Early life circumstances and atopic disorders in childhood

BCG Vaccination in Early Childhood and Risk of Atopic Disease: A Systematic Review and Meta-Analysis

Background

Several large-scale studies suggest that Bacille Calmette–Guerin (BCG) vaccination in early childhood may reduce the risk of atopic diseases, but the findings remain controversial. Here, we aimed to investigate the potential correlation between early childhood BCG vaccination and the risk of developing atopic diseases.

Methods

Eligible studies published on PubMed, EMBASE, and Cochrane CENTRAL were systematically sourced from 1950 to July 2021. Studies with over 100 participants and focusing on the association between BCG vaccine and atopic diseases including eczema, asthma, and rhinitis were included. Preliminary assessment of methods, interventions, outcomes, and study quality was performed by two independent investigators. Odds ratio (OR) with 95% confidence interval (CI) was calculated. Random effects of the meta-analysis were performed to define pooled estimates of the effects.

Results

Twenty studies with a total of 222,928 participants were selected. The quantitative analysis revealed that administering BCG vaccine in early childhood reduced the risk of developing asthma significantly (OR 0.77, 95% CI 0.63 to 0.93), indicating a protective efficacy of 23% against asthma development among vaccinated children. However, early administration of BCG vaccine did not significantly reduce the risk of developing eczema (OR 0.94, 95% CI 0.76 to 1.16) and rhinitis (OR 0.99, 95% CI 0.81 to 1.21). Further analysis revealed that the effect of BCG vaccination on asthma prevalence was significant especially in developed countries (OR 0.73, 95% CI 0.58 to 0.92).

Conclusion

BCG vaccination in early childhood is associated with reduced risk of atopic disease, especially in developed countries.

Gastroenteritis during infancy is a novel risk factor for allergic disease

Antibiotics during infancy, delivery, and breastfeeding affect the intestinal microbiota in early life and is associated with allergic disease. Gastroenteritis (GE) during infancy also affects intestinal microbiota in early life, however, its relationship to allergic disease has not been investigated.Data of 45,499 males and 49,430 females, from birth to 5 years of age, were collected from a national database in Taiwan. Subjects were categorized into early GE (GE within 0-6 months) and non-early GE group (no GE within 0-6 months). The rates of asthma (AS), allergic rhinitis (AR), and atopic dermatitis (AD) over 5 years were evaluated and compared between the groups. In patients with AS, AR, and AD, the number of clinical visits and drug prescriptions for the allergic disease was also evaluated to assess the effect of early GE on allergic disease.After adjusting for the effect of GE in later life and other factors, the rates of AS [OR (odds ratio) 1.54, 95% confidence interval (CI) 1.48-1.60], AR [OR 1.49, 95% CI 1.45-1.54], and AD [OR 1.40, 95% CI 1.33-1.47] were higher in the early GE group than in the non-early GE group. The magnitude of the increase was higher in females than in males. In those with AS, AR, and AD, the number of clinical visits and drug prescriptions was not different between the early GE and non-early GE groups. In children with early GE, good control of GE in the following years lowered the rate of allergic disease.Early-life GE was associated with increased rates of AS, AR, and AD in later life and this was trend more prominent in females.

Neonatal bilirubin levels and childhood asthma in the US Collaborative Perinatal Project, 1959-1965

Evidence shows that asthma originates in early life. Studies have found that phototherapy and/or neonatal jaundice may be associated with asthma. We investigated the association between neonatal bilirubin levels and childhood asthma without phototherapy intervention in the Collaborative Perinatal Project, a multicenter prospective cohort study conducted in the United States from 1959 to 1965. A total of 54,795 livebirths were included, and 40,063 children were followed up until 7 years of age or older. Total serum bilirubin (TSB) levels were examined at 48 hours postpartum in newborns with birthweights of 2,250 g or more. Information on asthma and other diseases through age 7 years was summarized and confirmed by a group of pediatricians and child neurologists. Among 28,807 term infants, the overall prevalence of asthma was 5.26%. Risks of asthma increased with both maximum TSB levels and TSB levels at 48 hours postpartum (P for trend < 0.01). Neonatal maximum TSB levels greater than 15 mg/dL were associated with a 61% increase in the risk of childhood asthma (odds ratio = 1.61, 95% confidence interval: 1.04, 2.08) after adjustment for confounders. In this prospective cohort study of infants born at a time when phototherapy was unavailable, neonatal hyperbilirubinemia was associated with an increased risk of childhood asthma.

The winding road to understanding the neonatal origins of inflammatory gastrointestinal disorders

Beginning with the observation that birth weight correlates with increased risk of cardiovascular disease, the concept of neonatal programming, that the environmental influence on fetal and neonatal development results in modification of the risk profile for adult disease, has begun to emerge as an important component to understanding the origin of chronic diseases of many different organ systems. Until recently, the gastrointestinal system has not been considered. Our understanding of the pathogenesis of many intestinal inflammatory disorders is still incomplete; however, a brief review of what is known reveals several opportunities for the early intraluminal environment to affect the development of the intestinal immune system. Early clinical observations such as the increased risk of celiac disease observed in those born by cesarean section and the protective effect of breast-feeding against inflammatory bowel disease and celiac disease support the role of neonatal programming in the development of chronic inflammatory gastrointestinal disease. Additional, more robust clinical studies are needed to confirm this role. Furthermore, examination of the possible mechanisms of immune phenotype modification is necessary.

Asthma and risk of non-respiratory tract infection: a population-based case-control study

OBJECTIVES

Asthmatics have increased risks of airway-related infections. Little is known about whether this is true for non-airway-related serious infections such as Escherichia coli bloodstream infection (BSI). We assessed whether asthma is associated with a risk of developing community-acquired E coli BSI.

DESIGN

The study was designed as a population-based retrospective case-control study.

SETTING

This population-based study was conducted in Olmsted County, Minnesota.

PARTICIPANTS

The study included 259 all eligible community-acquired E coli BSI cases in Olmsted County, MN between 1998 and 2007 and 259 birthday-matched, gender-matched and residency-matched controls.

PRIMARY AND SECONDARY OUTCOME MEASURES

Only community-acquired E coli BSI cases as the primary outcome was included. Asthma status as an exposure was ascertained by predetermined criteria. An adjusted OR and 95% CI for the association between asthma and risk of community-acquired E coli BSI was calculated using conditional logistic regression.

RESULTS

Of 259 eligible cases, 179 (69%) were women and mean age was 61±22 years. Of the 259 cases 37 (14%) and 16 (6%) of 259 controls had a prior history of asthma (adjusted OR 2.74; 95% CI 1.11 to 6.76; p=0.029). The population attributable risk of asthma for community-acquired E coli BSI was 9%. Although not statistically significant, there was a borderline association between having a history of food allergy and increased risk of community-acquired E coli BSI (6% vs 2%; adjusted OR 3.51; 95% CI 0.94 to 13.11; p=0.062).

CONCLUSIONS

Based on the findings of the current population-based, case-control investigation, a history of asthma may be associated with risk of community-acquired E coli BSI. The impact of asthma on risk of microbial infections may go beyond airways.

Automated chart review for asthma cohort identification using natural language processing: an exploratory study

BACKGROUND

A significant proportion of children with asthma have delayed diagnosis of asthma by health care providers. Manual chart review according to established criteria is more accurate than directly using diagnosis codes, which tend to under-identify asthmatics, but chart reviews are more costly and less timely.

OBJECTIVE

To evaluate the accuracy of a computational approach to asthma ascertainment, characterizing its utility and feasibility toward large-scale deployment in electronic medical records.

METHODS

A natural language processing (NLP) system was developed for extracting predetermined criteria for asthma from unstructured text in electronic medical records and then inferring asthma status based on these criteria. Using manual chart reviews as a gold standard, asthma status (yes vs no) and identification date (first date of a "yes" asthma status) were determined by the NLP system.

RESULTS

Patients were a group of children (n = 112, 84% Caucasian, 49% girls) younger than 4 years (mean 2.0 years, standard deviation 1.03 years) who participated in previous studies. The NLP approach to asthma ascertainment showed sensitivity, specificity, positive predictive value, negative predictive value, and median delay in diagnosis of 84.6%, 96.5%, 88.0%, 95.4%, and 0 months, respectively; this compared favorably with diagnosis codes, at 30.8%, 93.2%, 57.1%, 82.2%, and 2.3 months, respectively.

CONCLUSION

Automated asthma ascertainment from electronic medical records using NLP is feasible and more accurate than traditional approaches such as diagnosis codes. Considering the difficulty of labor-intensive manual record review, NLP approaches for asthma ascertainment should be considered for improving clinical care and research, especially in large-scale efforts.

Perinatal factors and respiratory health in children

BACKGROUND

There is conflicting evidence regarding the associations between anthropometric birth measures and asthma and lung function in children, particularly for apparently healthy infants born at term.

OBJECTIVE

Our objective was to elucidate these relationships paying particular attention to features of study design and analysis that may threaten the validity of previous studies in this field.

METHODS

We analysed data from a cohort of children with a family history of asthma who were recruited antenatally. Anthropometric birth measures and potential confounders were recorded at birth and within the first year of life. Lung function and asthma outcomes were measured at 8 years of age. Airway hyperresponsiveness (AHR) was measured by methacholine challenge. The potential for a reversal paradox, due to inclusion of covariates on the causal pathway, was investigated.

RESULTS

Four hundred and fifty (73% of the initial cohort) children were tested at age 8 years. Birth weight in the lowest tertile was associated with current asthma (OR 1.95, 95% CI 1.08, 3.54) and recent wheeze (OR 1.87, 95%CI 1.08, 3.24), but not with AHR (OR 1.37, 95% CI 0.68, 2.78). Birth weight was positively associated with lung function. Current height modified the relationship between birth length and lung function suggesting that post-natal growth has an effect on this relationship.

CONCLUSIONS

Low birth weight is associated with a greater risk of current asthma and lower lung function at 8 years in children with a family history of asthma. Current height should be treated as an effect modifier when investigating the fetal origins hypothesis.

Population-based study on association between birth weight and risk of asthma: a propensity score approach

BACKGROUND

Previous studies that assessed the role of birth weight in the risk of asthma have been limited because of selection bias and covariate imbalance.

OBJECTIVE

To assess the association between birth weight and risk of asthma by applying a propensity score approach.

METHODS

The study was designed as a retrospective cohort study based on a birth cohort of children born between January 1, 1976, and December 31, 1979, in Rochester, Minnesota. The propensity scores for birth weight were formulated using 16 covariates. We matched the propensity scores for children having low birth weight (<2,500 g) within a caliper of 0.2 SD of logit function of propensity scores. We calculated the cumulative incidence of asthma between low and normal birth weight groups using the Kaplan-Meier curve.

RESULTS

There were 3933 eligible children born between January 1, 1976, and December 31, 1979. Before matching, 13 of the 193 children (6.7%) born weighing 2,500 g developed asthma, whereas 201 of the 3,740 children (5.4%) born weighing 2,500 g and above developed asthma (P=.42). There were significant covariate imbalances between comparison groups. However, after propensity score matching, covariate imbalance was significantly reduced, and children born weighing less than 2,500 g had a similar risk to matched children born with normal birth weight (8.3% vs 7.3%, P=.75).

CONCLUSION

Birth weight is not associated with risk of asthma during the first 6 years of life. The propensity score may be a useful method for observational studies concerning asthma epidemiology.

The burden of allergic rhinitis and asthma

Asthma and allergic rhinitis are common health problems that cause major illness and disability worldwide. The prevalence of allergic rhinitis is estimated to range from 10% to 20% in the USA and Europe. Multiple factors contribute to the wide range of reported prevalence rates. These include type of prevalence rate reported (current or cumulative), study selection criteria, age of participants, differences in survey methods, varied geographic locations and socioeconomic status, any of which are significant enough to confound direct comparison between studies. There is no standard set of diagnostic criteria for allergic rhinitis. In most studies, the criteria for diagnosis are based on the subject's reporting, solely by questionnaire and rarely confirmed by skin testing. In addition, most studies focus on hay fever, leaving perennial allergic rhinitis underestimated. Sinus imaging is generally not performed and, therefore, rhinosinusitis not differentiated. Some investigators report 'current' prevalence while others report 'cumulative' or 'lifetime' prevalence. Epidemiologic studies have consistently shown that asthma and rhinitis often coexist in the same patients. The prevalence of asthma is <2% in subjects without rhinitis while it varies from 10% to 40% in patients with rhinitis. Furthermore, the majority of patients with asthma experience rhinitis, which is a factor in the risk for asthma. Despite recognition that allergic rhinitis and asthma are global health problems, there are insufficient epidemiologic data and more data are needed with regard to their etiologic risk factors and natural history. This aim of this review is to enable the reader to discuss prevalence, risk factors and prognosis of allergic rhinitis and asthma.

Vaccination status and health in children and adolescents: findings of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)

BACKGROUND

Whether unvaccinated children and adolescents differ from those vaccinated in terms of health is subject to some discussion.

METHOD

We evaluated data on diseases that are preventable by vaccination, infectious and atopic diseases, and vaccinations received that had been collected between 2003 and 2006 in a representative sample of 17 641 subjects aged 0 to 17 years in the framework of the German Health Interview and Examination Survey for Children and Adolescents (Kinder- und Jugendgesundheitssurvey, KiGGS).

RESULTS

Evaluable data on vaccinations were available for 13 453 subjects aged 1-17 years from non-immigrant families. 0.7% of them (95% confidence interval: 0.5%-0.9%) were not vaccinated. The lifetime prevalence of diseases preventable by vaccination was markedly higher in unvaccinated than in vaccinated subjects. Unvaccinated children aged 1-5 years had a median number of 3.3 (2.1-4.6) infectious diseases in the past year, compared to 4.2 (4.1-4.4) in vaccinated children. Among 11- to 17-year-olds, the corresponding figures were 1.9 (1.0-2.8) (unvaccinated) versus 2.2 (2.1-2.3) (vaccinated). The lifetime prevalence of at least one atopic disease among 1- to 5-year-olds was 12.6% (5.0%-28.3%) in unvaccinated children and 15.0% (13.6%-16.4%) in vaccinated children. In older children, atopy was more common, but its prevalence was not found to depend on vaccination status: among 6- to 10-year-olds, the prevalence figures were 30.1% (12.9%-55.8%) for unvaccinated children versus 24.4% (22.8%-26.0%) for vaccinated children, and the corresponding figures for 11- to 17-year-olds were 20.3% (10.1%-36.6%) versus 29.9% (28.4%-31.5%).

CONCLUSION

The prevalence of allergic diseases and non-specific infections in children and adolescents was not found to depend on vaccination status.

Maternal and perinatal characteristics and the risk of cow's milk allergy in infants up to 2 years of age: a case-control study nested in the Finnish population

This study examined whether maternal background and perinatal factors were associated with the risk of cow's milk allergy (CMA) in infants up to 2 years of age in a nested case-control study. All children born in 1996-2004 in Finland and diagnosed with CMA by 2006 were identified (n = 16,237). For each case, one matched control was selected. Information on maternal and perinatal factors was derived from the Medical Birth Register. The associations were analyzed by conditional logistic regression. Cesarean section (adjusted odds ratio (OR) = 1.18, 95% confidence interval (CI): 1.10, 1.27) and high maternal age (> or =35 years; adjusted OR = 1.23, 95% CI: 1.11, 1.36) were associated with increased risk, whereas low maternal socioeconomic status (adjusted OR = 0.65, 95% CI: 0.59, 0.71), smoking (adjusted OR = 0.72, 95% CI: 0.67, 0.79), high number of previous deliveries (> or =5; adjusted OR = 0.71, 95% CI: 0.59, 0.86), and multiple pregnancy (adjusted OR = 0.70, 95% CI: 0.60, 0.82) were associated with decreased risk of CMA. In conclusion, maternal background and perinatal factors may play a role in the development of CMA, but further research is needed to clarify these associations and the underpinning biologic mechanisms.

Prenatal and perinatal factors and risk of multiple sclerosis

BACKGROUND

A potential role of prenatal and perinatal exposures in autoimmunity has been hypothesized, but few studies have examined the relation between various prenatal and perinatal factors and the risk of multiple sclerosis (MS).

METHODS

The study population included participants in the Nurses' Health Studies--2 prospective cohorts that together comprise 238,381 female nurses, who self-reported exposure to prenatal and perinatal factors. In addition, 35,815 nurses' mothers participated by providing detailed information regarding experiences surrounding their daughter's birth. The following prenatal and perinatal factors were studied in relation to MS: fetal growth, birth season, preterm birth, mode of delivery, maternal weight gain, medical conditions, medication use, diethylstilbestrol exposure, prenatal health care, maternal activity level, maternal obstetric history, parental age, and prenatal and childhood passive smoke exposure.

RESULTS

The sample included 723 confirmed MS cases, including 383 with diagnosis after reporting prenatal and perinatal factors. Few associations were observed. These included an increased risk among women whose mothers reported late initiation of prenatal care (after the first trimester) (27 cases; rate ratio = 1.6 [95% confidence interval = 1.0-2.4]), diabetes during pregnancy (2 cases; 10 [2.5-42]), and maternal prepregnancy overweight/obesity (20 cases; 1.7 [1.0-2.7]). Results also suggested a possible increase in incident MS risk among women with prenatal diethylstilbestrol exposure (9 cases; 1.8 [0.93-3.5]).

CONCLUSIONS

This study provides modest support for a role of prenatal factors in MS risk. The results should be interpreted cautiously due to the limited statistical power, potential for exposure misclassification, and possibility of chance findings.

Perinatal factors and the risk of asthma in childhood--a population-based register study in Finland

The aim of the study was to assess whether perinatal factors are associated with the risk of asthma in childhood in a register-based, nested case-control study in Finland. All children born between January 1, 1996, and April 30, 2004, who were entitled to a special reimbursement for antiasthmatic drugs (i.e., had diagnosed asthma by 2006 and had purchased inhaled corticosteroids or montelukast at least once), were identified (n = 21,038). For each case, one matched control child was selected. The associations between perinatal factors, derived from the Finnish Medical Birth Register, and the risk of asthma were analyzed by conditional logistic regression. In the final multivariate model, maternal asthma, young age, smoking, previous miscarriages, and a high number of previous deliveries, as well as cesarean section, low gestational age, and low ponderal index, were associated with an increased risk of asthma in children diagnosed before the age of 3 years. Among children diagnosed at the age of 3 years or later, maternal asthma, low gestational age, and low ponderal index were associated with an increased risk, and a high number of previous deliveries was associated with a decreased risk of asthma. In conclusion, perinatal factors play a role in the development of asthma in childhood, but the etiology may differ in early and late-onset asthma.

Respiratory symptoms in the first 7 years of life and birth weight at term: the PIAMA Birth Cohort

RATIONALE

The relation between birth weight and respiratory symptoms and asthma in children remains unclear. Previous studies focused on a relation at separate ages. A longitudinal analysis may lead to a better understanding.

OBJECTIVES

To estimate the effect of birth weight on the development and course of respiratory symptoms and asthma in the first 7 years of life.

METHODS

In a prospective birth cohort study, 3,628 children with a gestational age 37 weeks or more were monitored for 7 years. Parental questionnaires were used to assess respiratory health yearly. Associations of birth weight with respiratory symptoms (wheezing, coughing, respiratory infections) and doctor's diagnosis of asthma were assessed in a repeated-event analysis.

MEASUREMENTS AND MAIN RESULTS

Lower birth weight was associated with more respiratory symptoms (odds ratio [OR] per kg decrease in birth weight, 1.21; 95% confidence interval [CI], 1.09-1.34). The effect of birth weight increased from age 1 to 5, but decreased thereafter and was no longer significant at the age of 7. The effect of birth weight on respiratory symptoms was significantly greater among children exposed to tobacco smoke in their home than among nonexposed children (OR at 5 yr: 1.21 [95% CI, 1.02-1.44] and 1.52 [95% CI, 1.23-1.87], respectively). Birth weight and a doctor's diagnosis of asthma were not related (OR, 1.06; 95% CI, 0.82-1.37).

CONCLUSIONS

A lower birth weight in children born at term is associated with a transiently increased risk of respiratory symptoms. This effect is enhanced by environmental tobacco smoke exposure.