Factors associated with asthma in school children

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

Background and objective

An increasing trend of asthma prevalence was observed in Asia; however, contributions of environmental and host-related risk factors to the development of this disease remain uncertain. This study aimed to perform a systematic review and meta-analysis for asthma-associated risk factors reported in Asia.

Methods

We systematically searched three public databases (Web of Science, PubMed, and Scopus) in Feb 2021. We only included articles that reported environmental and host-related risk factors associated with asthma in the Asian population. Random-effect meta-analyses were conducted for frequently reported asthma-associated risk factors to provide an overall risk estimate of asthma development.

Results

Of 4030 records obtained from public databases, 289 articles were selected for review. The most frequently reported asthma-associated risk factor was the family history of allergy-related conditions. The random-effect asthma risk estimates (pooled odds ratio, OR) were 4.66 (95% confidence interval (CI): 3.73–5.82) for the family history of asthma, 3.50 (95% CI: 2.62–4.67) for the family history of atopy, 3.57 (95% CI: 3.03–4.22) for the family history of any allergic diseases, 1.96 (95% CI: 1.47–2.61) for the family history of allergic rhinitis, and 2.75 (95% CI: 1.12–6.76) for the family history of atopic dermatitis. For housing-related factors, including the presence of mold, mold spots, mold odor, cockroach, water damage, and incense burning, the random-effect pooled OR ranged from 1.43 to 1.73. Other risk factors with significant pooled OR for asthma development included male gender (1.30, 95% CI: 1.23–1.38), cigarette smoke exposure (1.44, 95% CI: 1.30–1.60), cigarette smoking (1.66, 95% CI: 1.44–1.90), body mass index (BMI)–related parameters (pooled OR ranged from 1.06 to 2.02), various types of air pollution (NO₂, PM10, and O₃; pooled OR ranged from 1.03 to 1.22), and pre- and perinatal factors (low birth weight, preterm birth, and cesarean section; pooled OR ranged from 1.14 to 1.32).

Conclusions

The family history of asthma was the most frequently reported risk factor for asthma development in Asia with the highest risk estimate for asthma development. This suggests a major role of the genetic component in asthma pathogenesis. Further study on asthma genetics is required to improve the current understanding of asthma etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-021-00273-x.

The association between caesarean section and childhood asthma: an updated systematic review and meta-analysis

Background

Investigating the association between caesarean section (SC) and childhood asthma has shown contradictory results in different studies. The present study was conducted to determine the association between SC and childhood asthma.

Material and method

The present study was conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. All the steps of the study were conducted independently by two reviewers from the inception until February 1, 2019. In case of disagreement, the third reviewer resolved it. We searched international online databases, including Scopus, Cochrane Library, PubMed/Medline, Embase, Web of Science (ISI), Science Direct, and Google scholar. The results of studies were combined using random effects model, and heterogeneity was measured through I² index and Cochran’s Q test. Comprehensive Meta-Analysis Software was used for meta-analysis. The significance level of all tests was considered to be P < 0.05.

Results

The heterogeneity rate was high (I² = 67.31%, P < 0.001) in 37 studies. The results showed that SC increased the risk of childhood asthma (RR (relative risk) = 1.20 [95% CI 1.15–1.25, P < 0.001]). The association between emergency and elective SC and childhood asthma was significant with RR of 1.18 (95% CI 1.07–1.29, P < 0.001) in 13 studies and 1.23 (95% CI 1.20–1.26, P < 0.001) in 13 studies, respectively. The subgroup analysis for RR of childhood asthma in SC indicated that study design (P = 0.306), prospective/retrospective studies (P = 0.470), quality of studies (P = 0.514), continent (P = 0.757), age of diagnosis (P = 0.283) and year of publication (P = 0.185) were not effective in the heterogeneity of studies. Sensitivity analysis by removing one study at a time indicated that the overall estimate is robust.

Conclusion

According to the meta-analysis, SC (overall, elective, and emergency) increased the risk of childhood asthma. Therefore, it is hoped that developing clinical guidelines and implementing appropriate management plans would diminish the risk of asthma.

Asthma and obesity in the Middle East region: An overview

This paper aims to cover the current status of asthma and obesity in the Middle East, as well as to introduce the various studies tying the two diseases; further expanding on the proposed mechanisms. Finally, the paper covers recent literature related to sphingolipids and its role in asthma, followed by recommendations and future directions. In preparation of this paper, we searched PubMed and Google Scholar, with no restrictions, using the following terms; asthma, obesity, Middle East, sphingolipids. We also used the reference list of retrieved articles to further expand on the pool of articles that were used for this review.

Association of croup with asthma in children: A cohort study

Asthma and croup are common inflammatory airway diseases involving the bronchus in children. However, no study has reported the effects of urbanization, sex, age, and bronchiolitis on the association of croup and its duration with asthma development. We used the Taiwan Longitudinal Health Insurance Database (LHID) to perform this population-based cohort study; here, the cluster effect caused by hospitalization was considered to evaluate the association between croup and asthma development and the risk factors for asthma in children of different age groups. We evaluated children with croup aged <12 years (n = 1204) and age-matched control patients (n = 140,887) by using Cox proportional hazards regression analysis within a hospitalization cluster. Of all 142,091 patients, 5799 (including 155 with croup [419 per 1000 person-y] and 5644 controls [106 per 1000 person-y]) had asthma during the 5-year follow-up period. During the 5-year follow-up period, the hazard ratios (HRs [95% CIs]) for asthma were 2.10 (1.81-2.44) in all children with croup, 2.13 (1.85-2.46) in those aged 0 to 5 years, and 2.22 (1.87-2.65) in those aged 6 to 12 years. Children with croup aged 7 to 9 years had a higher HR for asthma than did those in other age groups. Boys with croup had a higher HR for asthma. The adjusted HR for asthma was 1.78 times higher in children with croup living in urban areas than in those living in rural areas. In conclusion, our analyses indicated that sex, age, bronchiolitis, and urbanization level are significantly associated with croup and asthma development. According to our cumulative hazard rate curves, younger children with croup should be closely monitored for asthma development for at least 3 years.

Antenatal steroid therapy for fetal lung maturation and the subsequent risk of childhood asthma: a longitudinal analysis

This study was designed to test the hypothesis that fetal exposure to corticosteroids in the antenatal period is an independent risk factor for the development of asthma in early childhood with little or no effect in later childhood. A population-based cohort study of all pregnant women who resided in Nova Scotia, Canada, and gave birth to a singleton fetus between 1989 and 1998 was undertaken. After a priori specified exclusions, 80,448 infants were available for analysis. Using linked health care utilization records, incident asthma cases developed after 36 months of age were identified. Extended Cox proportional hazards models were used to estimate hazard ratios while controlling for confounders. Exposure to corticosteroids during pregnancy was associated with a risk of asthma in childhood between 3–5 years of age: adjusted hazard ratio of 1.19 (95% confidence interval: 1.03, 1.39), with no association noted after 5 years of age: adjusted hazard ratio for 5–7 years was 1.06 (95% confidence interval: 0.86, 1.30) and for 8 or greater years was 0.74 (95% confidence interval: 0.54, 1.03). Antenatal steroid therapy appears to be an independent risk factor for the development of asthma between 3 and 5 years of age.

Antenatal steroid therapy for fetal lung maturation: is there an association with childhood asthma?

PURPOSE

This study was designed to test the hypothesis that fetal exposure to corticosteroids in the antenatal period is an independent risk factor for the development of asthma in childhood.

METHODS

A population-based cohort study was conducted of all pregnant women who resided in Nova Scotia, Canada, and gave birth to a singleton fetus between January 1989 and December 1998 and lived to discharge. After exclusions, 79,395 infants were available for analysis. Using linked health care utilization records, incident asthma cases between 36 to 72 months of age were identified. Generalized Estimating Equations were used to estimate the odds ratio of the association between exposure to corticosteroids and asthma while controlling for confounders.

RESULTS

Over the 10 years of the study corticosteroid therapy increased by threefold. Exposure to corticosteroids during pregnancy was associated with a risk of asthma in childhood: adjusted odds ratio of 1.23 (95% confidence interval: 1.06, 1.44).

CONCLUSIONS

Antenatal steroid therapy appears to be an independent risk factor for the development of asthma between 36 and 72 months of age. Further research into the smallest possible steroid dose required to achieve the desired post-natal effect is needed to reduce the risk of developing childhood asthma.

Developing asthma in childhood from exposure to secondhand tobacco smoke: insights from a meta-regression

OBJECTIVE

Studies have identified associations between household secondhand tobacco smoke (SHS) exposure and induction of childhood asthma. However, the true nature and strength of this association remains confounded in many studies, producing inconsistent evidence. To look for sources of potential bias and try to uncover consistent patterns of relative risk estimates (RRs), we conducted a meta-analysis of studies published between 1970 and 2005.

DATA SOURCES

Through an extensive literature search, we identified 38 epidemiologic studies of SHS exposure and the development of childhood asthma (that also controlled for atopy history) from 300 potentially relevant articles.

DATA SYNTHESIS

We observed substantial heterogeneity within initial summary RRs of 1.48 [95% confidence interval (CI), 1.32-1.65], 1.25 (1.21-1.30), and 1.21 (1.08-1.36), for ever, current, and incident asthma, respectively. Lack of control for type of atopy history (familial or child) and child's own smoking status within studies and age category altered summary RRs in separate meta-regressions. After adjusting for these confounding characteristics, consistent patterns of association emerged between SHS exposure and childhood asthma induction. Our summary RR of 1.33 (95% CI, 1.14-1.56) from studies of incident asthma among older children (6-18 years of age) is 1.27 times the estimate from studies of younger children and higher than estimates reported in earlier meta-analyses.

CONCLUSIONS

This new finding indicates that exposure duration may be a more important factor in the induction of asthma than previously understood, and suggests that SHS could be a more fundamental and widespread cause of childhood asthma than some previous meta-analyses have indicated.

Gesundheitsbezogene Lebensqualität bei übergewichtigen Kindern

Zusammenfassung. Die Zahl übergewichtiger Kinder ist in den letzten Jahren stark angestiegen. Gut erforscht sind medizinische und psychosoziale Folgebelastungen des Übergewichts; zur Lebensqualität übergewichtiger Kinder liegen jedoch bislang nur wenige Befunde vor. Die vorliegende Studie befasst sich daher mit der Fragestellung, ob und in welchen Bereichen Unterschiede in der Lebensqualität zwischen übergewichtigen und normalgewichtigen gesunden bzw. chronisch kranken Kindern vorliegen. An der Studie nahmen insgesamt 87 Probanden: 27 übergewichtige, 30 normalgewichtige gesunde, 30 chronisch kranke (18 diabeteskranke und 12 asthmakranke) Kinder teil. Die gesundheitsbezogene Lebensqualität wurde anhand des “Fragebogens zur Erfassung der gesundheitsbezogenen Lebensqualität bei Kindern und Jugendlichen - revidierte Form“ (KINDL®, Ravens-Sieberer & Bullinger, 2000 ) erfasst. Die Ergebnisse deuten auf eine erhebliche Beeinträchtigung der Lebensqualität übergewichtiger Kinder in mehreren Bereichen hin: Die übergewichtigen Kinder schätzten sich hinsichtlich des Bereichs “körperliches Wohlbefinden“ und der gesamten Lebensqualität deutlich schlechter ein als die normalgewichtigen gesunden und die chronisch kranken Kinder. In den Bereichen “psychisches Wohlbefinden“ und “Freunde“ fanden sich Abweichungen nach unten lediglich im Vergleich zu den normalgewichtigen gesunden Kindern. Übergewichtige und chronisch kranke Kinder waren in ihrer Selbsteinschätzung bezüglich dieser Bereiche miteinander vergleichbar. Die Ergebnisse werden in den bisherigen Forschungsstand eingeordnet und kritisch diskutiert. Perspektiven für die zukünftige Adipositasforschung werden abgeleitet.

Low levels of immunoglobulin A in children with intrinsic asthma: a possible protection against atopy

Immunoglobulin A and G (IgA, IgG) serum concentrations were detected in children with nonallergic/intrinsic (36 children) or allergic/extrinsic asthma (43 children) and in age-matching control children (40 children). Asthmatic children with allergic asthma had lower IgA (1.36+/-0.54 g/L) and higher IgG (10.48+/-2.77 g/L) levels than the age-matching control children group (1.63+/-0.69 vs. 9.01+/-2.32 g/L). Children with nonallergic/intrinsic asthma had lower IgA (1.03+/-0.41 g/L) ( p = 0.004) and IgG (8.38+/-1.93 g/L) (p = 0.001) levels than the allergic/extrinsic asthma group (1.36+/-0.54 vs. 10.48+/-2.77 g/L). Low IgA levels were found in children with nonallergic/intrinsic asthma and high IgG levels were found in those children with allergic/extrinsic childhood asthma. The hypothesis is that the increased incidence of asthma in the population may be caused by a decrease in childhood infections (hygiene hypothesis). Frequent infections in early life boost the immune system, stimulating Th1-type response in young children and reducing the risk of atopic diseases. Our hypothesis is that low IgA (and/or IgG) levels in our patients might be responsible for infection development among those children with nonallergic/intrinsic asthma. These infections stimulate the normal development of immune system in young children, reducing risk of atopy, so that those children do not get allergic/extrinsic childhood asthma. Intrinsic childhood asthma=nonallergic (nonatopic) childhood asthma. Extrinsic childhood asthma=allergic (atopic) childhood asthma.

Schoolboys with bronchial asthma in Al-Khobar City, Saudi Arabia: are they at increased risk of school absenteeism?

The objective of this cross-sectional study was to determine the mean period of school absenteeism (MPSA) among asthmatic Saudi schoolboys of Al-Khobar City and to determine the factors associated with the absenteeism. The methodology included the distribution of a self-administered questionnaire, which was completed by the parents of 1482 schoolboys who satisfied the selection criteria of the study. The prevalence rate of questionnaire-diagnosed asthma (QDA) was 9.5% (141/1482). The MPSA among questionnaire-diagnosed asthmatic boys (QDAs) was 13.6 +/- 3.4 days compared to 3.7 +/- 2.2 days among non questionnaire-diagnosed asthmatic boys (non QDAs). Among QDAs, the MPSA was associated significantly and positively with those who were younger, and with decreasing levels of socioeconomic class, histories of pets at home, presence of a currently smoking family member (father or both parents), visit to a hospital emergency room, and admission to hospital. It was significantly and negatively associated with concomitant use of prophylactic medication(s), including those used appropriately. The QDAs from middle and lower socioeconomic classes showed less use of prophylactic medication(s) but more histories of visits to an emergency room and of admissions to hospital. The multiple linear regression equation for the total period of school absenteeism (TPSA) during the 1995 academic year was generated. Asthmatic school children have a higher MPSA compared to their non asthmatic classmates. The risk of suffering the impacts of this disease is shown to be particularly increased among QDAs belonging to less socioeconomically advantaged families.

Socioeconomic differences in children's health: how and why do these relationships change with age?

The effects of socioeconomic status (SES) on health are well documented in adulthood, but far less is known about its effects in childhood. The authors reviewed the literature and found support for a childhood SES effect, whereby each decrease in SES was associated with an increased health risk. The authors explored how this relationship changed as children underwent normal developmental changes and proposed 3 models to describe the temporal patterns. The authors found that a model's capacity to explain SES-health relationships varied across health outcomes. Childhood injury showed stronger relationships with SES at younger ages, whereas smoking showed stronger relationships with SES in adolescence. Finally, the authors proposed a developmental approach to exploring mechanisms that link SES and child health.

Familial risk of asthma among adolescents and their relatives in Taiwan

Although family studies have established that asthma has a hereditary basis, little evidence has been presented about the family risk of simple asthma (AS or nonatopic asthma) and asthma with other atopic diseases (AWAD or atopic asthma) after adjusting for potential risk factors. In this study, data were collected on demographic variables and a wide range of known risk factors for asthma. Study participants were asthmatic adolescents and controls, and their relatives. The role of a familial history of asthma and atopic diseases in predicting asthma risk among asthmatic adolescents and their relatives was evaluated in a population-based family study conducted in southern Taiwan. Asthma risk factor data were collected through telephone interviews with students' parents for 207 asthmatic adolescents 11-16 years of age, their 1600 relatives, and 207 nonasthmatic adolescents in the control group and their 1638 relatives. The results show (after adjusting potential confounders) that a family history of asthma is highly associated with asthma in adolescents. Having two or more family members with asthma was associated with a 3.4-fold (95% confidence interval [CI] = 1.0-12.0) increased risk of asthma among adolescents. Logistic regression was used to assess the effects of having an asthmatic relative and the effect of atopic diseases among relatives of cases. Having a family history of asthma and other atopic conditions, such as rhinitis and atopic dermatitis (adjusted odds ratio [AOR] = 3.64, 95% CI = 2.29-5.74 and AOR = 1.94, 95% CI = 1.53-2.46, respectively), was found to be a significant predictor of asthma in children. Along with a history of allergic rhinitis or atopic dermatitis, familial risks of asthma occurring in adolescents with and without other atopic diseases will be analyzed separately. A critical finding was the significant difference in a risk of asthma and atopic diseases among the relatives of asthma cases with atopic diseases and controls. However, for relatives of asthma cases without atopic diseases compared to control probands, AORs were highly significant for family history of asthma, but not for the family history of atopic diseases. These findings suggest that both forms of asthma may be hereditary, but there are differences in their modes of inheritance. Atopic status itself did not predispose a child to AS. A concomitant inheritance of a predisposition to asthma and atopic condition for AWAD cases was suggested.

Health effects of passive smoking. 6. Parental smoking and childhood asthma: longitudinal and case-control studies

BACKGROUND

The relation of parental smoking to wheezing and asthma occurring after the first year of life was assessed by a systematic quantitative review of case-control and longitudinal studies, complementing earlier reviews of cross sectional surveys and wheezing in early childhood.

METHODS

Fifty one relevant publications were identified after consideration of 1593 abstracts selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified six studies of asthma incidence, seven of prognosis, 22 case-control studies, and 10 case series addressing disease severity.

RESULTS

Maternal smoking was associated with an increased incidence of wheezing illness up to age 6 (pooled odds ratio 1.31, 95% CI 1.22 to 1.41), but less strongly thereafter (1.13, 95% CI 1.04 to 1.22). The long term prognosis of early wheezing illness was better if the mother smoked. The pooled odds ratio for asthma prevalence from 14 case-control studies was 1.37 (95% CI 1.15 to 1.64) if either parent smoked. Four studies suggest that parental smoking is more strongly associated with wheezing among non-atopic children. Indicators of disease severity including symptom scores, attack frequency, medication use, hospital attendance, and life threatening bronchospasm were in general positively related to household smoke exposure.

CONCLUSIONS

The excess incidence of wheezing in smoking households appears to be largely non-atopic "wheezy bronchitis" with a relatively benign prognosis, but among children with established asthma, parental smoking is associated with more severe disease. This apparent paradox may be reconciled if environmental tobacco smoke is considered a co-factor provoking wheezing attacks, rather than a cause of the underlying asthmatic tendency.