Age-period-cohort analysis of asthma prevalence among school children

Prevalence of age-dependent diseases such as asthma is confounded not only by aging effects but also by cohort and period effects. Age-period-cohort (APC) analysis is commonly performed to isolate the effects of these three factors from two-way tables of prevalence by age and birth cohort. However, APC analysis suffers from technical difficulties such as non-identifiability problems. We isolated the effects of these three factors in a step-by-step manner by analyzing Japan’s school health data collected from 1984 to 2004 focusing on asthma prevalence among school children aged 6–17 years consisting of 30 birth cohorts (entering classes). We verified the accuracy of our method showing high agreement of the observed age-, period- and cohort-specific data and the data predicted by our method. The aging effects were found to follow cubic equations whose multinomial coefficients were determined by an optimization technique. The obtained aging effect curves of age-specific asthma prevalence showed that boys reach the peak prevalence at 13 and girls at 14, declining markedly afterward. The cohort effects, defined as the arithmetic asthma prevalence means for ages 6–17 years, showed consistent upward trends for the 30 birth cohorts born in 1968–97 for both sexes. The period effects showed a consistent decline since 1984 but abruptly increased in 1999 and then declined again. We were not able to identify the exact cause of the increase in 1999, therefore, this should be examined in the future studies. Because the cohort effects show no sign of leveling off yet, asthma prevalence will likely increase in the foreseeable future.     

The association between contextual socioeconomic factors and prevalent asthma in a cohort of Southern California school children

Spatial variation in childhood asthma and a recent increase in prevalence indicate that environmental factors play a significant role in the etiology of this important disease. Socioeconomic position (SEP) has been associated inversely and positively with childhood asthma. These contradictory results indicate a need for systematic research about SEP and asthma. Pathways have been suggested for effects of SEP on asthma at both the individual and community level. We examined the relationship of prevalent asthma to community-level indicators of SEP among 5762 children in 12 Southern California communities, using a multilevel random effects model. Estimates of community-level SEP were derived by summarizing census block group-level data using a novel method of weighting by the proportion of the block groups included in a community-specific bounding rectangle that contained 95% of local study subjects. Community characteristics included measures of male unemployment, household income, low education (i.e., no high school diploma) and poverty. There was a consistent inverse association between male unemployment and asthma across the inter-quartile range of community unemployment rates, indicating that asthma rates increase as community SEP increases. The results were robust to individual-level confounding, methods for summarizing census block group data to the community level, scale of analysis (i.e., community-level vs. neighborhood-level) and the modeling algorithm. The positive association between SEP and prevalent childhood asthma might be explained by differential access to medical care that remains unmeasured, by the hygiene hypothesis (e.g., lower SES may associate with higher protective exposures to endotoxin in early life), or by SEP acting as a proxy for unmeasured neighborhood characteristics.     

The association between childhood asthma and community violence, Los Angeles County, 2000

OBJECTIVE: This study's objective is to determine if there is an association between rates of violence and rates of childhood asthma in Los Angeles County communities. METHODS: Rates of hospitalization for assault and for asthma were calculated for each ZIP Code and city in Los Angeles County. Linear regression was used to determine the effect of assault rates on asthma rates while controlling for potential confounders such as poverty and racial/ethnic distribution. At the city level, crime rates were included in the model as additional measures of community violence. RESULTS: Hospitalization rates for childhood asthma and assaults were significantly correlated at both the city (r = 0.80) and the ZIP Code (r = 0.54) levels. The association remained significant when controlling for poverty and racial/ethnic distribution with linear regression (p < 0.0001). At the city level, the variables measuring the crime rate were not significant predictors of asthma hospitalizations. CONCLUSIONS: Community violence as measured by the rate of assault hospi; talizations is associated with childhood asthma in Los Angeles County. Health care providers should consider their asthmatic patients' social environments when devising treatment plans.     

Influence of school community and fitness on prevalence of overweight in Australian school children

The study objectives were (1) to determine the variation in prevalence of overweight between school communities, (2) to evaluate the relationship between cardiorespiratory fitness and the probability of being overweight among different school communities, and (3) to test whether this relationship varies between school communities. Using a repeated cross-sectional design, data from 31,424 (15,298 girls, 16,126 boys) Australian school children who had objective assessments of body composition and physical performance were used. Ninety-one schools located across 5 states and territories were included. Independent samples were taken across 12 school years (2000–2011). Analysis used generalised linear mixed models in R with a two-level hierarchical structure—children, nested within school communities. Predictor variables considered were: level 1—gender, age, cardiorespiratory fitness and year of measurement; level 2—school community. A total of 24.6% of the children were overweight and 69% were of low fitness. Variation in the prevalence of overweight between school communities was significant, ranging from 19% to 34%. The probability of being overweight was negatively associated with increasing cardiorespiratory fitness. The relationship was steepest at low fitness and varied markedly between school communities. Children of low fitness had probabilities of being overweight ranging between 26% and 75% depending on school community, whereas those of high fitness had probabilities of < 2%. Our findings suggest that most might be gained from a public health perspective by focusing intervention on the least fit children in the worst-performing communities.     

Tobacco outlet density,neighbourhood stressors and smoking prevalence in Toronto,Canada

A growing body of research has shown that neighbourhood-level factors, such as the density of retail outlets selling tobacco and neighbourhood socioeconomic disadvantage affect smoking prevalence, with high levels of outlet density and neighbourhood disadvantage related to higher smoking prevalence.However, few studies have considered the role of other neighbourhood processes like stressors including perceived neighbourhood disorder in these effects. The present study examined the effects of tobacco outlet density, neighbourhood income and perceived neighbourhood disorder on smoking prevalence among a representative sample of 2,412 adult neighbourhood residents in a large urban centre in Canada. Tobacco outlet density and perceived neighbourhood disorder were significantly associated with smoking in an unadjusted multilevel model, but only perceived neighbourhood disorder remained significant in a model adjusting for other confounders. Findings suggest the need for community-based interventions to address the relationship between neighbourhood disorder and smoking, as well as more research on the combined role of tobacco availability and neighbourhood stressors, beyond neighbourhood socioeconomic disadvantage, on smoking behaviour.     

The prevalence of asthma in children of elementary school age in Western New York

To determine the prevalence of caregiver-reported asthma in children 4 to 13 years old in metropolitan western New York State, surveys were conducted during 1997–1999 in the Buffalo, Niagara Falls, Iroquois, and Gowanda school systems. Questionaires (3,889) were sent to the homes of elementary school children in nine schools in western New York. The caregivers were asked to complete a 13-item questionnaire for the child. Of the questionnaires, 60.5% (2,353/3,889) were completed. Of all children, 18% had physician-diagnosed asthma. Of children diagnosed with asthma, 86% were taking medication. Symptoms were consistent with suspected undiagnosed asthma for 13% of the children. Buffalo had the highest rate of diagnosed asthma (20%) for the age group. Gowanda had a prevalence of 18%, Iroquois 16%, and Niagara Falls 15%. Variations were observed in asthma prevalence rates among different racial/ ethnic groups. In general, boys had a significantly (P=.001) increased odds of being asthmatic compared with girls. Overall, African-Americans and Hispanic/Latino children had significantly (P=.012 andP=.005, respectively) higher asthma prevalence rates, two to five times those of their Caucasian peers. In Gowanda, the prevalence of diagnosed asthma among Native American children was 23%, compared to 15% among Caucasian children. Of diagnosed Native American children, 71% were female. In Gowanda, a significant association (P=.007) of asthma among children in split-grade classes was observed compared to nonsplit grades. Of Native American children in split grades, 60% were diagnosed asthmatics. These observations reveal a high prevalence of asthma in the age group of 4 to 13 year olds in western New York. Local variations in potential triggers of asthma need to be considered when advising asthmatics. The results suggest that some grades have a disproportionate amount of children with asthma. The implications of asthma for children's early education need to be examined further. This project was supported in part by a grant from Kaleida Health Foundations.     

Magnesium deficiency and its lack of association with asthma in Taiwanese elementary school children

The purpose of this study was to investigate magnesium nutritional status and its association with asthma in elementary school children (1277 boys and 1109 girls) participating in the Nutrition and Health Survey in Taiwan (NAHSIT children 2001-2002). Dietary magnesium intake was based on 24-hour dietary recalls. Serum magnesium was measured. Average magnesium intake was 247 mg and 228 mg for the boys and girls, respectively, which is equivalent to 135-123% of the relevant Taiwanese Dietary Reference Intakes (DRIs). Mean serum magnesium concentration was 0.87 mmol/L and 0.86 mmol/L, respectively. The prevalence of serum magnesium <0.8 mmol/L was 10.5-13.5% in both gender in our sample of elementary school children. In Taiwan, asthma was diagnosed in about 5.8% and 4.7% of boys and girls, respectively. In this study, there were no associations between asthma prevalence, dietary magnesium and serum magnesium concentration. In about 40% of our sample of school children, however, dietary magnesium may be suboptimal. This deficit should be targeted though improved intake of magnesium-rich foods such as whole grains, green vegetables and soybean products, particularly in Taiwanese school children whose dietary intakes are below the DRIs and/or who have low serum magnesium levels.     

儿童哮喘与肥胖相关关系的病例对照研究

目的 探讨重庆市儿童哮喘与肥胖发病风险的关联程度,为临床诊治提供参考依据。方法 采用病例对照研究,共纳入6～13岁的120名哮喘儿童及240名非哮喘儿童作为研究对象,对研究对象进行体格检查及问卷调查、血液学检测。结果 与正常对照组相比,体质指数(body mass index,BMI)的升高可增加儿童哮喘发病风险(t=8.64,P=0.000);二手烟暴露史与哮喘发病风险呈正相关(χ²=7.38,P=0.007)。哮喘组肥胖人群的胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白、C反应蛋白水平均高于正常体重组(P值均<0.05)。结论 儿童BMI及血脂谱、C反应蛋白水平的升高均可增加哮喘的发病风险。     

The association between childhood asthma prevalence and monitored air pollutants in metropolitan areas, United States, 2001-2004

Background

Air pollution exposure has been linked to adverse respiratory health outcomes among children, primarily in studies of acute exposures that are often in limited geographic areas. We sought to assess the association between chronic outdoor air pollution exposure, as measured by 12-month averages by county, and asthma among children in metropolitan areas across the nation.

Methods

Eligible children included those aged 3-17 years residing in US metropolitan areas who were sampled in the 2001-2004 National Health Interview Survey (N=34,073). 12-month average air pollutant levels for sulfur dioxide, nitrogen dioxide, ozone and particulate matter were compiled by county for 2000-2004. Eligible children were linked to pollutant levels for the previous 12 months for their county of residence. Adjusted odds ratios of having current asthma or an asthma attack in the past 12 months were estimated in single pollutant logistic regression models.

Results

Children in counties with ozone and, to a less consistent degree, particulate matter levels in the highest quartile were more likely to have current asthma and/or a recent asthma attack than children residing in counties with the lowest pollution levels; the adjusted odds for current asthma for the highest quartile of estimated ozone exposure was 1.56 (95% confidence interval [CI]: 1.15, 2.10) and for recent asthma attack 1.38 (95% CI: 0.99, 1.91). No associations were found with sulfur dioxide or nitrogen dioxide levels.

Conclusion

Although the current US standard for ozone is based on short-term exposure, this cross-sectional study suggests that chronic (12-month) exposure to ozone and particles is related to asthma outcomes among children in metropolitan areas throughout the US.     

Associations between chronic community noise exposure and blood pressure at rest and during acute noise and non-noise stressors among urban school children in India

The present study builds on prior research that has examined the association between children's chronic exposure to community noise and resting blood pressure and blood pressure dysregulation during exposure to acute stressors. A novel contribution of the study is that it examines how chronic noise exposure relates to blood pressure responses during exposure to both noise and non-noise acute stressors. The acute noise stressor was recorded street noise and the non-noise stressor was mental arithmetic. The sample consisted of 189 3rd and 6th grade children (51.9% percent boys; 52.9% 3rd graders) from a noisy (n = 95) or relatively quiet (n = 94) public school in the city of Pune, India. There were no statistically significant differences between chronic noise levels and resting blood pressure levels. However, relative to quiet-school children, noisy-school children had significantly lower increases in blood pressure when exposed to either an acute noise or non-noise stressor. This finding suggests that chronic noise exposure may result in hypo-reactivity to a variety of stressors and not just habituation to noise stressors.     

Differences in asthma prevalence between samples of American Indian and Alaska Native children

OBJECTIVES: To better understand the prevalence of asthma among American Indian and Alaska Native (AI/AN) children and to explore the contribution of locale to asthma symptoms and diagnostic assignment, the authors surveyed AI/AN middle school students, comparing responses from metropolitan Tacoma, Washington (metro WA) and a non-metropolitan area of Alaska (non-metro AK). METHODS: Students in grades 6-9 completed an asthma screening survey. The authors compared self-reported rates of asthma symptoms, asthma diagnoses, and health care utilization for 147 children ages 11-16 self-reporting as AI/AN in metro WA and 365 in non-metro AK. RESULTS: The prevalences of self-reported asthma symptoms were similar for the metro WA and non-metro AK populations, but a significantly higher percentage of metro WA than of non-metro AK respondents reported having received a physician diagnosis of asthma (OR 2.33; 95% CI 1.23, 4.39). The percentages of respondents who reported having visited a medical provider for asthma-like symptoms in the previous year did not differ. CONCLUSIONS: The difference in rates of asthma diagnosis despite similar rates of asthma symptoms and respiratory-related medical visits may reflect differences in respiratory disease patterns, diagnostic labeling practices, or environmental factors. Future attempts to describe asthma prevalence should consider the potential contribution of non-biologic factors such as diagnostic practices.     

The prevalence of smokeless tobacco use in native children in northern Saskatchewan, Canada

We used a self-administered questionnaire to develop a profile of smokeless tobacco use among 1,170 Canadian native children aged 7 to 21 years attending schools situated in remote communities in northern Saskatchewan. Nearly 30% of the sample were current users of smokeless tobacco; more than 50% of users began to use these products before the age of 12 years. More males than females chewed tobacco or dipped snuff. The results revealed a relatively high prevalence of smokeless tobacco users among the present sample of native children and were found to be consistent with data from other studies of similarly aged native populations. The results also showed a prevailing pattern of addiction among the users of smokeless tobacco. It is suggested that educational programs aimed at preventing or reducing the use of tobacco products among native populations be intensified and as well, these programs would benefit from the active participation of trained native personnel.     

The relationship between school absence, academic performance, and asthma status

BACKGROUND: Children with asthma experience more absenteeism from school compared with their nonasthma peers. Excessive absenteeism is related to lower student grades, psychological, social, and educational adjustment. Less is known about the relationship between the presence of asthma and the academic achievement in school-aged children. Since students with asthma miss more days from school, this may negatively impact their academic achievement. The goal of this study was to investigate the relationships between absenteeism, presence of asthma, and asthma severity level with standardized test level performance in a predominantly African American urban school district. METHODS: A cross-sectional analysis was conducted of 3812 students (aged 8-17 years) who took the Missouri Assessment Program (MAP) standardized test during the 2002-2003 academic year. RESULTS: After adjustment for covariates, a significant inverse relationship was found between absenteeism and test level performance on the MAP standardized test in all children (F = 203.9, p < .001). There was no overall difference in test level achievement between those with and without asthma (p = .12). Though not statistically different, those with persistent asthma showed a modestly increased likelihood of scoring below Nearing Proficient compared with those with mild intermittent asthma (adjusted odds ratio = 1.93, 95% confidence intervals = 0.93-4.01, p = .08). CONCLUSIONS: A negative impact of absenteeism on standardized test level achievement was demonstrated in children from an urban African American school district. Children with asthma perform the same academically as their nonasthma peers. However, those with persistent asthma show a trend of performing worse on MAP standardized test scores and have more absence days compared with other students. More research is warranted on the effects of persistent asthma on academic achievement.     

Prevalence of exercise-induced asthma in school children

BACKGROUND: Although asthma is the most common pulmonary condition in pediatrics, the incidence of exercise-induced asthma (EIA) in school children is not well documented and few studies have been devoted to the condition. There are considerable variations in morbidity and mortality between countries. This study was designed to evaluate the prevalence of EIA in children in the 6th grade (11-14 year-olds) in one French department (Haute-Vienne) and to identify undiagnosed cases. METHODS: The representative sample was obtained over a period of 28 days (February 2(nd) to April 10(th) 1998) by cluster sampling method, stratified by size of the schools. The number of subjects planned was 891. The selected children filled in a questionnaire on their asthma history and were subjected to an outdoor exercise test (6 minute run). Respiratory function was measured with a peak flow-meter. RESULTS: Seven hundred and eighty two school children were included in this survey. Participation rate was 87.8%. The prevalence of asthma from the questionnaire was 10.7% (CI 95%: 8.7 - 12.8). After exercise, 68 school children presented exercise-induced bronchospasm: the prevalence of the EIA was 8.7% (CI 95%: 6.9 - 10.5). Among these 68 school children, 27 were known asthmatics and 41 were not. With the 10 treated asthmatics, the overall prevalence of EIA was therefore estimated at 9.9% (CI 95%: 8.2 - 11.7). CONCLUSION: The prevalence of asthma and EIA was close to that found in other studies using a similar methodology. EIA remains under-diagnosed since 41 undeclared asthmatic school children were identified in our population. Nurses'information is necessary to initiate the use of systematically testing respiratory function (with a peak flow meter) at least once a year. Efficient management of the asthmatic child requires cooperation between the various professionals dealing with school children.     

The relationship of prenatal care and pregnancy complications to birthweight in Winnipeg, Canada.

OBJECTIVES. Prenatal care is commonly understood to have a beneficial impact on birthweight. This study describes socioeconomic differences in utilization of prenatal medical care and birthweight in a population with universal health insurance. METHODS. Measures of prenatal care utilization, incidence of pregnancy complications, and birthweight were obtained from physician reimbursement claims and hospital separation abstracts for 12,646 pregnant women. Maternal socioeconomic status was derived from small-area census data. RESULTS. Infants born to women in the poorest income quintile had lower birthweights than infants born to wealthier women. Much of the difference was associated with a higher prevalence of complications, smoking, unmarried status, and inadequate prenatal care among low-income women. The difference in birthweight between adequate and less than adequate care groups was small, and the benefit associated with prenatal care was no greater among women with pregnancy complications. CONCLUSIONS. The lower utilization of prenatal care by poorer women accounted for a small proportion of the difference in birthweight. Socioeconomic differences in birthweight are primarily attributable to factors not directly influenced by early prenatal medical care.     

High prevalence of vitamin D insufficiency and its association with BMI-for-age among primary school children in Kuala Lumpur,Malaysia

Background  

Deficiencies of micronutrients can affect the growth and development of children. There is increasing evidence of vitamin D deficiency world-wide resulting in nutritional rickets in children and osteoporosis in adulthood. Data on the micronutrient status of children in Malaysia is limited. The aim of this study was to determine the anthropometric and micronutrient status of primary school children in the capital city of Kuala Lumpur.