Respiratory symptoms in children of low birth weight

Spatial patterns and spatially-varying factors associated with childhood acute respiratory infection: data from Ethiopian demographic and health surveys (2005, 2011, and 2016)

BACKGROUND

In Ethiopia, acute respiratory infections (ARIs) are a leading cause of morbidity and mortality among children under five years. Geographically linked data analysis using nationally representative data is crucial to map spatial patterns of ARIs and identify spatially-varying factors of ARI. Therefore, this study aimed to investigate spatial patterns and spatially-varying factors of ARI in Ethiopia.

METHODS

Secondary data from the Ethiopian Demographic Health Survey (EDHS) of 2005, 2011, and 2016 were used. Kuldorff's spatial scan statistic using the Bernoulli model was used to identify spatial clusters with high or low ARI. Hot spot analysis was conducted using Getis-OrdGi statistics. Eigenvector spatial filtering regression model was carried out to identify spatial predictors of ARI.

RESULTS

Acute respiratory infection spatially clustered in 2011 and 2016 surveys year (Moran's I:-0.011621-0.334486). The magnitude of ARI decreased from 12.6% (95%, CI: 0.113-0.138) in 2005 to 6.6% (95% CI: 0.055-0.077) in 2016. Across the three surveys, clusters with a high prevalence of ARI were observed in the North part of Ethiopia. The spatial regression analysis revealed that the spatial patterns of ARI was significantly associated with using biomass fuel for cooking and children not initiating breastfeeding within 1-hour of birth. This correlation is strong in the Northern and some areas in the Western part of the country.

CONCLUSION

Overall there has been a considerable decrease in ARI, but this decline in ARI varied in some regions and districts between surveys. Biomass fuel and early initiation of breastfeeding were independent predictors of ARI. There is a need to prioritize children living in regions and districts with high ARI.

From neonatal lung function to lung function and respiratory morbidity at 6-year follow-up

BACKGROUND

Lung function is traceable from infancy to adulthood. Only a few studies have examined lung function from birth to childhood longitudinally in children born moderate to late preterm. We aimed to investigate how prematurity and lung function in the neonatal period are related to lung function and respiratory morbidity at age 6 in former moderate to late preterm children compared with children born at term.

METHODS

Lung function was measured in a cohort of moderately to late preterm (n = 48) and term-born (n = 53) infants in the neonatal period by FeNO, and tidal breathing flow-volume loops (TBFVL) and at age 6 (n = 52) by spirometry, whole-body plethysmograph and impulse oscillation combined with a respiratory symptom questionnaire.

RESULTS

Moderate to late preterm children had a higher T_PEF /T_E ratio neonatally (42.6% vs. 33.7%, p = 0.02) and a lower % predicted orced expiratory volume in the first second at age 6 (94.4% vs. 101.9%, p = 0.01) compared to term-born children. We found a significant association between the variability of neonatal tidal volume and effective airway resistance at age 6 (β = -0.34, p = 0.03). No association between neonatal FeNO or TBFVL and respiratory morbidity at 6-year follow-up was shown.

CONCLUSION

Children born moderate to late preterm had lower lung function at age 6 than term-born children. We did not find evidence for the use of neonatal tidal breathing parameters as a predictor for subsequent respiratory morbidity or lung function, however sample size was small.

Lifelong Lung Sequelae of Prematurity

The clinical, functional, and structural pattern of chronic lung disease of prematurity has changed enormously in last years, mirroring a better perinatal management and an increasing lung immaturity with the survival of increasingly premature infants. Respiratory symptoms and lung function impairment related to prematurity seem to improve over time, but premature birth increases the likelihood of lung function impairment in late childhood, predisposing to chronic obstructive pulmonary disease (COPD). It is mandatory to identify those individuals born premature who are at risk for developing long-term lung disease through a better awareness of physicians, the use of standardized CT imaging scores, and a more comprehensive periodic lung function evaluation. The aim of this narrative review was to provide a systematic approach to lifelong respiratory symptoms, lung function impairment, and lung structural anomalies in order to better understand the specific role of prematurity on lung health.

Influence of Severity of Type and Timing of Retrospectively Reported Childhood Maltreatment on Female Amygdala and Hippocampal Volume

Deleterious effects of adverse childhood experiences (ACE) on human brain volume are widely reported. First evidence points to differential effects of ACE on brain volume in terms of timing of ACE. Upcoming studies additionally point towards the impact of different types (i.e., neglect and abuse) of ACE in terms of timing. The current study aimed to investigate the correlation between retrospectively reported severity of type (i.e., the extent to which subjects were exposed to abuse and/or neglect, respectively) and timing of ACE on female brain volume in a sample of prolonged traumatized subjects. A female sample with ACE (N = 68) underwent structural magnetic resonance imaging and a structured interview exploring the severity of ACE from age 3 up to 17 using the “Maltreatment and Abuse Chronology of Exposure” (MACE). Random forest regression with conditional interference trees was applied to assess the impact of ACE severity as well as the severity of ACE type, (i.e. to what extent individuals were exposed to neglect and/or abuse) at certain ages on pre-defined regions of interest such as the amygdala, hippocampus, and anterior cingulate (ACC) volume. Analyses revealed differential type and timing-specific effects of ACE on stress sensitive brain structures: Amygdala and hippocampal volume were affected by ACE severity during a period covering preadolescence and early adolescence. Crucially, this effect was driven by the severity of neglect.

Pertussis Vaccination Failure in the New Zealand Pediatric Population: Study Protocol

Pertussis vaccines have been effective at reducing pertussis-associated morbidity and mortality. However, they have a complex array of limitations, particularly associated with the duration of protection against clinical disease and imperfect immunity (carriage and transmission). Little is known about risk factors for pertussis vaccination failure. Understanding pertussis vaccination failure risk is most important in the paediatric population. This study aims to investigate risk factors for pertussis vaccination failure in (1) infants between birth and six weeks of age born to mothers who received pertussis booster vaccinations during pregnancy and (2) infants after the completion of the primary series (approximately five months old) to four years old. This will be achieved in a two-step process for each study group. Pertussis vaccination failure cases will first be described using a case series study design, relevant case characteristics will be sourced from six national administrative datasets. The case series study results will help select candidate risk factors (hypothesis generating step) to be tested in the retrospective cohort study (hypothesis testing step. Pattern analysis will be used to investigate risk factor patterns in the cohort study. The identification of higher risk groups enables targeting strategies, such as additional doses, to better prevent pertussis disease.

Mora‐Faife E, García‐García G, del Valle‐Infante I, Gómez‐Marrero L, Britton J, Fogarty AW, HINASIC (Historia Natural de la Sibilancia en Cuba/Natural History of Wheezing in Cuba) Study Group. The association of low birth weight with serum C reactive protein in 3-year-old children living in Cuba: A population-based prospective study

OBJECTIVE

Low birthweight is associated with a decreased risk of childhood leukemia and an increased risk of both cardiovascular disease and all-cause mortality in adult life. Possible biological mediators include systemic innate immunity and inflammation. We tested the hypothesis that birthweight was inversely associated with serum high sensitivity C reactive protein assay (hsCRP), a measure of both innate immunity and systemic inflammation.

METHODS

Data on birthweight and current anthropometric measures along with a range of exposures were collected at 1 and 3 years of age in a population-based cohort study of young children living in Havana, Cuba. A total of 986 children aged 3-years-old provided blood samples that were analyzed for serum hsCRP levels.

RESULTS

Nearly 49% of children had detectable hsCRP levels in their serum. Lower birthweight was linearly associated with the natural log of hsCRP levels (beta coefficient -0.70 mg L-1 per kg increase in birthweight, 95% CI: -1.34 to -0.06). This was attenuated but still present after adjustment for the child's sex and municipality (-0.65 mg L-1 per kg birthweight; 95% CI: -1.38 to +0.08). There were no associations between growth from birth or anthropometric measures at 3 years and systemic inflammation.

CONCLUSIONS

Birthweight was inversely associated with serum hsCRP levels in children aged 3 years living in Cuba. These observations provide a potential mechanism that is present at the age of 3 years to explain the association between low birthweight and both decreased childhood leukemia and increased cardiovascular disease in adults.

Prevalence of asthma-like symptoms and assessment of lung function in schoolchildren born with low birth weight

INTRODUCTION

This study aimed to determine the prevalence of asthma-like symptoms among schoolchildren with low birth weight (LBW), and to compare the lung function of these children with that of children with normal birth weight.

METHODS

This was a comparative cross-sectional study. We recruited children aged 8-11 years from eight primary schools in Kota Bharu, Kelantan, Malaysia. The children were divided into two groups: those with LBW (< 2,500 g) and those with normal birth weight (≥ 2,500 g). Parents of the enrolled children were asked to complete a translated version of the International Study of Asthma and Allergies in Childhood questionnaire. Lung function tests, done using a MicroLoop Spirometer, were performed for the children in both groups by a single investigator who was blinded to the children's birth weight.

RESULTS

The prevalence of 'ever wheezed' among the children with LBW was 12.9%. This value was significantly higher than that of the children with normal birth weight (7.8%). Forced vital capacity (FVC), forced expiratory volume in one second, and forced expiratory flow when 50% and 75% of the FVC had been exhaled were significantly lower among the children with LBW as compared to the children with normal birth weight.

CONCLUSION

LBW is associated with an increased prevalence of asthma-like symptoms and impaired lung function indices later in life. Children born with LBW may need additional follow-up so that future respiratory problems can be detected early.

Respiratory function at age 8-9 after extremely low birthweight or preterm birth in Victoria in 1997

To determine if respiratory function at 8 years of age in extremely low birth weight (ELBW; birth weight <1,000 g) or extremely preterm (EPT, <28 weeks' gestation) children born in 1997 remains worse than normal birth weight (NBW; birth weight, >2,499 g) and term (37-42 weeks) controls, particularly in those ELBW/EPT children who had bronchopulmonary dysplasia (BPD). This was a cohort study of 201 consecutive ELBW/EPT survivors born in the state of Victoria during 1997, and 199 contemporaneous randomly selected NBW/term controls. Respiratory function was measured at 8 years of age according to standard guidelines, and compared with previous cohorts born in 1991-1992. Respiratory function data were available for almost 75% of both cohorts. ELBW/EPT subjects had substantial reductions in airflow compared with controls (e.g., mean difference in forced expiratory volume in 1 sec [FEV1 ] -0.91 SD, 95% confidence interval [CI] -1.19 to -0.63 SD, and in maximum expiratory flow between 25% and 75% of vital capacity [FEF25-75% ] -0.96 SD, 95% CI -1.22 to -0.71). These differences were similar to those observed between ELBW/EPT and controls subjects born in 1991-1992. Within the ELBW/EPT cohort, children who had BPD in the newborn period had significant reductions in both the FEV1 (-0.76 SD) and FEF25-75% (-0.58 SD) compared with those who did not have BPD, which were not statistically significant from those in the 1991-92 cohort. ELBW/EPT children born in 1997 still have significantly abnormal lung function compared with NBW/term controls, but results were similar to an earlier era when survival rates were lower. Pediatr Pulmonol. 2013; 48:449-455. © 2012 Wiley Periodicals, Inc.

Exercise-induced bronchoconstriction in school-age children born extremely preterm

BACKGROUND

School children born preterm often show airway hyperresponsiveness to methacholine or histamine. Less attention has been paid to their airway response to exercise, an important point because of the role of exercise in the child's daily life. The aim of this study was to describe the characteristics of, and potential determinants to, the airway response to exercise in children born extremely preterm.

METHODS

Forty-two nonasthmatic nonatopic children born before 32 wk gestation were compared with 27 healthy nonasthmatic nonatopic term children at age 7. Spirometry and respiratory impedance were measured at baseline and repeated after a single-step 6-min treadmill exercise in a climate-controlled room.

RESULTS

The preterm group showed significant broncho-constriction induced by exercise. Prematurity, but not low baseline lung function, neonatal oxygen supplementation, mechanical ventilation, chronic lung disease, or maternal smoking, was a determinant of exercise-induced bronchoconstriction.

CONCLUSION

Children born extremely preterm present significant exercise-induced airway obstruction at age 7. The response has different characteristics from that occurring in asthmatics and is likely to express airway noneosinophilic inflammation.

Early origins of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and a significant challenge for adult physicians. However, there is a misconception that COPD is a disease of only adult smokers. There is a growing body of evidence to support the hypothesis that chronic respiratory diseases such as COPD have their origins in early life. In particular, adverse maternal factors will interact with the environment in a susceptible host promoting altered lung growth and development antenatally and in early childhood. Subsequent lung injury and further gene-environment interactions may result in permanent lung injury manifest by airway obstruction predisposing to COPD. This review will discuss the currently available data regarding risk factors in early life and their role in determining the COPD phenotype.

Preterm birth and respiratory disease in later life

Chronic respiratory diseases are a common complication of preterm birth, particularly among very immature infants or those suffering from bronchopulmonary dysplasia. Major progress in the treatment of preterm newborns has changed the pattern of late respiratory complications. The major respiratory problem in infancy and early childhood is respiratory exacerbations caused by infections (particularly viral ones), which need hospitalization. The symptoms become mild in school-age children; however, a group of children still present with chronic airway obstruction defined by recurrent episodes of wheezing and decreased lung function tests (decreased forced expiratory volume). For some preterm infants, particularly those with bronchopulmonary dysplasia, obstructive lung disease persists into adulthood. They are very likely to develop chronic obstructive pulmonary disease or similar disease later in life. In these patients, a program of lung function monitoring and pulmonary prophylaxis by means of elimination of specific risk factors in adulthood is advisable.

Review Series: What goes around, comes around: childhood influences on later lung health?: Long-term follow-up of infants with lung disease of prematurity

The incidence of live preterm birth is increasing and concomitantly the survival of preterm babies has increased over the last 30 years due to advances in neonatal care. Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease that develops as a consequence of perinatal and/or neonatal lung injury following preterm birth and the pathology has also changed with changes in neonatal care. There are data suggesting that there is increased respiratory morbidity of ex-preterm subjects in childhood. It is only now that large populations of preterm subjects are reaching adulthood and may be at risk of persistent respiratory morbidity. This review will summarize the current knowledge in adulthood of respiratory sequelae following preterm birth; specifically it will review respiratory symptoms, pulmonary function, exercise capacity and structural lung disease as determined by high resolution computed tomography scans in ex-preterm survivors with and without BPD. Whether prematurity-related lung disease is associated with chronic obstructive airways disease will be discussed.

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.

Prenatal risk factors and occurrence of allergic rhinitis among elementary school children in an urban city

OBJECTIVES

To investigate the incidence and prenatal risk factors for allergic rhinitis among elementary school children in an urban city.

STUDY DESIGN

Risk factor data were collected by questionnaire and direct physical examination. Multiple logistic regression analysis was used to calculate the odds ratios of developing allergic rhinitis among children 6-13 years of age.

METHODS

From January 2006 to December 2006, we enrolled 1368 elementary school children in the study. Sampling was done by a multi-stage clustered-stratified random method to determine the study subject. All the children studied attended 12 elementary schools located in the six districts in Taipei, with two schools in each district. Odds ratios were adjusted for the confounding effects of gender, parity, maternal age at childbirth, maternal education, gestational complications, tobacco smokers in the residence, pets, carpets, molds, and air pollution.

RESULTS

The incidence of allergic rhinitis in the study was 50.1% (685/1368). Factors like gender (p<.001), parity (p<.05), carpets (p<.025), and air pollution (p<.001) increased risk, while the other factors did not (p>.05 for all).

CONCLUSION

Gender, parity, carpets, and air pollution increased the risk of developing allergic rhinitis among elementary school children. Other potential factors such as low birth weight, maternal age at childbirth, parental education, gestational complications, presence of tobacco smokers, and exposure to pets and molds did not significantly increase risk of developing allergic rhinitis.

Is the association between low birth weight and asthma independent of genetic and shared environmental factors?

Epidemiologic evidence linking birth weight and asthma is inconsistent. The authors examined the association between birth weight and asthma during childhood and adult life in twins. Using prospectively collected data on 21,588 like-sexed Swedish twins of known zygosity born in 1928-1952, they first conducted a cohort study to examine the risk of asthma in relation to birth weight. Next, they conducted nested co-twin control analyses among 643 dizygotic and 365 monozygotic twin pairs discordant for asthma to ascertain whether the association between birth weight and asthma could be confounded by genetic and shared environmental exposures. In the cohort analysis, birth weight of <2,500 g was associated with significantly greater risk of asthma independent of perinatal characteristics and within-twin-pair correlations. In the co-twin control analyses, birth weight of <2,500 g was significantly related to increased risk of asthma among monozygotic twins (relative risk for 2,000 g vs. 2,500 g = 1.58, 95% confidence interval: 1.06, 2.38). A negative association between birth weight and asthma, albeit not statistically significant, was also found among dizygotic twins. In conclusion, there is a negative association between birth weight and asthma in twins that is unlikely to be confounded by genetic or shared environmental factors.

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.

Longitudinal evaluation of airway function 21 years after preterm birth

RATIONALE

There are limited longitudinal data about respiratory morbidity and lung function after preterm birth into adulthood.

OBJECTIVES

To determine the evolution of respiratory symptoms, spirometry, and airway hyperresponsiveness of ex-preterm subjects from childhood into adulthood.

METHODS

Ex-preterm subjects (median birth weight, 1,440 g; median gestation, 31.5 wk), recruited at birth (not treated with surfactant), had excess respiratory symptoms, airway obstruction, and increased airway hyperresponsiveness in mid-childhood. At a median age of 21.7 years, 60 of these subjects (the index study group) and 50 healthy term control subjects were recruited to determine respiratory morbidity and spirometry.

MEASUREMENTS AND MAIN RESULTS

Respiratory symptom questionnaire, spirometry, and methacholine challenge test. The index study group had significantly more respiratory symptoms (16 of 60) than did control subjects (4 of 50) (odds ratio, 4.2; 95% confidence interval, 1.3 to 13.5; P = 0.01), but no significant difference in measured spirometry. Specifically, in the index study group and control subjects, the mean z scores (95% confidence interval of the group difference) for the FEV(1) were -0.60 and -0.58 (-0.44 to 0.49), respectively (P = 0.92); for the forced mid-expiratory flow they were -1.02 and -0.86 (-0.33 to 0.64), respectively (P = 0.52); and for the FVC they were -0.29 and -0.33 (-0.46 to 0.38), respectively (P = 0.85). Ex-preterm adults did not show evidence of increased airway hyperresponsiveness compared with control subjects, 23 and 19%, respectively (P = 0.89).

CONCLUSIONS

There are still excess respiratory symptoms 21 years after preterm birth. Reassuringly, this longitudinal study did not show evidence of persistent airway obstruction or airway hyperresponsiveness in ex-preterm adults.

Very prematurely born infants wheezing at follow-up: lung function and risk factors

OBJECTIVES

To determine whether abnormalities of lung volume and/or airway function were associated with wheeze at follow-up in infants born very prematurely and to identify risk factors for wheeze.

DESIGN

Lung function data obtained at 1 year of age were collated from two cohorts of infants recruited into the UKOS and an RSV study, respectively.

SETTING

Infant pulmonary function laboratory.

PATIENTS

111 infants (mean gestational age 26.3 (SD 1.6) weeks).

INTERVENTIONS

Lung function measurements at 1 year of age corrected for gestational age at birth. Diary cards and respiratory questionnaires were completed to document wheeze.

MAIN OUTCOME MEASURES

Functional residual capacity (FRC(pleth) and FRC(He)), airways resistance (R(aw)), FRC(He):FRC(pleth) and tidal breathing parameters (T(PTEF):T(E)).

RESULTS

The 60 infants who wheezed at follow-up had significantly lower mean FRC(He), FRC(He):FRC(pleth) and T(PTEF):T(E), but higher mean R(aw) than the 51 without wheeze. Regression analysis demonstrated that gestational age, length at assessment, family history of atopy and a low FRC(He):FRC(pleth) were significantly associated with wheeze.

CONCLUSIONS

Wheeze at follow-up in very prematurely born infants is associated with gas trapping, suggesting abnormalities of the small airways.

Airway function measurements and the long-term follow-up of survivors of preterm birth with and without chronic lung disease

This seventh paper in a review series on different aspects of chronic lung disease following preterm birth focuses on the current knowledge of respiratory symptoms, airway function, airway hyperresponsiveness, and exercise capacity from childhood to adulthood. This paper further considers the long-term implications of these studies for both future research and clinical practice.

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.

Respiratory symptoms and lung function in relation to atopy in children born preterm

Respiratory morbidity is a major health problem among children. The aim of this study was to compare the background of respiratory problems of children born preterm with that of children born full-term, with special reference to atopy. The study comprised two cohorts of 10-year-old children: a group of 72 children born preterm with birth weights of less than 1,501 g, and a group of 65 children born full-term with birth weights of over 2,500 g. Histories of respiratory and atopic symptoms, and of risk factors for atopy, were collected with a questionnaire. Predisposition to atopy was verified by skin-prick testing and by measuring serum total and antigen-specific IgEs. Lung function was evaluated by spirometry testing. Children born preterm had significantly more wheezing. In them, the lifetime prevalence of wheezing was 43%, vs. 17% in children born full-term (P = 0.001; odds ratio, 3.71; 95% confidence interval, 1.67-8.25). In the full-term group, wheezing was associated with atopy: 64% of wheezers were atopic; in the preterm group, 23% of wheezers were atopic (difference between groups, P = 0.024). Children born preterm expired significantly lower spirometry values of forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), FEV1/FVC ratio, forced expiratory flow after 50% of vital capacity has been exhaled (FEF50), and forced expiratory flow during middle half of FVC (FEF25-75). In the preterm group, wheezing, asthma, and low gestational age, but not atopy, were significantly associated with lower lung function values. Wheezers of the preterm group who still wheezed at age 10 were significantly more often atopic than those who no longer wheezed (62% vs. 9%, P = 0.006). In conclusion, we demonstrated a significant difference between groups in the association of atopy with respiratory problems. However, although atopy was not associated with a lifetime prevalence of respiratory symptoms in prematurely born children, an atopic predisposition in them was found to associate with persistence of wheezing.

Prevention of atopic disorders

Prevention of sensitization, onset of disease and disease exacerbations is a very important aspect of holistic approach towards allergic disorders. The prevalence of allergic or atopic disorders has increased significantly in children over the last three decades. There are significant variations in prevalence between countries and also within many countries. Environmental factors obviously play a major role. Environmental allergens are responsible for sensitisation, disease and exacerbations of disease symptoms. Preventive strategies at each level are important: Primary prevention is to stop the process of sensitisation and secondary prevention to prevent re-exposures or prolonged exposure in those who have become sensitized while tertiary prevention is to reduce or minimise morbidity. Various allergen avoidance measures are discussed, with reference to India so that physicians can incorporate these in the management not only of atopic patients but also as preventive strategy in high risk families.

Childhood asthma: causes, epidemiological factors and complications

Asthma is common in children and its prevalence in this age group is increasing. While the reasons for this reported increase, and indeed the true magnitude of the increase, remain unclear, there can be no doubt that asthma is now a major health problem in children worldwide. Fortunately, our knowledge of the pathophysiology of asthma is also increasing. It is now known that asthma is a chronic inflammatory disease regulated by a variety of mediators, of which perhaps the leukotrienes are among the most important. This new understanding of the pathophysiology of the disease has spurred the development of the antileukotriene agents, which can be expected to play an increasingly important role in the management of childhood asthma.

Measuring respiratory outcome

Chronic respiratory morbidity is a common outcome of very premature birth. Infants who are chronically oxygen dependent with an abnormal chest radiograph are described as suffering from chronic lung disease (CLD), and those with the worst abnormalities diagnosed as having bronchopulmonary dysplasia. CLD infants are very likely to be readmitted to hospital during infancy, particularly during a respiratory syncytial virus (RSV) epidemic. Very low birthweight, prematurity and CLD are associated with recurrent respiratory symptoms and lung function abnormalities during the preschool years. These problems are detected even in adolescents who were chronically oxygen dependent after premature birth. Further research to identify effective preventative strategies is urgently required.

The effect of parental smoking on presence of wheez or airway hyper-responsiveness in New South Wales school children

BACKGROUND AND AIMS

To assess accurately the effect of parental smoking on the respiratory health of New South Wales (NSW) school children, we obtained a large data set by pooling data from seven cross-sectional studies conducted in NSW between 1991 and 1993.

METHODS

A random sample of 6394 children age eight to 11 years was studied. Respiratory symptoms, family history of asthma and parental smoking history were measured by questionnaire, atopy by skin prick test and airway hyper-responsiveness (AHR) by histamine inhalation test.

RESULTS

In total, 58.3% of children had at least one parent who smoked; 38.5% were exposed to maternal smoking. After adjusting for potential confounders, such as atopy, parental history of asthma and bronchitis in the first two years, children who were exposed to maternal smoking had a significantly increased risk of recent wheeze but not of AHR (odds ratios 1.33; 95% CI: 1.2-1.5 and 1.00; 95% CI: 0.9-1.2).

CONCLUSIONS

The positive association with wheeze and the lack of an association with AHR suggests that exposure to parental smoking leads to wheezing, but does not increase airway responsiveness.

Asthma: a longitudinal perspective

In the future, the important longitudinal studies will be those that divide the broad spectrum of asthma into phenotypic groups in order to provide more precise information about mechanisms and outcomes. Asthmatics who present in a clinical setting often have a combination of two or three different phenotypes, and may have more severe illness as a result, but subjects who are tested in epidemiological studies are frequently characterized by only one phenotype. Although the definition of asthma as a combination of symptoms plus either AHR or reduced lung function has greater predictive isolation for assessing the prognosis of respiratory illness that occurs in childhood (27,40,55,66-68), studies that are able to classify subjects according to their different phenotypes are more likely to lead to a better understanding of the factors that influence prognosis. More importantly, by using this approach, future research studies should be better able to separate the mechanisms whereby therapeutic or environmental interventions influence the prognosis of each phenotype. The potential benefits will be a better understanding and evaluation of the factors that make an important contribution to respiratory health.

Asthma in adult life--is there an association with birth weight?

OBJECTIVE

To determine whether birth weight is associated with asthmatic disorders in adult life.

DESIGN

A case-control study which compared birth weight and other indicators of pregnancy outcome in a group of adult asthmatic patients and in matched healthy controls. The diagnosis of asthma was verified using defined criteria. All asthmatic subjects were excluded from the control group.

SETTING

Four primary health care centres in Lund, Sweden.

SUBJECTS

55 asthma patients and 92 healthy controls, all born between 1948 and 1973 in Lund.

MAIN OUTCOME MEASURES

Birth weight, birth height, head circumference, placental weight, and gestational age. Data from a self-administered questionnaire on social and medical background factors including smoking, educational level, and a self-reported history of frequent severe respiratory infections in childhood.

RESULTS

No significant differences were found between asthma patients and controls in birth weight, 3529 (SD 533) g versus 3536 (501) g, or in other variables associated with pregnancy outcome. There were no differences in current smoking habits or in educational level between the groups. The asthma patients, however, reported a higher number of childhood respiratory infections (p < 0.001) than the controls.

CONCLUSIONS

These epidemiological findings do not lend support to the hypothesis that a reduced birth weight is associated with a "programming" factor for asthma. Environmental factors in childhood seem more important than fetal malnutrition for the development of asthma in adult life.

Asthma prevalence and risk factors in selected Head Start sites in Chicago

Prevalence of and risk factors for asthma were examined in 1085 Head Start families at 18 Head Start sites in four high-risk community areas in 1994. A total of 13.9% of the families reported diagnosed asthma in their Head Start child and 18.8% reported that their child wheezed in the last 12 months. A total of 26.9% of respondents reported asthma in the immediate family of the child. Low birth weight (1500-2499 g), very low birth weight (<1500 g), and self-reported exposure to dampness or mold in the last 12 months were significantly associated with self-reported diagnosed asthma (OR = 1.93; 95% CI 1.17-8.73), (OR = 4.5; 95% CI 1.25-16.3), and (OR = 1.94; 95% CI 1.23-3.04), respectively. The young age of the children in Head Start, as well as the high prevalence of asthma in their families, suggest that the Head Start programs offer an unusual opportunity for asthma prevention programs.

Respiratory health, lung function, and airway responsiveness in school-age survivors of very-low-birth-weight

The purpose of this study was to determine the respiratory symptoms, pulmonary function, and airway reactivity in school-age survivors of very-low-birth-weight and to describe the influence of birth weight and perinatal illness on their pulmonary function. Thirty (of 39) 10- to 11-year-old survivors of very-low-birth-weight (VLBW) recruited at birth into a prospective longitudinal study of development; 30 (of 32) normal-birth-weight peers recruited from the same school or census tract as the VLBW group at age 5; and 15 normal-birth-weight siblings of the VLBW group participated in the study. Outcome measures were mother's reports of respiratory health; forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1); FEV1/FVC; forced expiratory flow, midexpiratory phase (FEF25-75); peak expiratory flow rate (PEFR); and tolerance to methacholine. There were no differences between groups in mothers' reports of current respiratory health. Pulmonary function values were lower for the VLBW survivors but significant only for FEF25-75 (F = 4.13; P = 0.02). Number of days in the intensive care nursery correlated significantly with decreased FEV1 (r = -.40, df = 28, P = 0.03), FEV1/FVC (r = -.37, df = 28, P = 0.04, and FEF25-75 (r = -.39, df = 28, P = 0.03). Only the relationship between length of nursery stay and FEV1/FVC was independent of birth weight. Number of days on mechanical ventilation was significantly correlated with decreased FEV1 (-.44, df = 28, P = 0.01), FEV1/FVC (r = -.38, df = 28, P = 0.04), FEF25-75 (r = -.44, df = 28, P = 0.01, and PEFR (r = -.40, df = 28, P = 0.03). All of these relationships were independent of birth weight. There were no significant associations between perinatal risk factors and methacholine responsiveness. Differences between VLBW children and normal-birth-weight children in pulmonary function are modest even when statistically significant. Severity of perinatal illness influences pulmonary function parameters into late childhood.

Effect of pneumonia and whooping cough in childhood on adult lung function

BACKGROUND

Previous studies have suggested that respiratory infection during childhood is associated with respiratory disease in adulthood, but the link is unclear because of retrospective ascertainment of childhood infection, selection bias, and confounding factors.

METHODS

We studied the effects of childhood pneumonia and whooping cough in 1392 British adults followed from birth in 1958. Of these, 193 had a history of pneumonia and 215 a history of whooping cough by the age of seven years. When the subjects were 34 or 35 years old, their forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured before and after they inhaled albuterol.

RESULTS

A history of pneumonia was associated with deficits (+/-95 percent confidence limits) in both FEV1 (102+/-73 ml, P=0.006) and FVC (173+/-70 ml, P=0.001) when the analysis was adjusted for sex, height, and smoking, with no change in the ratio of FEV1 to FVC. These deficits persisted after inhalation of albuterol. In subjects with no history of wheezing, the deficit in FEV1 was 155+/-122 ml (P=0.01), in those with past wheezing it was 41+/-128 ml (P=0.53), and in those with current wheezing it was 119+/-133 ml (P=0.08). The effect was no greater for the subjects who had pneumonia at less than two years of age than for those who had it between the ages of two and seven years and was not diminished after control for multiple confounding factors. The deficits associated with whooping cough were smaller (FEV1, 41+/-70 ml; P=0.25; FVC, 81+/-76 ml; P=0.04).

CONCLUSIONS

Childhood pneumonia is associated with reduced ventilatory function in adults. This reduction is independent of a history of wheezing and is not explained by other confounding factors.

Evaluation of criteria for chronic lung disease in surviving very low birth weight infants. Newborn Lung Project

Criteria in common use for the diagnosis of chronic lung disease of prematurity or bronchopulmonary dysplasia in the neonatal period have not been sufficiently compared and validated against indicators of later respiratory complications. In this study of all 680 infants < or = 1500 gm birth weight admitted to six perinatal centers August 1, 1988, to July 31, 1990, 524 were alive and had no major congenital anomalies at 5 years old. Of 419 who had given permission to release their names and addresses, 272 were located and participated in a follow-up study. The following diagnostic criteria for bronchopulmonary dysplasia and chronic lung disease of prematurity were used during the initial hospitalization: (1) use of supplemental oxygen on day 30 of life, (2) a comprehensive bronchopulmonary dysplasia severity score applied at 25 to 35 days of life developed by a clinician panel to adjust for practice variation in ventilatory support and blood gases, (3) use of supplemental oxygen on day 30 of life with radiographic evidence consistent with bronchopulmonary dysplasia between days 25 and 35 of life, (4) radiographic evidence consistent with bronchopulmonary dysplasia alone, and (5) use of supplemental oxygen at 36 weeks' postconceptional age. These criteria were assessed against use of bronchodilators or steroids during the first 2 years of life, diagnosis of asthma, and hospitalizations for respiratory causes up to age 5. Although all criteria were significantly associated with all the outcomes, radiographic evidence was most predictive. These results indicate that, during a period when 21% of neonates were exposed to antenatal steroids, 24% received surfactant and 9% received postnatal corticosteroids, radiographic evidence was more predictive of long-term respiratory outcome than other commonly used criteria.

Glutathione and neonatal lung disease

Glutathione (GSH) was measured using HPLC-electrochemical detection in bronchoalveolar lavage fluid from 28 neonates for up to 21 days after birth. GSH levels varied from 0.1-11.2 mumol l-1 (with a geometric mean concentration of 1.3 mumol l-1). GSH in epithelial lining fluid was estimated using the urea dilution method at 15.0 mumol l-1 (range 0.5-196 mumol l-1), which is significantly lower than observed in adult subjects. There was an L shaped relationship between GSH and the two markers of oxygen therapy, oxygen index and FiO2. The lowest GSH levels were associated with the group of infants with the most severe airways problems who required high oxygen.

Weight gain during the first year of life in relation to maternal smoking and breast feeding in Norway

OBJECTIVE

To assess the weight gain during the first year of life in relation to maternal smoking during pregnancy and the duration of breastfeeding.

DESIGN

This was a one year cohort study.

SETTING

The city of Oslo, Norway.

PARTICIPANTS

Altogether 3020 children born in Oslo in 1992-93. Children were divided into three groups as follows: 2208 born to non-smoking mothers, 451 to mothers who were light smokers (< 10 cigarettes per day), and 261 to mothers who were heavy smokers (> or = 10 cigarettes per day).

MAIN RESULTS

The mean birth weights were 3616 g, 3526 g, and 3382 g and 1 year body weights were 10,056 g (gain 6440 g per year), 10,141 g (6615 g), and 10,158 g (6776 g) in children of non-smoking and light and heavy smoking mothers respectively. Cox regression analysis showed that children of heavy smokers were 2.0 (95% confidence interval, 1.7, 2.3) times and children of light smokers 1.3 (1.2, 1.5) times more likely to have stopped breast feeding during their first year of life compared with children whose mothers were non-smokers. Linear regression analysis, adjusting for confounders, showed that weight gain was slower in breast fed children than in those who were not breast fed (-38 g (-50, -27) per month of breast feeding). Compared with children of non-smokers, the adjusted weight gain was 147 g (40, 255) per year greater in children of light smokers and 184 g (44, 324) per year in children of heavy smokers.

CONCLUSION

Children catch up any losses in birth weight due to maternal smoking, but some of the catch up effect is caused by a shorter duration of breast feeding in children of smoking mothers.

Respiratory morbidity in preschool children born prematurely. Relationship to adverse neonatal events

Respiratory morbidity, recurrent cough and/or wheeze and lung function abnormalities are common even outside infancy in preschool children born prematurely. Throughout the first 5 years of life, adverse neonatal events such as immaturity at birth and a requirement for prolonged respiratory support are significantly associated with positive symptom status. In the older preschool child, however, there is some evidence to suggest that other factors, such as a family history of atopy, may be equally important. The development of recurrent symptoms even at 4 years of age can be predicted accurately from the results of lung function measurements made in infancy, and hopefully such data will facilitate the introduction of effective intervention strategies. Lung function abnormalities are more marked in symptomatic patients and, in older children, seem to reflect increased airway responsiveness rather than having a significant relationship to adverse neonatal events. The hospital readmission rate for respiratory disorders, however, is certainly adversely affected by extremely low birthweight and neonatal chronic lung disease, as well as current symptom status. These data highlight that strategies to reduce extremely premature delivery and its consequences should favourably influence respiratory morbidity in preschool children.

Recurrent wheezing in very preterm infants

AIMS

To document the prevalence of, and identify risk factors for, recurrent wheezing treated with bronchodilators in the first year of life.

METHODS

Parental history and neonatal data were collected prospectively in a regional cohort of very preterm infants (< 33 weeks). Data on maternal smoking, siblings at home, breast feeding, respiratory symptoms, and hospital re-admissions were documented at 12 months.

RESULTS

Outcome data were available for 525/560 (95%) of survivors. The incidence of recurrent wheeze was 76/525 (14.5%) in very preterm infants and 20/657 (3%) in a cohort of term newborns. Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma, maternal smoking, siblings at home, neonatal oxygen supplementation at 28 days, 36, and 40 weeks of gestation.

CONCLUSIONS

Wheezing respiratory illnesses are common in very preterm infants. The factors involved are similar to those in more mature infants, with the addition of immaturity and neonatal lung injury.

Respiratory health in a total very low birthweight cohort and their classroom controls

AIMS

To compare the respiratory health and function at 8 to 9 years of age of a total population based cohort of 300 very low birthweight (VLBW) children with that of two classroom controls (n = 590) matched for age and sex.

STUDY DESIGN

Cohort study with controls.

SETTING

Schools throughout Scotland.

RESULTS

The VLBW children were more likely than their peers to use an inhaler, to be absent from school, and to be admitted to hospital because of respiratory illness. They were significantly shorter than their classroom controls, but even after adjusting for differences in height, the VLBW children had reduced forced vital capacity (FVC); this was associated with a history of prolonged ventilation (> 28 days) and pneumothorax in the neonatal period. There were no significant differences between the groups in forced expiratory volume in one second (FEV1)/FVC but twice as many (7.9% v 3.7%) of the VLBW children had ratios < 70%, denoting obstructive airways disease. Poor expiratory function was associated with neonatal respiratory distress syndrome, prolonged ventilation, and the need for > 40% oxygen. Exercise induced airway narrowing was increased in VLBW children (odds ratio = 2.0; 95% confidence interval 1.2 to 3.4) and was very little changed by adjustment for inhaler use and exposure to cigarette smoke.

CONCLUSIONS

As in other low birthweight cohorts, respiratory morbidity was increased. Unlike previous studies, FVC was more affected than expiratory function in this VLBW population. Our findings support the hypothesis that poorer lung function is associated with very low birth weight, but not with intrauterine growth retardation.

Neonatal characteristics as risk factors for preschool asthma

Childhood asthma usually begins early in life. Neonatal characteristics are reportedly predictive of symptom onset. This investigation utilized data from a provincial health organization to evaluate the effect of several birth characteristics on asthma incidence and hospitalization for asthma during age 0-4. Using logistic regression, the odds ratios (OR) for the following variables indicate a significant (p < 0.05) association with physician-diagnosed preschool asthma: male gender (OR = 1.72), birthweight < 1500 g (OR = 2.11), prematurity (OR = 1.34), respiratory distress syndrome (RDS) in the presence (OR = 2.95) or absence (OR = 1.61) of bronchopulmonary dysplasia (BPD), and transient tachypnea of the newborn (TTN; OR = 1.36). Male gender (OR = 1.91), birthweight < 1500 g (OR = 2.56), RDS with and without BPD (OR = 3.35 and 2.50, respectively), TTN (OR = 2.08), and severe birth asphyxia (OR = 1.94) showed an important association with hospitalization due to asthma. Neonatal characteristics are important determinants for the risk of preschool asthma, even after mutual adjustment.

Progression of allergy and asthma through childhood to adolescence

The reduction in asthma symptoms and bronchial hyperresponsiveness in adolescence is not well understood. Nor can the differences in asthma prevalence and severity between the sexes, which reverse at puberty, be explained. It has been suggested that the improvement in asthma during adolescence may result from diminished clinical and immunological responsiveness directly related to hormonal changes and that the effect of age on the prevalence of asthma in each sex may relate to differences in hormonal status, potentially influencing airway size, inflammation, and smooth muscle and vascular functions. However, few comprehensive studies are available. In summary, all wheezing is not asthma. Non-asthmatic wheezing illnesses may in part be attributable to anatomical abnormalities of the lung (transient early wheezing, premature birth). Little is known about the genetic and environmental determinants of childhood asthma, and factors related to the development of atopic sensitisation, such as exposure to allergens, infectious diseases, or tobacco smoke early in life, and dietary habits may be important, whereas the relevance of air pollution remains to be established. Unfortunately, we still do not know how to prevent the manifestation of childhood asthma.

Persistent nocturnal cough in childhood: a population based study

A cross sectional epidemiological study was carried out to investigate the validity of persistent nocturnal cough (PNC) as an independent marker of childhood asthma. A screening questionnaire on respiratory symptoms was applied to 4003 children attending primary schools in Aberdeen, after which 799 symptomatic children and a random selection of 229 asymptomatic children were invited to attend for a diagnostic interview. Six hundred and seven (359 boys and 248 girls) symptomatic children and 135 asymptomatic children (57 boys and 78 girls) were selected from the screening questionnaires. Of 607 children with respiratory symptoms when interviewed, 27 (nine boys and 18 girls) had isolated PNC, and 97 (51 boys and 46 girls) had multiple symptoms (polysymptomatic asthma). The incidence of prematurity was highest in the group with PNC (19%). The prevalence of hay fever in children with PNC (11%) was similar to that of the asymptomatic group (15%) and less than that in the group with polysymptomatic asthma (41%). Eczema was twice as common in the PNC (19%) as in the asymptomatic children (10%) but only half as common in the polysymptomatic asthma group (35%). The prevalence of a parental history of hay fever was similar in all three groups. The prevalence of a parental history of eczema was similar in the PNC (7%) and asymptomatic (7%) groups but higher in the polysymptomatic asthma group (22%). The prevalence of a history of parental asthma was 30% in children with PNC, 13% in the asymptomatic group, and 42% in those with polysymptomatic asthma. The parents of three (11%) children with PNC were aware of a diagnosis of asthma; two of these children (7%) were on inhaled bronchodilator treatment and one (4%) was on a slow release theophylline preparation. Using a stepwise discriminant analysis procedure, in 18 (67%) children with PNC predicted membership was in the asymptomatic group and only nine (33%) children with PNC were grouped into the polysymptomatic asthma category. It is concluded that the clinical features of children with PNC resembled those of the asymptomatic population more closely than those of the polysymptomatic asthmatic population. In this age group PNC, in the absence of wheeze, shortness of breath or tightness in the chest, is likely to be a manifestation of atypical or hidden asthma in only a minority of cases.