventilated BPD and non-BPD preterm infants was not different. We observed no significant differences in genotype distribution or allelic frequency of the IL-4 intron 3 or IL-4 promoter polymorphisms between ventilated preterm infants who developed BPD and who did not. There was no significant association of the genotype or allelic frequency of IL-4 polymorphism with duration of IMV. We conclude that neither IL-4 intron 3 nor the 590 promoter polymorphism is a useful marker for predicting the susceptibility to BPD in ventilated Taiwanese preterm infants.

Childhood asthma hospitalization risk after cesarean delivery in former term and premature infants

BACKGROUND

Cesarean delivery modifies infant gut bacterial flora composition, which may result in hindered tolerance to allergenic substances, thereby increasing the risk of asthma in accordance with the hygiene hypothesis. Results of previous studies regarding an association between birth route and asthma are conflicting, and these studies have not evaluated some potential confounding effects, including prematurity and maternal asthma.

OBJECTIVE

To determine whether cesarean delivery in full-term and premature infants increases the risk of subsequent childhood asthma hospitalization.

METHODS

We conducted a case-control study using the Washington State Birth Events Record Database linked to statewide hospitalization data. The study included 2,028 children hospitalized for asthma (cases) and 8,292 age-matched controls.

RESULTS

Cesarean delivery was modestly associated with an increased risk of asthma hospitalization (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.04-1.39). However, when analyzed separately, there was an association between cesarean delivery and asthma hospitalization in premature infants (OR, 1.90; 95% CI, 1.09-3.02) but not in full-term infants (OR, 1.15; 95% CI, 0.97-1.34).

CONCLUSIONS

Cesarean delivery was associated with subsequent asthma hospitalization only in premature infants. Because mothers with asthma are reported to have increased rates of cesarean delivery and premature delivery, other factors in addition to the hygiene hypothesis, including genetic and in utero influences associated with maternal asthma, may contribute to the increased risk of asthma in premature infants.

Neonatal respiratory morbidity at term and the risk of childhood asthma

OBJECTIVE

To determine whether neonatal respiratory morbidity at term is associated with an increased risk of later asthma and whether this may explain previously described associations between caesarean delivery and asthma.

DESIGN

Retrospective cohort study using Scottish Morbidity Record (SMR) data of maternity (SMR02), neonatal (SMR11), and acute hospital (SMR01) discharges.

SETTING

Scotland.

PARTICIPANTS

All singleton births at term between 1992-1995 in 23 Scottish maternity hospitals.

MAIN OUTCOME MEASURES

Hospital admission with a diagnosis of asthma in the principal position between 1992 and 2000.

RESULTS

Children who had a diagnosis of transient tachypnoea of the newborn or respiratory distress syndrome were at increased risk of being admitted to hospital with a diagnosis of asthma (hazard ratio (HR) 1.7, 95% confidence interval (95% CI) 1.4 to 2.2, p<0.001). This association was observed both among children delivered vaginally (HR 1.5, 95% CI 1.1 to 2.0, p = 0.007) and among those delivered by caesarean section (HR 2.2, 95% CI 1.6 to 3.0, p<0.001). In the absence of neonatal respiratory morbidity, delivery by caesarean section was weakly associated with the risk of asthma in childhood (HR 1.1, 95% CI 1.0 to 1.2, p = 0.004). The strengths of the associations were similar whether the caesarean delivery was planned or emergency and were not significantly altered by adjustment for maternal, obstetric, and other neonatal characteristics.

CONCLUSIONS

Neonatal respiratory morbidity at term is associated with an increased risk of asthma in childhood which may explain previously described associations between caesarean delivery and later asthma.

Intrauterine smoke exposure: a new risk factor for bronchopulmonary dysplasia?

OBJECTIVE

To evaluate the role of intrauterine smoke exposure and other variables on the development of bronchopulmonary dysplasia (BPD) in infants with birth weight < 1500 g (VLBW).

METHODS

This case-control study investigated 277 VLBW infants (141 cases, 136 controls) admitted at birth to neonatal intensive care unit and survived to discharge. A retrospective telephone interview provided detailed parental information supplementing clinical data. Logistic regression assessed the effects of birth weight < 1000 g, gestational age < 30 weeks (GA<30), respiratory distress syndrome (RDS), neonatal mechanical ventilation > 7 days (MV>7), patent ductus arteriosus (PDA), intrauterine smoke exposure > or = 3 months (ISE), and of parental history of asthma on BPD (oxygen dependency at 28 days with characteristic radiographic abnormalities) occurrence.

RESULTS

Including all variables, only GA<30, RDS and MV>7 were significantly associated with BPD. ISE did not contribute significantly to this model (odds ratio [OR] 1.94; 95% confidence interval 0.88-4.26). Excluding iatrogenic variable MV>7, GA<30, RDS, PDA and ISE (OR 2.21; 95% confidence interval 1.03-4.76) were significantly associated with BPD. Analyzing GA as a continuous variable, the OR was 0.63 for each additional week.

CONCLUSIONS

Prolonged mechanical ventilation, RDS and low gestational age were the major BPD determinants. Intrauterine smoke exposure seems to influence independently BPD development.

Placenta growth factor elevation in the cord blood of premature neonates predicts poor pulmonary outcome

OBJECTIVE

To determine whether an elevated placenta growth factor (PlGF) level in cord blood is associated with increased risk for preterm infants to develop bronchopulmonary dysplasia (BPD).

METHODS

Sixty-three preterm infants who were born at 34 weeks' gestation or earlier were enrolled. Two infants who died before 28 days' postnatal age could not be assigned a BPD status and were excluded. PlGF levels in cord blood were measured using enzyme-linked immunosorbent assay. Mann-Whitney rank sum test, Spearman correlation coefficients, and multivariable linear or logistic regression analyses were used for statistical analysis.

RESULTS

The BPD group had a higher PlGF level, lower gestational age, lower birth weight (BW), higher incidence of endotracheal tube intubation, and longer duration of intubation. The PlGF levels in cord blood correlated negatively with gestational age and BW. However, multivariable logistic regression analyses revealed that only elevated cord blood PlGF levels and BW were associated with BPD after adjusting for all contributing factors. Furthermore, an increased PlGF level in cord blood was significantly correlated with the clinical severity of BPD, as measured by duration of intubation. At 17 mg/dL, the specificity of cord blood PlGF level in predicting BPD was 95%, the sensitivity was 53%, the positive predictive value was 83%, and the negative predictive value was 82%.

CONCLUSIONS

Measuring cord blood PlGF level at birth might be a biological marker for predicting the occurrence of BPD and allowing early therapeutic intervention.

Helper T-lymphocyte-related chemokines in healthy newborns

Atopic disease is characterized by an imbalance in cytokines secreted from Th1 and Th2 lymphocytes. The association between atopy and serum levels of atopy-related chemokines in umbilical cord blood (UCB) has not been evaluated. This study formulates the reference ranges of thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), eotaxin (EOX), monocyte chemotactic protein 1 (MCP-1), and interferon-gamma-inducible protein 10 (IP-10) in UCB of term neonates and investigates the relation between these chemokines and the development of atopy during infancy. The concentrations of total IgE and chemokines in UCB serum were measured by microparticle immunoassay and sandwich enzyme immunoassay, respectively. A total of 124 singleton healthy newborns were investigated. Fifty-three (43%) infants had family history of allergic diseases, and 26 (21%) had increased serum total IgE concentrations. The median (interquartile range) serum TARC, MDC, EOX, MCP-1, and IP-10 concentrations, in pg/mL, were 425 (300-639), 786 (561-1050), 36 (28-45), 156 (116-205), and 38 (29-49), respectively. Multiparity was associated with increased serum MDC (p = 0.017). Serum chemokine concentrations were not associated with total IgE levels or family history of allergies. The median (interquartile range) serum MDC concentrations in newborns who developed wheezing during infancy and those without wheezing were 1259 pg/mL (945-1523) and 782 pg/mL (551-992), respectively (p = 0.010). This study provides reference ranges of Th-specific chemokines in UCB serum of singleton term neonates. Increased serum MDC concentrations at birth are associated with the occurrence of wheezing during infancy.

Association of glutathione-S-transferase-P1 (GST-P1) polymorphisms with bronchopulmonary dysplasia

OBJECTIVE

Reactive oxygen species (ROS) contribute to oxidative lung injury. The glutathione-S-transferases (GST) family and microsomal epoxide hydrolase (mEPHx) enzymes detoxify ROS, and genetic polymorphisms alter this detoxification. We hypothesized that polymorphisms encoding for less efficient enzymes were associated with bronchopulmonary dysphasia (BPD).

STUDY DESIGN

We determined allelic distribution of these polymorphisms in a pilot study of 35 BPD cases and 98 controls. chi2 and regression analysis were performed.

RESULTS

GST P1 val105ile distribution differed between the groups, with the more efficient val/val allele predominantly in controls (p< or =0.05). When controlling for race and sex, BPD cases were less likely to be homozygotes for the val/val isoform (OR 0.21, CI: 0.045-0.95, p=0.04) and more likely to possess the less efficient ile isoform (OR 4.5, CI: 1.0-20.7, p=0.05).

CONCLUSIONS

This pilot study suggests that BPD is associated with the presence of the GST-P1 105ile allele. Future prospective studies are warranted.

Bombesin-like peptides and mast cell responses: relevance to bronchopulmonary dysplasia?

Bombesin-like peptides (BLPs) are elevated in newborns who later develop bronchopulmonary dysplasia (BPD). In baboon models, anti-BLP blocking antibodies abrogate BPD. We now demonstrate hyperplasia of both neuroendocrine cells and mast cells in lungs of baboons with BPD, compared with non-BPD controls or BLP antibody-treated BPD baboons. To determine whether BLPs are proinflammatory, bombesin was administered intratracheally to mice. Forty-eight hours later, we observed increased numbers of lung mast cells. We analyzed murine mast cells for BLP receptor gene expression, and identified mRNAs encoding bombesin receptor subtype 3 and neuromedin-B receptor (NMB-R), but not gastrin-releasing peptide receptor. Only NMB-R-null mice accumulated fewer lung mast cells after bombesin treatment. Bombesin, gastrin-releasing peptide, NMB, and a bombesin receptor subtype 3-specific ligand induced mast cell proliferation and chemotaxis in vitro. These observations support a role for multiple BLPs in promoting mast cell responses, suggesting a mechanistic link between BLPs and chronic inflammatory lung diseases.

High prevalence of asthma in preschool children in Southern Brazil: a population-based study

The prevalence of asthma is increasing in many countries. To measure asthma's prevalence, a sample of 981 children aged 4 years old belonging to a birth cohort from 1993 was studied in Pelotas, a city in southern Brazil. A standardized questionnaire on asthma was given to the children's mothers. Information was also collected on socioeconomic level, housing conditions, genetic factors, nutritional factors, and previous infectious diseases. Current asthma (asthma diagnosed by a doctor during previous 12 months) and current wheeze (presence of wheezing during previous 12 months) were the main outcomes. The prevalence of current asthma was 18.4%, and current wheeze was 21.1%. The data were analyzed by multiple Poisson regression, and the risk factors that remained significant for both "current asthma and current wheeze" were, respectively, nonwhite color (RR = 1.41 and RR = 1.36), low maternal schooling (RR = 1.75 and RR = 1.68 for 0-4 years), history of asthma or allergy in the family (RR = 1.66 and RR = 1.85), and history of rhinitis and eczema in the child (RR = 2.11 and RR = 1.72). Male sex (RR = 1.36) and bronchiolitis (RR = 1.46) were major risk factors only for "current asthma," while smoking in pregnancy (RR = 1.30) and low birth weight (RR = 1.45) were risk factors only for "current wheeze." These results highlight the importance of asthma as a public health problem due to its high prevalence, and support the need of intervention programs against preventable risk factors.

Recurrent wheezing in infants and young children and bronchial hyperresponsiveness: a perspective

Epidemiological studies report a 50% incidence of at least one wheezing episode in young children. If we can argue that 10% of children have asthma sometime during their pediatric years, it still leaves a significant percentage of children with an unexplained cause for their wheezing. Other recognized phenotypes of recurrent wheezing include young children exposed to excessive environmental tobacco smoke (ETS), while other infants wheeze recurrently following a significant episode of bronchiolitis. Bronchial hyperresponsiveness (BHR) is a universally recognized phenomenon of asthma, but its presence in young children with recurrent wheezing is not as well studied. Currently available studies demonstrates that BHR is also seen in young pediatric asthmatics, paralleling what is well recognized in adolescent or adult asthma. In those children with post-bronchiolitis wheezing, BHR appears to be present to a degree; while infants and young children exposed to ETS have increased BHR, as a group. If exaggerated BHR in recurrent wheezing children without asthma has the same inherent disadvantage as it does in asthmatic children, additional studies looking directly at this issue in a longitudinal fashion need to be designed. A hypothesis of BHR in non-asthmatic children is presented that could be studied prospectively.

Populations at risk for developing respiratory syncytial virus and risk factors for respiratory syncytial virus severity: infants with predisposing conditions

According to National Vital Statistics Reports, premature infants (< 36 weeks gestation) account for approximately 7.4% of all births. During the 8 years from 1989 to 1997, multiple births steadily increased across all categories from twin to quintuplet and higher orders. During that same period low birth weight (< 2500 g) births increased almost 12%, and very low birth weight (< 1500 g) births increased approximately 20%.Attendant to these national trends in multiple and preterm births, overall gestation-specific survival rates have improved substantially. This improved outcome can be attributed in large measure to advances in neonatal care and technology. Despite the encouraging statistics on survival, infants born prematurely, at low or very low birth weights and/or with chronic conditions that predispose to lower respiratory tract illness, continue to incur serious risk of long term morbidity and the consumption of inpatient hospital services. In a recent 2-year study of US children, low and very low birth weights were found to be independent risk factors for bronchiolitis-associated mortality. In the past 14 years what defines bronchopulmonary dysplasia (BPD)/chronic lung disease (CLD) has shifted away from clinical, radiographic and pathologic findings in the preterm infant toward the pathophysiology of arrested lung development and the need for supportive care beyond 36 weeks corrected gestational age. The incidence of BPD/CLD ranges from 14 to 43%, with higher rates observed among infants of lower gestational age and birth weight. The health care team approach to the management of BPD directs its efforts toward minimizing pulmonary vascular resistance, alleviating airway obstruction and improving short term lung mechanics. Measures to prevent BPD/CLD attempt to forestall both acute and chronic lung function abnormalities. To that end researchers have investigated the early use of continuous positive airway pressure, vitamin supplementation and recombinant human copper/zinc superoxide dismutase. Despite significant gains in the survival of infants born at lower gestational ages, prematurity, low birth weight and/or underlying chronic pulmonary disease put the pediatric patient at risk for increased frequency and severity of respiratory syncytial virus lower respiratory tract illness and the potential for its long term sequelae.

Urine bombesin-like peptide elevation precedes clinical evidence of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of very low birth weight infants, associated with oxygen therapy, barotrauma, and/or infections. Improved medical care has led to a paradoxically increased incidence of BPD due to greater infant survival. Early prediction of BPD has proven challenging. Increased pulmonary neuroendocrine cells containing bombesin-like peptide immunoreactivity occur in infants with BPD. We hypothesized that elevated urine bombesin-like peptide levels precede BPD. One hundred thirty-two infants, 28-weeks gestation or less, were studied. Urine bombesin-like peptide levels, determined by radioimmunoassay, were normalized for creatinine. BPD was defined as oxygen dependence at 36 weeks postmenstrual age. A first urine bombesin-like peptide level greater than 20,000 pg/mg creatinine (12,500 fmol/mg) between postnatal days 1-4 occurred among 54% of the infants who later developed BPD (p < or = 0.001), versus 10% among non-BPD infants (specificity 90%). Multivariable logistic regression analyses revealed that elevated urine bombesin-like peptide levels are associated with BPD (odds ratio 9.9, 95% confidence interval: 3.4, 29) (p < or = 0.001) after adjusting for all confounding factors. Thus, elevated bombesin-like peptide levels in these infants at 1-4 days after birth are associated with a 10-fold increased risk of developing BPD. Utilizing urine bombesin-like peptide for screening might permit early therapeutic interventions to reduce disease progression and could provide a target for new preventive therapies.

Urinary leukotriene E(4) excretion during the first month of life and subsequent bronchopulmonary dysplasia in premature infants

BACKGROUND

Inflammation plays an important role in the pathogenesis of bronchopulmonary dysplasia (BPD), but the exact nature of this inflammatory process is incompletely understood. Older infants with established BPD have higher levels of urinary leukotriene E(4) (LTE(4)) compared to healthy infants of the same age. This suggests that cysteinyl leukotrienes may play a role in the abnormalities seen in BPD.

OBJECTIVES

To measure urinary LTE(4) levels during the first month of life in premature infants, and to determine whether there are significant differences in premature infants who develop BPD, as compared to those who do not develop BPD.

DESIGN

Prospective, blinded, controlled study.

SETTING

Neonatal ICUs of a tertiary-care university hospital.

METHODS

Thirty-seven premature infants (< 33 weeks of gestational age) were enrolled prospectively at birth. Urinary LTE(4) levels were measured blinded, using a standard radioimmunoassay technique at 2 days, 7 days, and 28 days of life. At 1 month of age, infants were classified as with or without BPD, based on need for supplemental oxygen, and characteristic chest radiographs. Clinical features and urinary LTE(4) were compared between the two groups.

RESULTS

Mean +/- SD gestational age was 29 +/- 2.6 weeks. None of the infants had a family history of asthma. Thirteen of 37 infants were classified as having BPD at 28 days after birth. Mean gestational age in infants who developed BPD was 27 +/- 2.4 weeks, compared to 30 +/- 2 weeks in infants who did not develop BPD (p < 0.05). In infants with BPD, mean urinary LTE(4) levels of urinary creatinine were 1,762 +/- 2,003 pg/mg, 1,236 +/- 992 pg/mg, and 5,541 +/- 5,146 pg/mg at days 2, 7, and 28, respectively, compared to 1,304 +/- 1,195 pg/mg, 1,158 +/- 1,133 pg/mg, and 2,800 +/- 2,080 pg/mg in infants without BPD. LTE(4) levels at 2 days, 7 days, and 28 days did not correlate with the subsequent development of BPD. LTE(4) levels at day 28 were significantly higher than LTE(4) levels at day 2 and day 7 in both groups, even after correcting for gestational age or birth weight (p < 0.05). There was significant inverse correlation between LTE(4) levels at day 2 with gestational age and birth weight (p < 0.05). All 13 infants with BPD received steroid pulses, compared to 3 of 26 infants without BPD. Gestational age and use of postnatal steroid pulses, diuretics, and theophylline (for apnea of prematurity) were significantly associated with each other and with the subsequent development of BPD.

CONCLUSION

Urinary LTE(4) levels measured on the second day of life in very-low-birth-weight infants inversely correlate with gestational age and birth weight. Urinary LTE(4) levels may reflect lung injury and/or inflammation in premature infants, not necessarily related to BPD as it is presently defined.

Early use of inhaled corticosteroids in infancy

The inability to accurately predict the outcome of infants with recurrent wheezy bronchitis makes the early use of inhaled corticosteroids (ICS) controversial. Data from bronchoalveolar lavages and epidemiological surveys suggest a persistent inflammation of the airways in the more severe cases. Prospective studies, mostly with nebulized corticosteroids, have demonstrated clinical efficacy on daytime and nightime symptoms, reduced requirements for rescue bronchodilators and a real steroid sparing effect. In infants with episodic viral-associated wheeze with or without interval symptoms, ICS use carries the risk of overtreatment and of adverse effects. Long-term prospective studies are urgently required to assess the efficacy and safety of ICS and their possible effects on the natural history of infantile asthma.

Pulmonary sequelae in long-term survivors of bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common problem in premature babies. Long-term sequelae are the main concerns.

METHODS

A retrospective review of all BPD children born in Queen Mary Hospital, a teaching hospital of the University of Hong Kong, from January 1987 to December 1995 was conducted. Children with cerebral palsy, immunodeficiency, congenital heart disorders, renal or liver failure were excluded from analysis. Chest radiography (CXR), electrocardiogram (ECG) and pulse oximetry were routinely performed.

RESULTS

Fifty-five children completed the study. The female to male ratio was 1:1.1. The mean gestational age was 28 weeks. Twenty-five children were born with a birthweight of less than 1001 g. Mean age at assessment was 5.4 years. Twenty-four children (44%) demonstrated signs or symptoms of current asthma. Only seven children managed to perform the spirometry satisfactorily. One child had low forced vital capacity and one had hyperresponsive airway. The only risk factor found to be associated with current asthma was the birth month, with those children born early in the year at higher risk of developing current asthma. Seventeen of 48 children (35%) had a bodyweight below the third percentile at the corrected age of 1 year. Eleven of these seventeen children (65%) demonstrated catch-up growth at assessment. Abnormal CXR was found in 25 of 40 children (63%). All had normal pulse oximetry and ECG.

CONCLUSIONS

Bronchopulmonary dysplasia children had a significantly higher risk than the general population of developing current asthma (odds ratio 4.7; 95% confidence interval 3.4-6.5; P<0.0001). The importance of birth month suggests that early life experience is important in the pathogenesis of asthma, even in BPD children. The long-term growth of BPD children was much better than previously reported.

Pediatric origins of adult lung disease. 1. The contribution of airway development to paediatric and adult lung disease

In summary, factors that affect airway growth early in development appear to cause physiological effects that can be persistent. Reduced airway function early in life does not necessarily result in persistent symptoms, but the long term effects and impact on the development of chronic airflow limitation in adults are yet to be determined. Generally, long term sequelae seem to be related to the severity of the initial insult, but the development of persistent increased bronchial responsiveness is an independent risk factor for symptoms and abnormal lung function in later life. In addition, there appear to be separate genetic factors that influence atopy, airway development, and bronchial responsiveness.

Racial differences in physiologic parameters related to asthma among middle-class children

BACKGROUND

Asthma morbidity and mortality are higher in the United States for African-American (AA) children when compared to European-American (EA) children.

STUDY OBJECTIVES

To explore racial differences in physiologic factors associated with pediatric asthma severity.

DESIGN

Cross-sectional.

METHODS

We analyzed data from two groups of children in suburban Detroit, one of which contains non-urban, middle-class AA children, a group not usually included in childhood asthma studies. All children were 6 to 8 years of age. Clinical evaluations included medical history, physical examination, skin testing, spirometry, and methacholine challenge.

RESULTS

The study population (n = 569) was 14% African American, 51% of the participants were male, and the mean age was 6.8 +/- 0.4 years. Socioeconomic status (parental education) was similar overall by race, although some strata-specific differences were observed. The prevalence of physician-diagnosed asthma was 10% for both AA and EA groups. AA children were more reactive to methacholine than EA children (42% vs 22%, respectively; p = 0.001), and had significantly higher total IgE than EA children (geometric mean, 60. 6 vs 27.5 IU/mL; p = 0.001). Serum IgE was related to methacholine reactivity in EA children (p = 0.001), but not AA children (p = 0. 73). These differences remained after adjustment for gender, age, parental education, parental smoking, and maternal smoking during pregnancy.

CONCLUSIONS

Our data support previous reports of racial differences in lung volume, airway responsiveness, and serum IgE concentrations. We found a racial difference in the relationship between total serum IgE and airway responsiveness that is unreported elsewhere. Overall, our results suggest that AA children may be predisposed to asthma.

The chest radiograph appearances of very premature infants at 36 weeks post-conceptional age

The chest radiograph of very premature infants at 36 weeks post-conceptional age (PCA) was evaluated with regard to the degree of hyperinflation and cardiomegaly, and the presence of fibrosis/interstitial shadowing, cystic elements, air bronchograms and opacification. The evolution of abnormalities was assessed by comparing the radiograph appearance at 36 weeks PCA with that at 28 days post-natal age (PNA). Three scoring systems were used to determine how any abnormalities present could be best quantified to reflect disease severity as determined by chronic dependency upon supplementary oxygen status. Chest radiographs at 36 weeks PCA from 60 infants (median gestational age 26 weeks (range 24-28)) were studied. 47 infants also had radiographs at 28 days PNA. Only three infants had no chest radiograph abnormalities at 36 weeks PCA, although 24 infants were not dependent upon supplementary oxygen. The most common abnormalities were interstitial shadowing and hyperinflation, while cystic elements and cardiomegaly were rare. The radiographic appearance had deteriorated from 28 days PNA to 36 weeks PCA (p < 0.05); more infants at 36 weeks PCA were hyperinflated (p < 0.01). The chest radiograph appearances of infants who were dependent upon supplementary oxygen scored higher than those who were not (p < 0.01) using all three scoring systems. The system that assessed only the presence of interstitial shadowing, cystic elements and hyperinflation had the highest specificity in identifying oxygen dependency beyond 36 weeks PCA and had the highest area under the respective receiver operator characteristic curve. In conclusion, the majority of very immature infants have an abnormal chest radiograph appearance at 36 weeks PCA. The appearance can, however, be meaningfully scored by evaluating only three abnormalities.

Population-based estimates of surfactant protein B deficiency

OBJECTIVE

Surfactant protein B deficiency is a lethal cause of respiratory distress in infancy that results most commonly from a homozygous frameshift mutation (121ins2). Using independent clinical ascertainment and molecular methods in different populations, we sought to determine allele frequency.

STUDY DESIGN

Using clinical characteristics of the phenotype of affected infants, we screened the Missouri linked birth-death database (n = 1 052 544) to ascertain potentially affected infants. We used molecular amplification and restriction enzyme digestion of DNA samples from a metropolitan New York birth cohort (n = 6599) to estimate allele frequency.

RESULTS

The point estimate and 95% confidence interval of the 121ins2 allele frequency in the Missouri cohort are 1/1000 individuals (.03-5.6/1000) and in the New York cohort are.15/1000 (. 08-.25/1000). These estimates are not statistically different.

CONCLUSIONS

The close approximation of these independent estimates suggests accurate gene frequency (approximately one 121ins2 mutation per 1000-3000 individuals) despite its rare occurrence and that this mutation does not account for the majority of full-term infants with lethal respiratory distress.