Very low birthweight and asthma by age seven years in a national cohort

Lung Function of Adults Born at Very Low Birth Weight

BACKGROUND

Much remains unknown about the consequences of very low birth weight (VLBW) and bronchopulmonary dysplasia (BPD) on adult lungs. We hypothesized that VLBW adults would have impaired lung function compared with controls, and those with a history of BPD would have worse lung function than those without.

METHODS

At age 26 to 30 years, 226 VLBW survivors of the New Zealand VLBW cohort and 100 term controls born in 1986 underwent lung function tests including spirometry, plethysmographic lung volumes, diffusing capacity of the lung for carbon monoxide, and single-breath nitrogen washout (SBN₂).

RESULTS

An obstructive spirometry pattern was identified in 35% VLBW subjects versus 14% controls, with the majority showing mild obstruction. Compared with controls, VLBW survivors demonstrated significantly lower forced expiratory volume in 1 second (FEV₁), FEV₁/forced vital capacity (FVC) ratio (FEV₁/FVC), forced expiratory flow at 25% to 75% of FVC and higher residual volume (RV), RV/total lung capacity (TLC) ratio (RV/TLC), decreased diffusing capacity of the lung for carbon monoxide, and increased phase III slope for SBN₂. The differences persisted after adjustment for sex and smoking status. Within the VLBW group, subjects with BPD showed significant reduction in FEV₁, FEV₁/FVC, and forced expiratory flow at 25% to 75% of FVC, and increase in RV, RV/TLC, and phase III slope for SBN₂, versus subjects without. The differences remained after adjustment for confounders.

CONCLUSIONS

Adult VLBW survivors showed a higher incidence of airflow obstruction, gas trapping, reduced gas exchange, and increased ventilatory inhomogeneity versus controls. The findings suggest pulmonary effects due to VLBW persist into adulthood, and BPD is a further insult on small airway function.

Respiratory morbidity through the first decade of life in a national cohort of children born extremely preterm

BACKGROUND

Advances in perinatal care have markedly increased the prospects of survival for infants born extremely preterm (EP). The aim of this study was to investigate hospitalisation rates and respiratory morbidity from five to 11 years of age in a prospective national cohort of EP children born in the surfactant era.

METHODS

This was a national prospective cohort study of all children born in Norway during 1999 and 2000 with gestational age (GA) < 28 weeks or birth weight < 1000 grams, and of individually matched term-born controls recruited for a regional subsample. Data on hospital admissions, respiratory symptoms, and use of asthma medication was obtained by parental questionnaires at 11 years of age.

RESULTS

Questionnaires were returned for 232/372 (62%) EP-born and 57/61 (93%) regional term-born controls. Throughout the study period, 67 (29%) EP-born and seven (13%) term-born controls were admitted to hospital (odds ratio (OR) 2.90, 95% confidence interval (CI): 1.25, 6.72). Admissions were mainly due to surgical procedures, with only 12% due to respiratory causes, and were not influenced by neonatal bronchopulmonary dysplasia (BPD) or low GA(≤ 25 weeks). Respiratory symptoms, asthma and use of asthma medication tended to be more common for EP-born, significantly so for medication use and wheeze on exercise. Neonatal BPD was a risk factor for medication use, but not for current wheeze. In multivariate regression models, home oxygen after discharge (OR 4.84, 95% CI: 1.38, 17.06) and parental asthma (OR 4.38, 95% CI: 1.69, 11.38) predicted current asthma, but neither BPD nor low GA were associated with respiratory symptoms at 11 years of age.

CONCLUSIONS

Hospitalisation rates five to 11 years after EP birth were low, but twice those of term-born controls, and unrelated to neonatal BPD and low GA. Respiratory causes were rare. Respiratory complaints were more common in children born EP, but the burden of symptoms had declined since early childhood.

Bronchopulmonary dysplasia as a risk factor for asthma in school children and adolescents: A systematic review

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that mainly affects extremely pre-term infants, and remains the most common complication of prematurity. Several studies have shown that prematurity predisposes to the development of asthma in school children and adolescents. Nevertheless, it is not clear to what extent a history of BPD involves an additional risk.

METHODS

A systematic review of studies assessing the association between BPD and asthma in school-children and adolescents was made. A literature search was carried out in the MEDLINE and EMBASE databases to retrieve articles published between 1 January 2000 and 31 August 2016.

RESULTS

A total of 17 studies comprising 7433 patients were included in the review. There was considerable heterogeneity in the definitions of BPD and asthma among studies. Overall, the prevalence of asthma was higher in children and adolescents with a history of prematurity and BPD compared with those who did not develop BPD. However, in only one of the studies did this difference reach statistical significance. The main limitation of this review was potential bias due to the lack of adjustment for confounding factors between exposure (BPD) and outcome (asthma) in most of the studies.

CONCLUSION

Based on the studies reviewed, it cannot be argued that BPD, as an independent factor of prematurity, increases the risk of asthma defined by clinical parameters in school-children and adolescents. Further studies of greater methodological quality and homogeneous diagnostic criteria of BPD and asthma are needed for improved assessment of this association.

Asthma related medication use and exacerbations in children and adolescents with type 1 diabetes

OBJECTIVES

To investigate the use of asthma medication and occurrence of asthma exacerbations up to 5 years before and after the onset of type 1 diabetes mellitus (T1DM) in children and adolescents.

METHODS

Children and adolescents younger than 19 years with at least 2 insulin prescriptions between 1999 and 2009 classified as T1DM cohort (n = 915) and a 4 times larger reference cohort (n = 3,590) with the same age and gender were identified from the Dutch PHARMO Record Linkage System. The date of first insulin dispensing was selected as the index date.

RESULTS

The 5-year prevalence rate of asthma medication use in the T1DM cohort (23.2%) was significantly higher than the reference cohort (18.3%) after the onset of diabetes. No statistically significant difference between the two cohorts was observed in the use of specific types of asthma medication except for short acting muscarinic antagonists that were significantly more used in the T1DM cohort (5.5%) compared with the reference cohort (0.62%) after the onset of diabetes. The incidence rate of asthma medication use declined over time with a peak in the T1DM cohort the 1st year after the onset of diabetes. Furthermore, 1 year after the index date there was a peak in incidence rate of asthma exacerbations in both T1DM (7.8 per 1,000 person year) and reference (6.8 per 1,000 person year) cohorts.

CONCLUSIONS

T1DM is associated with statistically significantly higher asthma medication use after the onset of T1DM, especially in the 1st year after the onset of diabetes. Pediatr Pulmonol. 2016;51:1113-1121. © 2016 Wiley Periodicals, Inc.

The New Zealand 1986 very low birth weight cohort as young adults: mapping the road ahead

Background

Very low birth weight (less than 1500 g) is associated with increased morbidity and costs of health care in childhood. Emerging evidence suggests these infants face a range of health and social problems as young adults. We studied all New Zealand very low birth weight infants born in 1986 (when 58 % were exposed to antenatal corticosteroids) in infancy, with later follow-up at 7 to 8 years and 23 to 24 years. We now aim to assess the cohort at 26–28 years compared with controls.

Methods/design

The case sample will comprise a minimum of 250 members of the 1986 New Zealand national very low birth weight cohort (77 % of survivors). Outcomes will be compared with a control group of 100 young adults born at term in 1986. Following written informed consent, participants will travel to Christchurch for 2 days of assessments undertaken by experienced staff. Medical assessments include growth measures, vision, respiratory function, blood pressure and echocardiogram, renal function, dental examination and blood tests. Cognitive and neuropsychological functioning will be assessed with standard tests, and mental health and social functioning by participant interview. A telephone interview will be conducted with a parent or significant other person nominated by the respondent to gain a further perspective on the young person’s health and functioning. All those born at less than 28 weeks’ gestation, plus a random subset of the cohort to a total of 150 cases and 50 controls, will be offered cranial magnetic-resonance imaging. Statistical analysis will examine comparison with controls and long-term trajectories for the very low birth weight cohort.

Discussion

The research will provide crucial New Zealand data on the young adult outcomes for very low birth weight infants and address gaps in the international literature, particularly regarding cardiovascular, respiratory, visual and neurocognitive outcomes. These data will inform future neonatal care, provide evidence-based guidelines for care of preterm graduates transitioning to adult care, and help shape health education and social policies for this high risk group.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12612000995875. Registered 1 October 2012

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0413-9) contains supplementary material, which is available to authorized users.

Psychosocial outcomes of young adults born very low birth weight

OBJECTIVE

To assess the early adult health, education, and social functioning of a national cohort of very low birth weight (VLBW) infants born in 1986 in New Zealand compared with a control group of young adults born the same year. The impact of neurodevelopmental disability at age 7 to 8 years on young adult outcomes was examined.

METHODS

Participants underwent a comprehensive face-to-face interview that included standardized assessment tools and previously used custom written survey items.

RESULTS

We interviewed 230 VLBW young adults (71% of survivors) and 69 controls at age 22 to 23 years. VLBW young adults were 5.6 kg lighter and 4.2 cm shorter than controls, had lower rates of tertiary education/training (percentage difference [95% confidence interval]: -13.1 [-21.6 to -1.8]) and university degree completion (-15.6 [-28.0 to -4.8]), had more often been welfare dependent (23.5 [10.2 to 35.0]), had few or no friends (20.5 [7.2 to 32.2]), and more often had wheeze in the past year (20.1 [9.0 to 28.6]). However, in many areas there were no differences between the VLBW cohort and controls, and VLBW adults rated their overall quality of life and behavioral functioning similarly to their peers. Those with previous disability had poorer social, occupational, and physical functioning than other VLBW young adults.

CONCLUSIONS

Despite some evidence of health, educational, and social difficulties, former VLBW young adults obtained similar scores across many aspects of health and social functioning as their same age peers, with some differences largely confined to those with previous disability.

Obesity and asthma

Asthma is a chronic disorder affecting millions of people worldwide. The prevalence of asthma is around 300 million and is expected to increase another 100 million by 2025. Obesity, on the other hand, also affects a large number of individuals. Overweight in adults is defined when body mass index (BMI) is between 25 to 30 kg/m(2) and obesity when the BMI >30 kg/m(2). It has been a matter of interest for researchers to find a relation between these two conditions. This knowledge will provide a new insight into the management of both conditions. At present, obese asthma patients may be considered a special category and it is important to assess the impact of management of obesity on asthma symptoms.

Pregnant Māori Smokers’ Perception of Cessation Support and How It Can Be More Helpful

This study aimed to investigate the perception of smoking cessation services and products by pregnant Māori (New Zealand's Indigenous people) smokers and identify how these can be improved. Semi-structured face-to-face interviews were conducted with 60 pregnant Māori smokers. Most of the women (82%) had been advised to stop smoking, but few (21%) felt influenced by the advice. In addition, the women in this study felt that health provider support needed to be more encouraging, understanding and more readily available. Many (78%) had come across smokefree pamphlets, but few had read them. Only four women had been given a booklet specifically aimed at pregnant Māori women. Several women thought that the promotion of smokefree pregnancies needed to be aimed at the whole whānau (extended family). The main conclusions were that motivation to quit could be enhanced by delivery of a clear, consistent and repeated message from multiple sources, backed up with effective, supportive and encouraging services and education resources about risks and smoking cessation options. Primary health care interventions delivering a range of services need to be flexible – for example, by visiting pregnant women in their home – and need to target the whole expectant whānau, instead of focusing on pregnant women in isolation.

Prenatal and passive smoke exposure and incidence of asthma and wheeze: systematic review and meta-analysis

OBJECTIVES

Exposure to passive smoke is a common and avoidable risk factor for wheeze and asthma in children. Substantial growth in the prospective cohort study evidence base provides an opportunity to generate new and more detailed estimates of the magnitude of the effect. A systematic review and meta-analysis was conducted to provide estimates of the prospective effect of smoking by parents or household members on the risk of wheeze and asthma at different stages of childhood.

METHODS

We systematically searched Medline, Embase, and conference abstracts to identify cohort studies of the incidence of asthma or wheeze in relation to exposure to prenatal or postnatal maternal, paternal, or household smoking in subjects aged up to 18 years old. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by using random effects model.

RESULTS

We identified 79 prospective studies. Exposure to pre- or postnatal passive smoke exposure was associated with a 30% to 70% increased risk of incident wheezing (strongest effect from postnatal maternal smoking on wheeze in children aged ≤2 years, OR = 1.70, 95% CI = 1.24-2.35, 4 studies) and a 21% to 85% increase in incident asthma (strongest effect from prenatal maternal smoking on asthma in children aged ≤2 years, OR = 1.85, 95% CI = 1.35-2.53, 5 studies).

CONCLUSIONS

Building upon previous findings, exposure to passive smoking increases the incidence of wheeze and asthma in children and young people by at least 20%. Preventing parental smoking is crucially important to the prevention of asthma.

Exploring modifiable risk factors for wheezing in African American premature infants

OBJECTIVE

To examine the degree to which obesity during infancy, consistent exposure to secondhand smoke, and parenting (positive attention, maternal involvement, and negative control) were related to early development of wheezing in a cohort of African American premature infants at 2, 6, 12, 18, and 24 months corrected age.

DESIGN

Secondary analysis of a subset of variables from a larger nursing support intervention study.

SETTING

Two regional perinatal centers in the southeastern United States.

PARTICIPANTS

One hundred and sixty-eight African American premature infants (70 boys, 98 girls) who weighed less than 1,750 g or required mechanical ventilation and their mothers.

METHODS

The presence of wheezing was obtained from maternal report at 2, 6, 12, 18, and 24 months. Infants were considered to have medically significant wheezing if they were using bronchodilators or pulmonary anti-inflammatory medications.

RESULTS

The percentage of infants who had medically significant wheezing increased from 12% at 2 months to 24% at 24 months corrected age. Infants who received more positive attention from their mothers had a slightly higher increase in the probability of developing wheezing over time. Infants of mothers who received public assistance had an increased probability of wheezing. Consistent exposure to secondhand smoke, obesity during infancy, maternal negative control, and maternal involvement were not related to the development of wheezing.

CONCLUSION

These findings suggest that the likelihood of developing wheezing in African American premature infants is associated with receiving more positive attention from their mothers and having mothers who receive public assistance. Because modifiable risk factors were not highly related to wheezing, intervention efforts need to focus on early identification and treatment of wheezing and asthma-related symptoms.

Determinants of the incidence of childhood asthma: a two-stage case-control study

Extensive literature exists on potential risk factors for childhood asthma. To the authors' knowledge, no investigators have yet attempted to disentangle the effects of those determinants within a single study setting. The authors aimed to evaluate the independent effects of 47 potential determinants (from the prenatal, perinatal, and childhood periods) of asthma development in children within the first 10 years of life. From a Canadian birth cohort of 26,265 children (1990-2002), a 2-stage case-control study was conducted. In the first stage, 20 controls per case were selected from 3 administrative databases. In the second stage, selected mothers were mailed questionnaires for assessment of additional determinants. Increased risks of childhood asthma were found for > or =1 previous diagnosis of bronchopulmonary disease and atopic dermatitis in the child, oxygen administration after birth, prescription of antibiotics within the first 6 months of life, male gender, asthma during pregnancy, use of antibiotics during pregnancy, maternal receipt of social aid, paternal asthma, and asthma in siblings. Protective effects included use of intranasal corticosteroids during pregnancy, having a wood-burning fireplace, having pets in the home prior to the index date, breastfeeding, and day-care attendance. This study allowed the authors to identify, within a single setting, the most influential determinants of childhood asthma among 47 predictors assessed for the prenatal, perinatal, and childhood periods.

Environmental exposures and respiratory morbidity among very low birth weight infants at 1 year of life

INTRODUCTION

Preterm infants have a substantially increased risk of developing respiratory illnesses. The goal of this study was to consider the impact of modifiable postnatal exposures on respiratory morbidity among a cohort of very low birth weight (VLBW) infants.

OBJECTIVES

(1) Assess the rates of respiratory morbidity and exposure to indoor respiratory triggers in a population of VLBW infants at 1 year; (2) determine the association between exposures and respiratory morbidity.

METHODS

We enrolled 124 VLBW infants into a prospective cohort study. Parents were called at 1 year to assess respiratory outcomes and environmental exposures. We used bivariate and multivariate analyses to assess the relationship between environmental exposures and acute care for respiratory illnesses.

RESULTS

At 1 year, 9% of infants had physician-diagnosed asthma, 47% required >or=1 acute visit and 11% required hospitalisation for respiratory illness. The majority of infants (82%) were exposed to at least one indoor respiratory trigger. Infants living with a smoker (61% vs 40%) and infants exposed to pests (62% vs 39%) were more likely than unexposed infants to require acute care for respiratory problems. In a multivariate regression controlling for demographics, birth weight, bronchopulmonary dysplasia, and family history of asthma or allergies, both living with a smoker (OR 2.62; CI 1.09 to 6.29) and exposure to pests (OR 4.41; CI 1.22 to 15.94) were independently associated with the need for acute care for respiratory illnesses.

CONCLUSIONS

In this sample, respiratory morbidity and exposure to triggers were common. VLBW infants may benefit from interventions that decrease exposure to respiratory triggers.

Environmental factors and allergic disorders

Despite numerous studies on possible associations between environmental exposure and allergic disorders, any conclusions made remain a matter of controversy. We conducted a review of evidence in relation to environmental and nutritional determinants and wheeze, asthma, atopic dermatitis, and allergic rhinitis. Identified were 263 articles for analysis after consideration of 1093 papers that were published since 2000 and selected by electronic search of the PubMed database using keywords relevant to epidemiological studies. Most were cross-sectional and case-control studies. Several prospective cohort studies revealed inconsistent associations between various environmental factors and the risk of any allergic disorder. Therefore, the evidence was inadequate to infer the presence or absence of a causal relationship between various environmental exposures and allergic diseases. However, evidence is suggestive of positive associations of allergies with heredity. Because almost all the studies were performed in Western countries, the application of these findings to people in other countries, including Japan, may not be appropriate. Further epidemiological information gained from population-based prospective cohort studies, in particular among Japanese together with other Asians, is needed to assess causal relationships between various environmental factors and allergic diseases.

Racial differences in the use of respiratory medications in premature infants after discharge from the neonatal intensive care unit

OBJECTIVE

To determine the effect of race and ethnicity on the use of oral beta-agonists, inhaled beta-agonists, and inhaled corticosteroids to treat respiratory symptoms in former premature infants after controlling for medical conditions, socioeconomic status, and site of outpatient care.

STUDY DESIGN

Using a population cohort of infants born at a gestational age < or = 34 weeks at 5 Northern California Kaiser Permanente hospitals between 1998 and 2001 (n = 1436), we constructed multivariable models to determine predictive factors for the receipt of respiratory medications during the first year after discharge.

RESULTS

After controlling for confounding factors, black infants were more likely to receive oral beta-agonists compared with white infants (OR 4.30, 95% CI 2.33-7.94), and Hispanic infants were less likely to receive inhaled beta-agonists (OR 0.62, 95% CI 0.39-0.99) or inhaled corticosteroids (OR 0.28, 95% CI 0.12-0.67). These findings were not explained by more outpatient visits for respiratory symptoms in black or Hispanic infants, because the observed racial differences persisted when children of similar respiratory symptoms were examined.

CONCLUSIONS

Even in a high-risk population of insured infants, substantial racial differences persist in the use of respiratory medications that could not be explained by differences in respiratory symptoms.

Low birthweight and asthma among young urban children

OBJECTIVES

We assessed whether the association between low birthweight and early childhood asthma can be explained by an extensive set of individual- and neighborhood-level measures.

METHODS

A population-based sample of children born in large US cities during 1998-2000 was followed from birth to age 3 years (N=1803). Associations between low birthweight and asthma diagnosis at age 3 years were estimated using multilevel models. Prenatal medical risk factors and behaviors, demographic and socioeconomic characteristics, and neighborhood characteristics were controlled.

RESULTS

Low-birthweight children were twice as likely as normal birthweight children to have an asthma diagnosis (34% vs 18%). The fully adjusted association (OR= 2.36; P<.001) was very similar to the unadjusted association (OR= 2.48; P<.001). Rates of renter-occupied housing and vacancies at the census tract-level were strong independent predictors of childhood asthma.

CONCLUSIONS

Very little of the association between low birthweight and asthma at age 3 can be explained by an extensive set of demographic, socioeconomic, medical, behavioral, and neighborhood characteristics. Associations between neighborhood housing characteristics and asthma diagnosis in early childhood need to be further explored.

Variation in childhood asthma among former preterm infants

OBJECTIVES

The role of in utero and perinatal exposures in modifying asthma risk among children born prematurely was assessed. Study design Former preterm children (n=251) were identified from a birth cohort. Examinations, including lung function testing, were performed at ages 8 to 11 years. Perinatal exposures were ascertained from neonatal medical records.

RESULTS

Univariate predictors of asthma included male gender, African American ethnicity, maternal asthma, and birth weight. Asthmatics were less likely to have been small for gestational age (SGA) than nonasthmatics (12.4% vs 22.7%, P=.04) and had more neonatal pulmonary disease. After adjusting for maternal asthma and demographic factors, asthma was associated with chronic lung disease of infancy, neonatal mechanical ventilation and corticosteroid use, and a higher childhood body mass index. Children who were septic postbirth and girls who were SGA were less likely to have asthma (OR for sepsis, 0.2; 95% CI, 0.1-0.6; OR for girls who were SGA compared with girls who were not SGA, 0.05; CI, 0.01-0.34).

CONCLUSIONS

Among premature children, female SGA status and neonatal sepsis appear protective relative to the development of childhood asthma. Differential susceptibility to asthma among preterm children may relate to exposures that operate in the in utero and early postnatal environment to accelerate lung development, alter innate immunity, or both.

Asthma, lung function and allergy in 12-year-old children with very low birth weight: a prospective study

We assessed the relationship between very low birth weight (VLBW) (<or=1500 g) and the development of asthma, lung function and atopy. The study groups comprised 74 of all 86 (86%) VLBW and 64 of all 86 (74%) matched term children who were prospectively followed for 12 years. A questionnaire on asthmatic and allergic symptoms was completed and skin prick tests, spirometry and hypertonic saline provocation tests were performed at 12 years of age. Cytokine secretion was analysed in stimulated blood leukocyte cultures in 28 VLBW and 23 term children. A history of asthma was more frequent among the VLBW children, as compared with the term children at age 12 (22% vs. 9%, p = 0.046). Among the VLBW children, very preterm birth (gestational age: week 25 to 29) (RR 2.5, 95%CI 1.1-5.8), neonatal mechanical ventilation (RR 2.8, 95%CI 1.2-6.4) and neonatal oxygen supplementation (RR 4.3, 95%CI 1.3-14.0) were significantly associated with a history of asthma by the age of 12 years in univariate analyses. In multivariate logistic regression, neonatal oxygen supplementation >or= 9 days was the only remaining significant risk factor for a history of asthma (adjusted OR 6.7, 95%CI 1.0-44). The VLBW children who required mechanical ventilation during the neonatal period were more likely to have bronchial hyperresponsiveness than those not requiring mechanical ventilation (60% vs. 28%, p = 0.050). The spirometric values were similar among the VLBW and the term children at 12 years. Very low birth weight was not significantly related to allergic rhinoconjunctivitis, eczema or positive skin prick tests. Furthermore, the levels of IL-4, IL-5 and IFN-gamma in stimulated cell cultures were similar in the VLBW and the term children. A history of asthma by 12 years of age was twice as common among the VLBW as the term children, and neonatal oxygen supplementation seemed to be associated with the increased risk. Furthermore, mechanical ventilation during the neonatal period was associated with bronchial hyperresponsiveness at age 12. Very low birth weight per se was not, however, related to atopy.