Airway function among Inuit primary school children in far northern Quebec

Respiratory health and its determinants among Nunavimmiut: results from the Qanuilirpitaa? 2017 Nunavik Health Survey

OBJECTIVES

Respiratory diseases are the leading cause of hospitalization in Nunavik (northern Québec, Canada) and contribute to disparities in life expectancy with the rest of Canada. As part of Qanuilirpitaa? 2017, a cross-sectional population-based health survey, we sought to describe the prevalence of respiratory health indicators, including the first estimate of airway obstruction based on spirometry in an Inuit population, and explore their associated characteristics.

METHODS

We analyzed data from 1296 participants aged 16 years and older, using multivariate logistic regression to assess characteristics associated with spirometry-determined airway obstruction and self-reported respiratory symptoms, i.e., wheezing in the last year and chronic cough during at least 3 months.

RESULTS

In this relatively young population (83% aged 16 to 54), the prevalences of wheezing, chronic cough, and airway obstruction were, respectively, 27% (95% CI 24-30), 21% (18-23), and 17% (14-20). These estimates are prone to biases due to the relatively low participation rate (about 37%). The most consistent associations were with smoking (≥ 15 pack-years; odds ratio [OR] 3.13, 3.39, and 2.86 for the three indicators, respectively) and food security (OR 0.55 with wheezing and OR 0.26 with chronic cough), as defined in the Household Food Security Survey Module. Wheezing was also associated with allergic sensitization to dogs (2.60) and obesity (2.18). Chronic cough was associated with respiratory infections during childhood (2.12), housing in need of major repairs (1.72), and housing crowding (1.50), and was negatively associated with participation to traditional activities (0.62) and going on the land (0.64). Airway obstruction was associated with being underweight (3.84) and post-secondary education (0.40). Among young adults and women, wheezing was also associated with any inhalation of solvents for recreational purposes during their lifetime (2.62 and 1.56, respectively), while airway obstruction was associated with regular marijuana use (2.22 and 1.84, respectively).

CONCLUSION

Smoking and food insecurity are both highly prevalent and strongly associated with respiratory symptoms in Nunavik. Together with essential smoking prevention and cessation programs, our findings suggest that solving food security and housing crises, improving socioeconomic conditions, and promoting traditional lifestyle may improve respiratory health in Nunavik.

Household determinants of biocontaminant exposures in Canadian homes

Exposure to biocontaminants, such as dust mites, animal dander, bacteria, and mold, is associated with a range of health effects. This study identified household characteristics associated with indoor biocontaminant loadings in four Canadian cities. Floor dust was collected in 290 Canadian homes in Edmonton, Halifax, Montreal, and Windsor. The dust samples were analyzed for house dust mite allergens (Der f 1 and Der p 1), cat allergen (Fel d 1), cockroach allergen (Bla g 1), beta-(1,3)-D-glucan, and endotoxin. Household information was obtained through questionnaires and home inspections. We performed univariate and multivariate analyses to identify household determinants of biocontaminant loadings and mold odor presence. We observed large regional variations for all biocontaminants, except for cockroach allergen. The ranges of the contaminants measured in loadings and concentrations were similar to that of previous Canadian studies. Household characteristics including presence of carpeting, low floor cleaning frequency, older home age, presence of pets, and indoor relative humidity above 45% were positively associated with the presence of multiple indoor biocontaminants. High floor cleaning frequency and use of dehumidifiers were negatively associated with the presence of multiple indoor biocontaminants. Mold odor was positively associated with older home age, past water damage, and visible mold growth.

Immune metabolism in allergies, does it matter?-A review of immune metabolic basics and adaptations associated with the activation of innate immune cells in allergy

Type I allergies are pathological, type 2 inflammatory immune responses against otherwise harmless environmental allergens that arise from complex interactions between different types of immune cells. Activated immune cells undergo extensive changes in phenotype and function to fulfill their effector functions. Hereby, activation, differentiation, proliferation, migration, and mounting of effector responses require metabolic reprogramming. While the metabolic changes associated with activation of dendritic cells, macrophages, and T cells are extensively studied, data about the metabolic phenotypes of the other cell types critically involved in allergic responses (epithelial cells, eosinophils, basophils, mast cells, and ILC2s) are rather limited. This review briefly covers the basics of cellular energy metabolism and its connection to immune cell function. In addition, it summarizes the current state of knowledge in terms of dendritic cell and macrophage metabolism and subsequently focuses on the metabolic changes associated with activation of epithelial cells, eosinophils, basophils, mast cells, as well as ILC2s in allergy. Interestingly, the innate key cell types in allergic inflammation were reported to change their metabolic phenotype during activation, shifting to either glycolysis (epithelial cells, M1 macrophages, DCs, eosinophils, basophils, acutely activated mast cells), oxidative phosphorylation (M2 macrophages, longer term activated mast cells), or fatty acid oxidation (ILC2s). Therefore, immune metabolism is of relevance in allergic diseases and its connection to immune cell effector function needs to be considered to better understand induction and maintenance of allergic responses. Further progress in this field will likely improve both our understanding of disease pathology and enable new treatment targets/strategies.

Domestic Risk Factors for Atopic and non-Atopic Asthma in First Nations Children Living in Saskatchewan, Canada

Both allergic and non-allergic asthma phenotypes are thought to vary by specific housing and other indoor environmental conditions. This study evaluated risk factors for allergic asthma phenotypes in First Nation children, an understudied Canadian population with recognized increased respiratory morbidity. We conducted a cross-sectional survey with a clinical component to assess the respiratory health of 351 school-age children living on two rural reserve communities. Asthma was defined as parental report of physician diagnosed asthma or a report of wheeze in the past 12 months. Atopy was determined by a ≥ 3-mm wheal response to any of six respiratory allergens upon skin prick testing (SPT). Important domestic and personal characteristics evaluated included damp housing conditions, household heating, respiratory infections and passive smoking exposure. Asthma and atopy prevalence were 17.4% and 17.1%, respectively. Of those with asthma, 21.1% were atopic. We performed multivariate multinomial logistic regression modelling with three outcomes: non-atopic asthma, atopic asthma and no asthma for 280 children who underwent SPT. After adjusting for potential confounders, children with atopic asthma were more likely to be obese and to live in homes with either damage due to dampness (p < 0.05) or signs of mildew/mold (p = 0.06). Both natural gas home heating and a history of respiratory related infections were associated with non-atopic asthma (p < 0.01). Domestic risk factors for asthma appear to vary by atopic status in First Nations children. Determining asthma phenotypes could be useful in environmental management of asthma in this population.

The Influence of Dietary Fatty Acids on Immune Responses

Diet-derived fatty acids (FAs) are essential sources of energy and fundamental structural components of cells. They also play important roles in the modulation of immune responses in health and disease. Saturated and unsaturated FAs influence the effector and regulatory functions of innate and adaptive immune cells by changing membrane composition and fluidity and by acting through specific receptors. Impaired balance of saturated/unsaturated FAs, as well as n-6/n-3 polyunsaturated FAs has significant consequences on immune system homeostasis, contributing to the development of many allergic, autoimmune, and metabolic diseases. In this paper, we discuss up-to-date knowledge and the clinical relevance of the influence of dietary FAs on the biology, homeostasis, and functions of epithelial cells, macrophages, dendritic cells, neutrophils, innate lymphoid cells, T cells and B cells. Additionally, we review the effects of dietary FAs on the pathogenesis of many diseases, including asthma, allergic rhinitis, food allergy, atopic dermatitis, rheumatoid arthritis, multiple sclerosis as well as type 1 and 2 diabetes.

Evaluation of eczema, asthma, allergic rhinitis and allergies among the grade-7 children of Iqaluit

Background

Little is known about the prevalence of asthma, allergic rhinitis, eczema and allergies among Canadian Inuit children, especially those living in the arctic and subarctic areas.

Methods

A cross-sectional study among grade seven students attending schools in Iqaluit, the capital city of Nunavut, was conducted during the 2016/2017 school year. We used the International Study of Allergy and Asthma in Children (ISAAC) questionnaire with added questions relevant to the population. In addition, skin prick tests (SPT) were conducted to test for sensitization to common food and environmental allergens.

Results

The prevalence of current asthma is 5.2%, all of them were males and 2/3 of them were Inuit and all had a previous respiratory hospitalization. Past asthma prevalence is 8.6%, 60% males and 60% Inuit. There was an inverse relationship to crowdedness possibly as a confounding factor because of getting a higher prevalence among the non-Inuit who usually live in less crowded houses. Current allergic rhinitis prevalence is 8.6%, 60% of the cases were among the mixed Inuit/Caucasian ethnicity while no cases among the non-Inuit, there was a female predominance 3:2. Past history of allergic rhinitis prevalence is 10.3%, half of the cases were among the mixed ethnicity (5.2% of that ethnicity) followed by Inuit (3.4%) and non-Inuit (1.7%), female: Male ratio 1:1. Current eczema prevalence was 27.6%, with half of the cases among the mixed ethnicity (13.8% of that group), followed by Inuit (8.6%). There was a female predominance with protective effect of exclusive breastfeeding. Past eczema prevalence 34.5%, with half of the cases were among the mixed ethnicity (17.2% of that group), followed by Inuit (10.3%). There was a female predominance. We noted a high rate of sensitization to Cat at 29.2%, most of the cases were among the mixed ethnicity, while absent sensitization to other common inhalant allergens.

Conclusion

While being cautious about firm conclusions due to the small sample size and power, the noticed variations in the prevalence and risk factors of asthma, allergic rhinitis and eczema among different ethnicities living at the same subarctic environment might be related to several possible explanations like genetic, gene-environment interaction and/or lifestyle factors, it was out of the scope of this study to determine the causality of such variation in prevalence, which emphasizes the need for further investigation.

Global prevalence of exercise-induced bronchoconstriction in childhood: A meta-analysis

AIM

This systematic review and meta-analysis aimed to estimate the global prevalence of exercise-induced bronchoconstriction (EIB) in children and adolescents.

METHOD

We searched PubMed, Google Scholar, and the Virtual Health Library-BIREME from inception to December 23, 2017. We selected observational studies that reported the prevalence of EIB (diagnosed by exercise challenge test) in children and adolescents aged 5-18 years. We conducted random-effects meta-analyses to estimate the pooled prevalence of EIB and 95% CI.

RESULTS

We included 66 studies (55 696 participants, 5670 cases of EIB) in the review, of which 33 in general population of children and adolescents, 10 in child and adolescent athletes and 23 in children and adolescents with asthma. The global mean prevalence of EIB in the general population of children and adolescents was 9% (IC95%: 8-10%), with a higher rate (12%) in Asia-Pacific and America. The mean prevalence of EIB was 15% (95% CI: 9-21%) in child and adolescent athletes, and 46% (95% CI: 39-53%) in children and adolescents with asthma. We estimated that, globally, around 16.5 million (95% CI: 15-18 million) children and adolescents up to 18 years of age may have EIB.

CONCLUSION

EIB in childhood should be considered as a global public health problem that needs more attention. The substantial heterogeneity between studies highlights the need for evidence-based guidelines for diagnosis of EIB in this age group.

Evaluation of eczema, asthma, allergic rhinitis and allergies among the Grade-1 children of Iqaluit

Background

Little is known about the prevalence of asthma, allergic rhinitis, eczema and allergies among Canadian Inuit children, especially those living in the arctic and subarctic areas.

Methods

A cross-sectional study among Grade 1 students attending schools in Iqaluit, the capital of Nunavut, was conducted during the 2015/2016 school year. We used the International Study of Allergy and Asthma in Children questionnaire with added questions relevant to the population. In addition, skin prick tests were conducted to test for sensitization to common food and environmental allergens.

Results

The prevalence of current asthma was 15.9% (> 2:1 males) with the highest prevalence among those with any non-Inuit heritage at 38.5%. The prevalence of current and past allergic rhinitis was 6.8%, also predominant among males, with the lowest prevalence among the mixed ethnicity. Home crowdedness was inversely related to past asthma. Being ever outside Nunavut was associated with higher prevalence of current and past asthma. No statistically significant relationship was found with passive smoking or exclusive breast feeding during the first 4 months of life. The current eczema prevalence was 20.5%, with the highest prevalence recorded among the Inuit at 25% compared to 15.4% among the mixed ethnicity and 14.3% among the non-Inuit. We noted a high rate of sensitization to cat at 26.7% while absent sensitization to other common inhalant allergens.

Conclusion

Variations in the prevalence and risk factors of asthma, allergic rhinitis and eczema among different ethnicities living at the same subarctic environment may be related to genetic, gene-environment interaction and/or lifestyle factors that require further investigation.

Prevalence of childhood eczema and food sensitization in the First Nations reserve of Natuashish, Labrador, Canada

Background

The Mushua Innu of Natuashish, Labrador, Canada seem to have a high rate of childhood eczema. Anecdotally this problem seems to be more common now than 20 years ago. There has been speculation that this could be related to food sensitization that may have arisen coincident with a move away from a traditional Innu diet. We undertook to assess the prevalence and severity of pediatric eczema in Natuashish (population 792), and investigate the level of sensitization to common food antigens.

Methods

Over a three-month period we performed a population survey of all children in the community from the ages of 2–12 inclusive. The one-year prevalence of eczema was assessed using the United Kingdom Working Party’s diagnostic criteria, and graded on the Nottingham Severity Scale. All children with eczema and twice as many age/sex matched controls were offered complete blood counts, total IgE, and food specific IgE levels for egg white, cow’s milk protein and wheat.

Results

One hundred and eighty two (95% of the eligible children) were assessed. Of the 182 children examined eczema was diagnosed in 30 (16.5%) - 22 females and 8 males. The majority of children with eczema (20/30) were classified as being in the moderate and severe category. Of the 22 with eczema and 40 controls who consented to venipuncture all but 3 had IgE levels above the lab's reference range. Food specific antibody assays showed that 32, 23, and 5 percent of children with eczema were sensitized to egg, milk, and wheat respectively. None of the controls were sensitized.

Conclusions

The children of Natuashish, Labrador have a high rate of eczema, much of it graded as moderate or severe. IgE levels were markedly elevated in children with and without eczema, with average values at least ten-fold higher than other populations. There is no evidence of an unusual amount of sensitization to egg, milk or wheat.

Prevalence and risk factors of asthma in off-reserve Aboriginal children and adults in Canada

Only a few studies have investigated asthma morbidity in Canadian Aboriginal children. In the present study, data from the 2006 Aboriginal Peoples Survey were used to determine the prevalence and risk factors for asthma in Canadian Aboriginal children six to 14 years of age and adults 15 to 64 years of age living off reserve. The prevalence of asthma was 14.3% in children and 14.0% in adults. Children and adults with Inuit ancestry had a significantly lower prevalence of asthma than those with North American Indian and Métis ancestries. Factors significantly associated with ever asthma in children included male sex, allergy, low birth weight, obesity, poor dwelling conditions and urban residence. In adults, factors associated with ever asthma varied among Aboriginal groups; however, age group, sex and urban residence were associated with ever asthma in all four Aboriginal groups. The prevalence of asthma was lower in Aboriginal children and higher in Aboriginal adults compared with that reported for the Canadian population. Variation in the prevalence of and risk factors for asthma among Aboriginal ancestry groups may be related to genetic and environmental factors that require further investigation.

Severe early lower respiratory tract infection is associated with subsequent respiratory morbidity in preschool Inuit children in Nunavut, Canada

BACKGROUND

Inuit children in Nunavut, Canada, have high rates of lower respiratory tract infection (LRTI) early in life. Whether this commonly results in chronic respiratory symptoms later in life is unknown.

METHODS

A cross-sectional survey of 3- to 5-years-old Inuit children was conducted in all three regions of Nunavut, as part of the "Qanuippitali, what about us, how are we?" survey.

RESULTS

Reported chronic cough and wheezing were common in preschool Inuit children, although reported asthma diagnosed by a healthcare professional was uncommon. The presence of smokers in the home tended to be associated with severe LRTI in the first 2 years of life. Reported wheezing as well as reported bronchitis or pneumonia in the previous 12 months was significantly associated with severe LRTI in the first 2 years of life. Reported wheezing was also strongly associated with reported bronchitis or pneumonia in the past 12 months. The prevalence of chronic moist cough could not be clearly assessed, due to limitations in the questionnaire.

INTERPRETATION

Severe LRTI in the first 2 years of life was associated with ongoing respiratory morbidity in preschool Inuit children, although symptoms appeared to lessen in severity over time.

Heat recovery ventilators prevent respiratory disorders in Inuit children

Inuit infants have high rates of reported hospitalization for respiratory infection, associated with overcrowding and reduced ventilation. We performed a randomized, double-blind, placebo controlled trial to determine whether home heat recovery ventilators (HRV) would improve ventilation and reduce the risk of respiratory illnesses in young Inuit children. Inuit children under 6 years of age living in several communities in Nunavut, Canada were randomized to receive an active or placebo HRV. We monitored respiratory symptoms, health center encounters, and indoor air quality for 6 months. HRVs were placed in 68 homes, and 51 houses could be analyzed. Subjects had a mean age of 26.8 months. Active HRVs brought indoor carbon dioxide concentrations to within recommended concentrations. Relative humidity was also reduced. Use of HRV, compared with placebo, was associated with a progressive fall in the odds ratio for reported wheeze of 12.3% per week (95%CI 1.9-21.6%, P = 0.022). Rates of reported rhinitis were significantly lower in the HRV group than the placebo group in month 1 (odds ratio 0.20, 95%CI 0.058-0.69, P = 0.011) and in month 4 (odds ratio 0.24, 95%CI 0.054-0.90, P = 0.035). There were no significant reductions in the number of health center encounters, and there were no hospitalizations. Use of HRVs was associated with in improvement in air quality and reductions in reported respiratory symptoms in Inuit children.

PRACTICAL IMPLICATIONS

Reduced ventilation is common in the houses of Inuit children in arctic Canada, and is associated with an increased risk of respiratory infection. Installation of HRV brings indoor carbon dioxide concentration, as a marker of adequate ventilation, to within recommended concentrations, although relative humidity is also reduced. Installation of HRV is associated with improvements in indoor air quality, and a reduced risk of wheezing and rhinitis not associated with cold air exposure in young Inuit children. Further research is required to explore traditional Inuit cultural attitudes about air movement in dwellings.

Chronic respiratory symptoms and diseases among indigenous children

Children from Indigenous populations experience more frequent, severe, and recurrent lower respiratory infections as infants and toddlers. The consequences of these infections are chronic lung disorders manifested by recurrent wheezing and chronic productive cough. These symptoms are aggravated more frequently by active and passive tobacco smoke exposure among Indigenous groups. Therapies for these symptoms, although not specific to children of Indigenous origins, are described as is the evidence for their use.

Risk factors and viruses associated with hospitalization due to lower respiratory tract infections in Canadian Inuit children : a case-control study

OBJECTIVES

To examine risk factors for lower respiratory tract infections (LRTI) hospital admission in the Canadian Arctic.

METHODS

This was a case-control study during a 14-month period among children less than 2 years of age. Cases were admitted to the Baffin Regional Hospital in Iqaluit, Nunavut with LRTI. Controls were age matched and came from Iqaluit and 2 communities. Odds ratios (ORs) of hospital admission for LRTI were estimated through multivariate conditional logistic regression modeling for following risk factors: smoking in pregnancy, Inuit race, prematurity, adoption status, breast-feeding, overcrowding, and residing outside of Iqaluit. Viruses in nasophayngeal aspirates were sought at the time of each hospital admission.

RESULTS

There were 101 age-matched cases and controls. The following risk factors were significantly associated with an increased risk of admission for LRTI (adjusted OR): smoking in pregnancy (OR = 4.0; 95% CI: 1.1-14.6), residence outside of Iqaluit (OR = 2.7; 95% CI: 1.0 -7.2), full Inuit race (OR = 3.8; 95% CI: 1.1-12.8), and overcrowding (OR = 2.5, 95% CI: 1.1- 6.1). Non-breast-fed children had a 3.6-fold risk of being admitted for LRTI (95% CI: 1.2-11.5) and non-breast-fed adopted children had a 4.4-fold increased risk (95% CI: 1.1-17.6) when compared with breast-fed, nonadopted children. Prematurity was not associated with an increased risk of admission. Viruses were identified in 88 (72.7%) of admissions, with respiratory syncytial virus being identified in the majority of admissions, 62 (51.2%). Multiple viruses were isolated in 19 (15.7%) admissions.

CONCLUSIONS

Smoking during pregnancy, place of residence, Inuit race, lack of breast-feeding, and overcrowding were all independently associated with increased risk of hospital admission for LRTI among Inuit children less than 2 years of age. Future research on the role of adoption and genetics on the health of Inuit children are required.

The cost effectiveness of palivizumab in term Inuit infants in the Eastern Canadian Arctic

INTRODUCTION

Canadian, Inuit, full term infants have the highest rate of respiratory syncytial virus (RSV) infection globally, which results in substantial costs associated hospitalisation.

METHODS

Decision-analytical techniques were used to estimate the incremental cost-effectiveness ratio (ICER) for palivizumab compared to no prophylaxis for Inuit infants of all gestational age. The time horizon was that of life-time follow-up, and costs and effectiveness were discounted at 5% per year. Costs (2007 CAD$) for palivizumab, hospitalisation (including medical evacuation, intensive care unit [ICU]), physician visits, and transportation were calculated based on the Canadian payer's perspective. Benefits on decreasing RSV hospitalisation were expressed as quality-adjusted life-years (QALYs). One-way and probabilistic sensitivity analysis (PSA) were conducted, varying: mortality rates, utilities, length of stay in hospital and ICU.

RESULTS

For all of Baffin Island infants (<1 year), the ICER was $39,435/QALY. However, when infants were grouped by age and area of residence, those residing in Iqaluit (<1 year) had an ICER of $152,145/QALY, while those residing in rural areas (outside of Iqaluit) had an ICER of $24,750/QALY. Prophylaxis was a dominant strategy (cost saving) for rural infants under 6 months of age, with the PSA demonstrating that it was dominant 98% of the time.

CONCLUSIONS

The ICERs suggested that palivizumab is a cost-effective option for the prevention of RSV for Inuit infants on Baffin Island compared to no prophylaxis. Palivizumab is highly cost effective in Arctic infants <1 year of age specifically residing outside of Iqaluit and is a dominant strategy for those under 6 months of age in rural areas. However, palivizumab is not cost effective compared to no treatment for infants of all ages residing in Iqaluit.

Innovative approaches in public health research: applying life course epidemiology to aboriginal health research

A life course epidemiology approach embraces the complexity of disease risk and acknowledges the long-term effects of physical, social, psychological, and behaviour pathways, operating across an individual's life, a community's generation, and a population's development, on health and well-being. Researchers who adopt a life course epidemiology approach broaden their ability to understand, explain, and prescribe ways to mitigate the effects of chronic diseases and reduce risk factor development and interaction. Although there are many diseases that explicate the importance and usefulness of a life course approach for Aboriginal health research, this commentary focuses on the benefits for understanding chronic respiratory diseases in Aboriginal populations. The hope is that this will expose the benefits of a life course approach for the study of Aboriginal health research and draw attention to the need for well-rounded, high-quality Aboriginal respiratory health research.

Prevalence of asthma and risk factors for asthma-like symptoms in Aboriginal and non-Aboriginal children in the northern territories of Canada

BACKGROUND

Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children.

OBJECTIVE

To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada.

METHODS

Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months.

RESULTS

After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother's daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother's daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children.

CONCLUSIONS

Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.

Indoor air quality and the risk of lower respiratory tract infections in young Canadian Inuit children

BACKGROUND

Inuit infants have the highest reported rate of hospital admissions because of lower respiratory tract infections in the world. We evaluated the prevalence of reduced ventilation in houses in Nunavut, Canada, and whether this was associated with an increased risk of these infections among young Inuit children.

METHODS

We measured ventilation in 49 homes of Inuit children less than 5 years of age in Qikiqtaaluk (Baffin) Region, Nunavut. We identified the occurrence of lower respiratory tract infections using a standardized questionnaire. Associations between ventilation measures and lower respiratory tract infection were evaluated using multiple logistic regression models.

RESULTS

The mean number of occupants per house was 6.1 people. The mean ventilation rate per person was 5.6 L/s (standard deviation [SD] 3.7); 80% (37/46) of the houses had ventilation rates below the recommended rate of 7.5 L/s per person. The mean indoor carbon dioxide (CO2) concentration of 1358 (SD 531) ppm was higher than the recommended target level of 1000 ppm. Smokers were present in 46 homes (94%). Of the 49 children, 27 (55%) had a reported history of lower respiratory tract infection. Reported respiratory infection was significantly associated with mean CO2 levels (odds ratio [OR] 2.85 per 500-ppm increase in mean indoor CO2, 95% confidence interval [CI] 1.23-6.59) and occupancy (OR 1.81 for each additional occupant, 95% CI 1.14-2.86).

INTERPRETATION

Reduced ventilation and crowding may contribute to the observed excess of lower respiratory tract infection among young Inuit children. The benefits of measures to reduce indoor smoking and occupancy rates and to increase ventilation should be studied.

Autism, asthma, inflammation, and the hygiene hypothesis

Inflammation and the genes, molecules, and biological pathways that lead to inflammatory processes influence many important and disparate biological processes and disease states that are quite often not generally considered classical inflammatory or autoimmune disorders. These include development, reproduction, aging, tumor development and tumor rejection, cardiovascular pathologies, metabolic disorders, as well as neurological and psychiatric disorders. This paper compares parallel aspects of autism and inflammatory disorders with an emphasis on asthma. These comparisons include epidemiological, morphometric, molecular, and genetic aspects of both disease types, contributing to a hypothesis of autism in the context of the immune based hygiene hypothesis. This hypothesis is meant to address the apparent rise in the prevalence of autism in the population.

Unchanged asthma prevalence during 1990-1999 in rural Alaska Natives

OBJECTIVES

The prevalence of asthma has been increasing throughout the world, but the reasons for the increase are unclear. Some have hypothesized that the increase is due to industrial and agricultural pollutants in urban and rural areas, respectively. The objective of this research was to determine if the prevalence of asthma has increased in a remote area of Alaska where the population lives a subsistence lifestyle and is not exposed to such pollution.

STUDY DESIGN

Retrospective review of medical records to determine the prevalence of asthma.

METHODS

We reviewed medical records of 1200 children, aged 0-10 years, who lived in the Yukon-Kuskokwum Delta (YKD) region of western Alaska between 1990 and 1999. The entire YKD population receives health care from a single medical system, so records provide a complete picture of each patient's health care. Data collected from the medical records included demographics, and the presence or absence of a diagnosis of asthma or reactive airway disease (RAD).

RESULTS

Over the 10-year period from 1990-1999, there was no significant change in the percentage of children who had a diagnosis of asthma (2.0% in 1990 and 3% in 1999), or RAD (9.6% in 1990 and 9.6% in 1999).

CONCLUSIONS

In a population of children not exposed to urban industrial, or rural agricultural pollutants, there was no change in the prevalence of wheezing or asthma between 1990 and 1999.

Relationship between IgE and specific aeroallergen sensitivity in Alaskan native children

BACKGROUND

The relationship between atopic disease and serum IgE levels varies among populations and geographic regions. The close association of atopy with IgE may not occur in subarctic populations as it does in developed countries in temperate climates.

OBJECTIVE

To evaluate the relationship between total and specific IgE concentrations and clinical atopy in 5- to 8-year-old Alaskan native children.

METHODS

Medical record reviews, interviews, physical examinations, serum IgE measurements, and radioallergosorbent testing (RAST) were performed.

RESULTS

The IgE geometric mean was 122.1 IU/mL. Fifty-eight percent of patients had IgE levels greater than 70 IU/mL, and 17% had levels greater than 1,000 IU/mL; 14% had RAST values greater than 0.35 kU/L. Both IgE levels greater than 70 IU/mL and greater than 1,000 IU/mL were associated with RAST values greater than 0.35 IU/L (P = .004) and early wheezing (P = .005) but not with current wheezing, asthma, eczema, or a history of allergies. A RAST value greater than 3.51 kU/L was associated with eczema (P = .04) but not with allergies or wheezing. Children with current wheezing were more likely to have allergies (P = .03) but not eczema, an IgE level greater than 70 IU/mL, or a positive RAST value. Children hospitalized with respiratory syncytial virus (RSV) were not more likely than controls to have current wheezing.

CONCLUSIONS

Elevated serum IgE concentrations, including levels greater than 1,000 IU/mL, are common among Alaskan native children; positive RAST reactions to aeroallergens are not. The IgE levels do not relate to wheezing, eczema, a history of allergies, or past hospitalization for RSV infection but likely reflect infections other than RSV and environmental factors in subarctic indigenous populations.

Indoor air quality risk factors for severe lower respiratory tract infections in Inuit infants in Baffin Region, Nunavut: a pilot study

Inuit infants have extremely high rates of lower respiratory tract infection (LRTI), but the causes for this are unclear. The aims of this study were to assess, in young Inuit children in Baffin Region, Nunavut, the feasibility of an epidemiologic study of the association between indoor air quality (IAQ) and respiratory health; to obtain data on IAQ in their housing; and to identify and classify risk factors for LRTI. Twenty houses in Cape Dorset, Nunavut with children below 2 years of age, were evaluated using a structured housing inspection and measurement of IAQ parameters, and a respiratory health questionnaire was administered. Twenty-five percent of the children had, at some time, been hospitalized for chest illness. Houses were very small, and had a median of six occupants per house. Forty-one percent of the houses had a calculated natural air change rate <0.35 air changes per hour. NO(2) concentrations were within the acceptable range. Smokers were present in at least 90% of the households, and nicotine concentrations exceeded 1.5 microg/m(3) in 25% of the dwellings. Particulates were found to be correlated closely with nicotine but not with NO(2) concentrations, suggesting that their main source was cigarette smoking rather than leakage from furnaces. Mattress fungal levels were markedly increased, although building fungal concentrations were low. Dust-mites were virtually non-existent. Potential risk factors related to IAQ for viral LRTI in Inuit infants were observed in this study, including reduced air exchange and environmental tobacco smoke exposure. Severe lower respiratory tract infection is common in Inuit infants. We found reduced air change rates and high occupancy levels in houses in Cape Dorset, which may increase the risk of respiratory infections. This suggests the measures to promote better ventilation or more housing may be beneficial. Further health benefits may be obtained by reducing bed sharing by infants and greater turnover of mattresses, which were found to have high levels of fungi.

Possible reasons for lack of effect of allergen avoidance in atopy-prone infants and sensitive asthmatic patients

The basic paradigm that allergen exposure produces atopic sensitization, and that continued exposure leads to clinical asthma throughout the development of airway inflammation and bronchial hyperreactivity has been challenged. However, because it was observed that epidemiological evidence suggests that around 40% of asthma cases are attributable to atopy (even using restrictive criteria), the obvious corollary is that if allergen avoidance begins before the onset of sensitization (primary prevention), then it should be associated with a reduced number of new cases of the disease. However, there are conflicting results regarding the effect of allergen avoidance on primary prevention of atopic sensitization and asthma onset. Instead, more uniform and positive results are available from secondary prevention studies. Secondary prevention obviously is an attractive opportunity for pediatricians who may recognize the patients who might benefit from these interventions simply by screening for food allergy in young children with atopic dermatitis. The conflicting results of tertiary prevention are most frequently observed in adult patients and sometimes result from incomplete avoidance of allergens responsible for the sensitization.

Exposure of adult mice to environmental tobacco smoke fails to enhance the immune response to inhaled antigen

Epidemiologic evidence supports a role for environmental tobacco smoke (ETS) in the occurrence and severity of allergies/asthma. However, neither the precise combination of ETS and allergen exposure nor the mechanism (or mechanisms) by which these factors interact and contribute to asthma induction is known. Animal model studies have failed to establish a convincing relationship between ETS exposure and asthma induction, perhaps because of methodological inadequacies. Here, we tested the hypothesis that ETS inhalation would provoke an asthmatic response by overcoming normal airway tolerance to inhaled antigens. Our protocol combined daily ETS exposure with nose-only sensitization to ovalbumin. Three strains of mice were tested, each with a different level of susceptibility to airway hypersensitivity. Immunological responses were assessed by immunoglobulin production. Airway inflammation was assessed by bronchoalveolar lavage differentials and lung histopathology. Airway hyperresponsiveness was determined by methacholine challenge. The mice produced ovalbumin-specific antibodies following ovalbumin exposure in a strain-dependent manner. Only the A/J mice produced detectable levels of ovalbumin-specific immunoglobulin (Ig) E. Both A/J and BALB/c mice produced ovalbumin-specific IgG1 antibodies. The C57Bl/6 mice did not produce detectable levels of antibodies. The A/J mice also exhibited airway inflammation following ovalbumin exposure. Neither the C57Bl/6 nor the BALB/c mice exhibited signs of airway inflammation. Exposure to ETS failed to enhance ovalbumin-specific antibody production, airway inflammation, or hyperresponsiveness. Together these results indicate that ETS exposure accompanied by nose-only allergen sensitization fails to overcome aerosol tolerance in adult mice.

Lung function in Greenlandic and Danish children and adolescents

Respiratory morbidity in Inuit children is high. However, little is know regarding lung function measures in this population. The forced expiratory volumes in one second (FEV(1)) and forced vital capacity (FVC) in 888 Greenlandic Inuits (N=888) and Danes (N=477) aged 6-18 years were compared. Furthermore, associations between level of lung function and atopy and lifestyle factors were estimated in Greenlanders. The effect of height on FEV(1) and FVC was significantly different in Greenlanders and Danes, this difference in lung function increased with increasing height, and could not be explained by differences in age weight and BMI. Thus, Greenlanders taller than 130 cm had up to 300-400 ml higher FEV(1) and FVC compared with Danes of the same height. Among Greenlanders, those living in settlements had the highest levels of both FEV(1) and FVC. Greenlanders had elevated levels of FEV(1) and FVC compared with Danes. The Inuit having a shorter limb length in relation to trunk height may account for these differences. However, our finding that Greenlanders living in settlements had the highest lung function level also suggests a possible role of factors in the traditional Greenlandic lifestyle.

Presentation and treatment of asthma among native children in southwest Alaska delta

Our objective was to determine if a different presentation of asthma among Eskimo children in southwest Alaska influenced treatment for asthma. Data regarding symptoms, medication use, and hospitalization were obtained from the medical records of 58 Eskimo children diagnosed with asthma. Half of the children also had a diagnosis of chronic lung disease (CLD), and 57% had a history of allergies. CLD was associated with significantly more visits for wheeze (P=0.02), asthma (P <0.005), and lower respiratory tract illnesses (P <0.005), and a greater incidence (P <0.005) and frequency (P <0.005) of hospitalizations. Allergy status showed no similar relation with utilization of health services. Inhaled corticosteroids were prescribed for a minority (38%) of these asthmatic children. Allergic children tended to be more likely to receive inhaled steroids, and they received significantly more prescriptions for inhaled steroids compared to children without allergies. Those with CLD only were no more likely to receive inhaled steroids than other children, despite their higher incidence of hospitalization. Although the proportion of children with CLD or allergy did not differ significantly by village, there were significant regional differences in healthcare utilization and medication use. In conclusion, while CLD was the primary determinant of healthcare utilization among these native children with asthma, only allergic children with CLD were more likely to receive inhaled steroids.

Prevalence of asthma and chronic respiratory symptoms among Alaska Native children

STUDY OBJECTIVES

To quantify the prevalence and impact of chronic respiratory symptoms among predominantly Alaska Native (AN)/American Indian (AI) middle school students.

DESIGN

School-based prevalence assessment using the International Study of Asthma and Allergy in Children survey, with supplemental video material and added questions about productive cough, exposure to tobacco smoke, and the functional impact of symptoms.

SETTING

The Yukon-Kuskokwim delta region of western Alaska.

PARTICIPANTS

A total of 466 children in the sixth to ninth grades, 81% of whom are AN/AI (377 children).

INTERVENTIONS

No study intervention.

RESULTS

Among the 377 AN/AI children, 40% reported one of the following three categories of chronic respiratory disease: physician-diagnosed asthma, 7.4%; asthma-like symptoms (ALS) without an asthma diagnosis, 11.4%; and chronic productive cough (CPC) without asthma diagnosis or symptoms, 21.5%. Symptom prevalence differed substantially between the largest town in the region and rural villages. After an adjustment for demographic factors, exposure to environmental tobacco smoke, active tobacco smoking, and self-report of atopy, village residents were 63% less likely to have ALS (p = 0.009), and had a twofold greater risk of CPC (p < 0.001) compared to children living in the town. Children with respiratory symptoms experienced sleep disturbances and accessed clinic visits for respiratory problems more often than did asymptomatic children.

CONCLUSIONS

Chronic respiratory symptoms are very common among AN children. CPC is an important nonasthmatic respiratory condition in this population. The differing patterns of respiratory illness within this region may help to elucidate the specific risk factors for asthma and chronic bronchitis in children.

Stabilization of an increasing trend in physician-diagnosed asthma prevalence in Saskatchewan, 1991 to 1998

OBJECTIVES

To determine the prevalence of asthma, bronchitis, and COPD using the physician services database of the Saskatchewan Health Department from 1991 to 1998.

DESIGN

Descriptive population-based study.

SETTING

The Province of Saskatchewan, Canada.

PARTICIPANTS

Residents of Saskatchewan covered by universal health care in the province.

RESULTS

In all age groups, asthma prevalence increased between 1991 and 1995 and either was stable or declined between 1996 and 1998. Preschool children had the highest asthma prevalence during the study period, followed by children aged 5 to 14 years, young adults aged 15 to 34 years, and adults aged 35 to 64 years. Children aged 0 to 4 years and adults aged 35 to 64 years in the Registered Indian population had greater asthma prevalence than persons in other urban or rural populations during the study period. Asthma prevalence rates in rural populations were less than or similar to the rates of urban populations in all age groups during the study period. The prevalence of bronchitis was greater in the Registered Indian population than in urban and rural populations in all age groups throughout the study period. When persons who had visited a physician for bronchitis were excluded from the prevalence calculation, the original increases seen in asthma prevalence among very young children and older adults of Registered Indian origin disappeared, with the urban population having greater asthma prevalence in all age groups. In the Registered Indian population, adults aged 35 to 64 years had almost twofold increases in the prevalence of COPD in comparison to other Saskatchewan populations.

CONCLUSIONS

Asthma prevalence, which had been on the increase in the 1980s and early 1990s, was either stable or declining during the latter part of 1990s in Saskatchewan. Preschool children and older adults from the Registered Indian population had greater asthma prevalence than did those from other Saskatchewan populations. Asthma prevalence among the rural populations was either similar or lower in comparison to the rates for the urban populations in all age groups during the study period. Further research is required to elucidate the findings in this study.

The role of respiratory viruses in the origin and exacerbations of asthma

PURPOSE OF REVIEW

The present review focuses and comments on the increasing body of evidence correlating respiratory viral infections with asthma onset and exacerbations.

RECENT FINDINGS

Recent data suggest multiple and some time contrasting roles for viral infection in the origin of asthma. These data also indicate that the immune status of the host, including atopy, may interactively contribute to this process, conferring susceptibility or even resistance to the development of asthma in virus-infected individuals. In the presence of asthma, the role of viral infection in triggering exacerbations is clearly established. Chemokine and cytokine responses of the respiratory epithelium, a biased type 1/type 2 cytokine balance, defective costimulation, as well as abnormal neural control have been suggested as possible mechanisms. The importance of concurrent or synergistic effects of allergen exposure is currently under scrutiny.

SUMMARY

Viruses may initiate and certainly exacerbate asthma. Mild repeated infections early in life could also stimulate type 1 immune responses conferring protection from atopy and asthma. The host's immune status, the type of viral infection and the timing of exposure to various environmental stimuli are probably the key factors in this process. Mechanistic insights deduced from recent work should allow for the development of intervening strategies in the near future.

Asthma and COPD among aboriginals in Alberta, Canada

BACKGROUND

Aboriginals in Canada bear a disproportionately higher burden of some chronic illnesses than nonaboriginals. Although there is a greater prevalence of smoking, poor housing, and overcrowding in aboriginal than nonaboriginal communities, the rates of office and emergency visits for asthma and COPD among aboriginals are not well known.

STUDY OBJECTIVE

To determine whether aboriginals require higher rates of asthma and COPD emergency and office visits than nonaboriginals.

SETTING

Population-based cohort of people residing in Alberta, Canada (population 2.8 million) between April 1, 1996, and March 31, 1997.

DESIGN

Retrospective cohort study.

RESULTS

We observed that aboriginals were 2.1 times (95% confidence interval [CI], 2.0 to 2.2) and 1.6 times (95% CI, 1.6 to 1.6) more likely to have an emergency and office visit for asthma or COPD, respectively, when compared to age-matched and sex-matched nonaboriginals. However, they were 55% (95% CI, 52 to 58%) less likely to see a specialist and 66% (95% CI, 63 to 70%) less likely to undergo spirometry than nonaboriginals.

CONCLUSIONS

These findings indicate that aboriginals bear a disproportionately higher burden of asthma and COPD than nonaboriginals. However, lower use of spirometry and specialist services suggests that there might be access barriers to quality health care for aboriginals in Canada.

Atopic sensitization among children in an arctic environment

BACKGROUND

Asthma has been reported to be rare among Inuits, but so far total and specific IgE levels have never been determined in arctic populations.

OBJECTIVE

To determine the prevalence of atopy in children living in an arctic environment, and to examine whether atopy and total IgE levels were associated with parental place of birth, as a measure of ethnicity, and travel history.

MATERIAL AND METHODS

All schoolchildren in Sisimiut, a community on the West coast of Greenland, were screened for atopy. Blood samples were analysed for total IgE and for specific IgE against inhalant and food allergens. Information on place of birth of children and their parents was obtained from national registries. Information on travel history was obtained from self-administered questionnaires.

RESULTS

A total of 1031 schoolchildren aged 5 to 18 years had a blood sample drawn (85% of available children for the study). Of these, 151 (14.6%) children were sensitized to at least one inhalant allergen and 42 (4.1%) to at least one food allergen. Sensitization to grass was most common, whereas sensitization to mugwort, birch, animal-dander and house-dust mite was infrequent. Children whose parents were both born abroad had a higher risk of sensitization to inhalant allergens compared with children born of Greenlandic parents (OR = 8.6, 95% CI 2.8-27.1). Furthermore, children who had been abroad had a higher risk of sensitization towards pollen (OR = 1.6, 95% CI 1.0-2.5) and animal-dander (OR = 2.1, 95% CI 1.0-4.6) after adjustment for confounders. Both atopic and non-atopic children demonstrated high levels of total IgE (medians of 251 and 58 kU/L).

CONCLUSIONS

Compared with European findings Greenlandic children have high levels of total IgE but a low prevalence of allergic sensitization towards inhalant allergens. This may be due to a low genetic susceptibility to atopy and less allergen exposure, as well as to living conditions in an arctic environment.

Asthma hospitalization trends in Charleston, South Carolina, 1956 to 1997: twenty-fold increase among black children during a 30-year period

OBJECTIVE

The increase in asthma prevalence has been documented worldwide, affecting many races living in many different climates. Multiple studies have demonstrated that the most striking prevalence and morbidity of asthma in the United States has been in black children, but little research has determined the scale of the increase, or specifically when the disease became severe in this group. This study sought to determine exactly when the rise in asthma hospitalizations among black patients began and what the pattern of asthma hospitalizations has been in different races and age groups over a 40-year period in 1 urban area.

METHODS

A retrospective chart review of discharges from the Medical University of South Carolina was conducted from 1956 to 1997. Charts with the primary discharge diagnosis of asthma were examined for discharge date, race, and age group (0- to 4-year-olds, 5- to 18-year-olds, 19- to 50-year-olds, > or =51-year-olds). The diagnostic codes used were based on the International Classification of Diseases (ICD)-6, 1956-1957; ICD-7, 1958-1967; ICD-8, 1968-1978; and ICD-9, 1979-1997. Over the period studied, this hospital was the primary inpatient provider for children in this area, and the only provider for uninsured children. Between 1960 and 1990, the racial makeup of the area remained stable, as did the percentage of blacks living at the poverty level. The raw number of asthma discharges, rate per 10 000 discharges of the same race, and rate per 100 000 population in Charleston County were tabulated for each age group and racial category.

RESULTS

Over the time period examined, there has been a progressive increase in asthma hospitalizations in black individuals of all age groups and in whites under 18 years. The most striking increase has been in black children 0 to 18 years old (figure). The increase either as raw values or as a rate per 100 000 began around 1970, and was linear. This increase in black children discharged with asthma as a rate per 100 000 population was 20-fold: the rate increased from 18 in 1970 to 370 in 1997. Asthma discharges as a rate per 10 000 black children discharged increased by 24-fold from 1960 to 1997. Total discharges from the hospital increased from 49 000 to 128 000 per year over this period. Blacks made up only 28% of discharges in 1957, but that proportion increased to 56% in 1960 and remained relatively stable over the following 35 years. The increase seen in white children 0 to 18 years of age as a rate per 100 000 population was 5-fold and began around 1980. Both increases seem to be consistent over the time period studied, and continued to 1997. [figure: see text].

CONCLUSIONS

Among a predominantly poor black population living in a southern US city, there has been a steady increase in childhood asthma hospitalizations over the past 30 years. A significant although less dramatic rise has occurred in white children. Over this time period, although there have been many changes in lifestyle that could have contributed to this rise, there have been no major changes in housing conditions for poor patients. In addition, Medicaid coverage for children in South Carolina did not change significantly until 1999. The time course of these increases parallels increases reported in other Western populations, suggesting that there must be 1 or more common factors contributing to the rise. Many explanations have been offered for the changes in incidence and severity of asthma. The scale of the change, time course, and linearity of the increase in this study represent a challenge to many of the hypotheses proposed to explain this epidemic.

Atopic diseases in Sami and Norse schoolchildren living in northern Norway

Among children in the western world, atopic diseases are a major cause of morbidity. However, several prevalence studies have indicated that the frequency of these diseases displays both geographic and ethnic variations. In 1995, we conducted a questionnaire-based, cross-sectional survey in northern Norway. Atopic diseases among 8676 schoolchildren, aged 7-13 years, including 491 children with Sami ethnicity, were studied. The role of ethnicity (Sami/white Caucasian) was determined by comparing the reported atopic disease rate in each of the respective groups. In the areas under investigation (the cumulative incidence, the point prevalence of asthma and allergic rhinoconjunctivitis and the cumulative incidence of atopic dermatitis), the Sami children scored higher than the white Caucasian Norwegian children. The relative risks (RR) in Sami children were: current asthma RR = 2.01 [95% confidence interval (CI) 1.48-2.73]; current allergic rhinoconjunctivitis RR = 1.51 (95% CI 1.14-1.99); lifetime atopic dermatitis RR = 1.39 (95% CI 1.18-1.63). We thus conclude that there is an association between Sami ethnicity and asthma and allergy among schoolchildren in northern Norway.