Determinants Of Asthma Research Articles

DNA-dependent protein kinase inhibition blocks asthma in mice and modulates human endothelial and CD4+ T-cell function without causing severe combined immunodeficiency

We reported that DNA-dependent protein kinase (DNA-PK) is critical for the expression of nuclear factor κB-dependent genes in TNF-α-treated glioblastoma cells, suggesting an involvement in inflammatory diseases. We sought to investigate the role of DNA-PK in asthma. Cell culture and ovalbumin (OVA)- or house dust mite-based murine asthma models were used in this study. DNA-PK was essential for monocyte adhesion to TNF-α-treated endothelial cells. Administration of the DNA-PK inhibitor NU7441 reduced airway eosinophilia, mucus hypersecretion, airway hyperresponsiveness, and OVA-specific IgE production in mice prechallenged with OVA. Such effects correlated with a marked reduction in lung vascular cell adhesion molecule 1 expression and production of several cytokines, including IL-4, IL-5, IL-13, eotaxin, IL-2, and IL-12 and the chemokines monocyte chemoattractant protein 1 and keratinocyte-derived chemokine, with a negligible effect on IL-10/IFN-γ production. DNA-PK inhibition by gene heterozygosity of the 450-kDa catalytic subunit of the kinase (DNA-PKcs(+/-)) also prevented manifestation of asthma-like traits. These results were confirmed in a chronic model of asthma by using house dust mite, a human allergen. Remarkably, such protection occurred without causing severe combined immunodeficiency. Adoptive transfer of TH2-skewed OT-II wild-type CD4(+) T cells reversed IgE and TH2 cytokine production but not airway hyperresponsiveness in OVA-challenged DNA-PKcs(+/-) mice. DNA-PK inhibition reduced IL-4, IL-5, IL-13, eotaxin, IL-8, and monocyte chemoattractant protein 1 production without affecting IL-2, IL-12, IFN-γ, and interferon-inducible protein 10 production in CD3/CD28-stimulated human CD4(+) T cells, potentially by blocking expression of Gata3. These effects occurred without significant reductions in T-cell proliferation. In mouse CD4(+) T cells in vitro DNA-PK inhibition severely blocked CD3/CD28-induced Gata3 and T-bet expression in CD4(+) T cells and prevented differentiation of TH1 and TH2 cells under respective TH1- and TH2-skewing conditions. Our results suggest DNA-PK as a novel determinant of asthma and a potential target for the treatment of the disease.

Prenatal Dietary Determinants of Asthma and Related Allergic Disorders in Childhood

The rise in asthma and allergic disease in recent decades, with accompanying morbidity and healthcare costs, has placed these conditions on the forefront of public health challenges. Allergic disease manifests itself shortly after birth, suggesting that disease development may commence already during fetal life. The early origins of these conditions and the concomitant changes in dietary habits have led to the formulation of several hypotheses relating dietary intake during pregnancy to deviant developmental adaptations in the fetal immune system and lung growth. These hypotheses are further supported by the demonstrated involvement of many nutrients, including fatty acids, antioxidants, and food allergens, in immune system function and maturation. Understanding the potential in utero influence of these nutrients on child allergic disease risk will provide a unique window of opportunity for early prevention by guiding women and their children to better health.

Endotoxin as a determinant of asthma and wheeze among rural dwelling children and adolescents: a case-control study.

BackgroundThe association between endotoxin exposure and asthma is complex and has been associated with rural living. We examined the relationship between domestic endotoxin and asthma or wheeze among rural school-aged children (6–18 years) and assessed the interaction between endotoxin and other characteristics with these outcomes.MethodsBetween 2005 and 2007 we conducted a case–control study of children 6–18 years in the rural region of Humboldt, Canada. Cases (n = 102) reported doctor-diagnosed asthma or wheeze in the past year. Controls (n = 208) were randomly selected from children without asthma or wheeze. Data were collected to ascertain symptoms, asthma history and indoor environmental exposures (questionnaire), endotoxin (dust collection from the play area floor and child’s mattress), and tobacco smoke exposure (saliva collection). Statistical testing was completed using multiple logistic regression to account for potential confounders and to assess interaction between risk factors. A stratified analysis was also completed to examine the effect of personal history of allergy.ResultsAmong children aged 6–12 years, mattress endotoxin concentration (EU/mg) and load (EU/m2) were inversely associated with being a case [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.20-0.98; and OR = 0.38, 95% CI = 0.20-0.75, respectively]. These associations were not observed in older children or with play area endotoxin.ConclusionsOur results suggest that endotoxin exposure might be protective for asthma or wheeze. The protective effect is found in younger school-aged, non-allergic children. These results may help explain the inconsistencies in previous studies and suggest that the protective effects of endotoxin in the prevention of atopy and asthma or wheeze are most effective earlier in life.

Measurement and clinical significance of IL-8 、IL-13 and IL-18 in serum of patients with bronchial asthma

Objective To investigate the change and significance of IL-8,IL-13 and IL-18 level in serum of patients with bronchial asthma.Methods 45 patients with acute exacerbation of bronchial asthma were selected (acute group),and remission group 45 patients and 30 healthy persons (control group) were selected.The serum IL-8,IL-13 and IL-18 levels were measured respectively by ELISA.Results The serum IL-8,IL-13 and IL-18 levels in acute group were significantly higher than that in control group and remission group ( t =5.21,5.13,4.99,5.32,5.48,5.59,P ＜ 0.05 ) ; The serum IL-8,IL-13 and IL-18 levels in remission group were significantly higher than that in control group(t =4.18,4.71,4.89,P ＜0.05).Conclusion The levels of serum IL-8,IL-13 and IL-18 may be related to the severity of asthma attack.IL-8,IL-13 and IL-18 played important role in both pathogenesis and determination of asthma. Key words: Asthma; Interleukin-8 ; Interleukin-13 ; Interleukin-18

Determinants of asthma after severe respiratory syncytial virus bronchiolitis

The development of asthma after respiratory syncytial virus (RSV) bronchiolitis has been demonstrated in case-control studies, although the determinants of post-RSV asthma remain undefined. We sought to evaluate the potential determinants of physician-diagnosed asthma after severe RSV bronchiolitis during infancy. We enrolled 206 children during an initial episode of severe RSV bronchiolitis at 12 months of age or less in a prospective cohort study and followed these children for up to 6 years. In a subset of 81 children, we analyzed CCL5 (RANTES) mRNA expression in upper airway epithelial cells. Forty-eight percent of children had physician-diagnosed asthma before the seventh birthday. Independent determinants significantly associated with increased risk for physician-diagnosed asthma by the seventh birthday included maternal asthma (odds ratio [OR], 5.2; 95% CI, 1.7-15.9; P = .004), exposure to high levels of dog allergen (OR, 3.2; 95% CI, 1.3-7.7; P = .012), aeroallergen sensitivity at age 3 years (OR, 10.7; 95% CI, 2.1-55.0; P = .005), recurrent wheezing during the first 3 years of life (OR, 7.3; 95% CI, 1.2-43.3; P = .028), and CCL5 expression in nasal epithelia during acute RSV infection (OR, 3.8; 95% CI, 1.2-2.4; P < .001). White children (OR, 0.19; 95% CI, 0.04-0.93; P = .041) and children attending day care (OR, 0.18; 95% CI, 0.04-0.84; P = .029) had a decreased risk of physician-diagnosed asthma. Approximately 50% of children who experience severe RSV bronchiolitis have a subsequent asthma diagnosis. The presence of increased CCL5 levels in nasal epithelia at the time of bronchiolitis or the development of allergic sensitization by age 3 years are associated with increased likelihood of subsequent asthma.

Roles of pollution in the prevalence and exacerbations of allergic diseases in Asia

The prevalence of asthma and allergic diseases has been found to be increasingly rapidly, especially in developing countries. Environmental factors have been found to be important contributors to the manifestations of allergic diseases. Air pollution has been extensively studied in different regions of the world. The levels of ambient air pollutants in many Asian countries are very high when compared with those in developed Western countries. However, the prevalence of asthma was relatively low across many Asian countries. Many studies have clearly documented that environmental air pollution is an important factor resulting in exacerbations of asthma. In particular, levels of traffic-related pollutants are increasing rapidly across many Asian countries in parallel with the level of urbanization and economic development. The loss of protective factors associated with a rural environment will further contribute to the adverse effect on patients with allergic diseases such as asthma. In this review the roles of air pollution were examined in relation to the inception and exacerbations of allergic diseases in Asia.

Molds, parental atopy and pediatric incident asthma

To assess the independent and joint effects of parental atopy and exposure to molds on the development of asthma in childhood, the authors conducted a cohort-based, incident case-control study in 2008. The case group consisted of 188 children with new asthma, and the control group (n=376) was matched one to two for age and sex. The outcome of interest was the development of asthma during the study period. The studied determinants were parental atopy and three indicators of exposure including histories of water damage, presence of visible molds, and perceived mold odor in the home at baseline in 2002. In conditional logistic regression adjusting for confounding, parental atopy [adjusted odds ratio (aOR) 3.29, 95% CI 2.19-4.94] and the presence of mold odor (aOR 2.09, 95% CI 1.30-3.37) and visible mold (aOR 1.76, 95% CI 1.18-2.62) were independent determinants of incident asthma, and apparent interaction in additive scale was observed. Our finding suggests that the interaction between parental atopy and molds may play a role in the development of asthma in children. Our study strengthens the evidence for the roles of indoor dampness problem and parental atopy as determinants of asthma in children. Furthermore, the interaction between parental atopy and exposure to molds suggests a role for the development of childhood asthma, i.e., the children whose parents had atopic disease and molds exposure are more susceptible to develop asthma.

Desigualdades regionais na prevalência de diagnóstico de asma em crianças: uma análise da Pesquisa Nacional por Amostra de Domicílios, 2003

The aim of this study was to estimate the prevalence of asthma diagnosis in Brazilian children and to analyze socio-demographic inequalities between the South and Northeast regions of the country. Data for children under 10 years of age were analyzed from the 2003 National Household Sample Survey, or PNAD (n = 69,796). Socioeconomic characteristics, the child's gender and age, and the parent or guardian's skin color were the independent variables investigated through unconditional multiple logistic regression. Prevalence of asthma diagnosis was 8.5% in Brazil as a whole (95%CI: 7.7-8.5) and 12.6% (95%CI: 11.6-13.5) and 4.4% (95%CI: 4.0-4.8) in the South and Northeast, respectively. After adjustment, children from 3 to 7 years of age and those from the poorest families were more likely to have an asthma diagnosis in both regions. Black skin color, crowding, and substandard housing were associated with asthma in the South. In the Northeast, children of parents with low schooling were less likely to present asthma. The inequalities were more evident in the South, suggesting variation in asthma determinants across the country.

Perception of Neighborhood Safety and Reported Childhood Lifetime Asthma in the United States (U.S.): A Study Based on a National Survey

BackgroundRecent studies have emphasized the role of psychosocial stressors as a determinant of asthma, and neighborhoods can be a potential source of such stressors. We investigated the association between parental perception of neighborhood safety and reported lifetime asthma among children.Methodology/Principal FindingsData for the study came from the 2003–04 National Survey of Children Health (NSCH); a nationally representative cross-sectional sample of children aged 0–17 years. Demographic, socioeconomic and behavioral covariates were included in the study. Models were estimated after taking account of weighting and complex survey design. Parental report of whether the child has ever been diagnosed with asthma by a physician was used to define the outcome. Parental report of perception of neighborhood safety was the main exposure. In unadjusted models, the odds ratio (OR) for reporting asthma associated with living in neighborhoods that were perceived to be sometimes or never safe was 1.36 (95% confidence intervals [CI] 1.21, 1.53) compared to living in neighborhoods that were perceived to be always safe. Adjusting for covariates including exposure to second hand tobacco smoke, mother's self-rated health, child's physical activity and television viewing attenuated this association (OR 1.25, 95% CI 1.08, 1.43). In adjusted models, the increased odds ratio for reporting asthma was also higher among those who perceived neighborhoods as being usually safe (OR 1.15 95% CI 1.06, 1.26), as compared to always safe, suggestive of a dose-response relationship, with the differentials for usually safe and never safe being statistically significant (p = 0.009).ConclusionPsychosocial stressors may be important risk factors that may impact the pathogenesis of asthma and/or contribute to asthma morbidity by triggering exacerbations through neuroimmunologic mechanisms, as well as social mechanisms.

Control of Persistent Asthma in Spain: Associated Factors

Introduction. The main objective of asthma treatment is tailored control for each patient. However, despite the excellent therapeutic arsenal currently available, many patients remain unable to achieve adequate control of this disease. Objective. The main objective this study was to evaluate the degree of control and the determinants of asthma in patients with persistent asthma in Spain in usual clinical practice. Materials and Methods. This was a cross-sectional epidemiological study. The patients enrolled were 18 years of age or over, with a 6-month history of diagnosed persistent asthma, who were followed up by primary care physicians in Spain between the months of June and December 2006. Demographic and socioeconomic data were collected, as were anthropometric data and different clinical variables. The control of asthma was evaluated using the Asthma Control Questionnaire (ACQ). Results. The study included 6,824 patients, of whom 306 were excluded; therefore the final number of patients analyzed was 6,518 (95.5%). According to severity, 41.4% of patients had mild persistent asthma, 51.2% had moderate persistent asthma, and the remainder severe persistent asthma. The mean score in the ACQ was 1.4 ± 1.0, distributed as follows: in 28.4% of cases, the score was below 0.75; in 31.6%, it was between 0.75 and 1.5; and in 39.7% it was above 1.5. Multiple regression analysis showed that the factor that most affected the degree of control of the disease was classification by severity. Other associated factors were sex, race, body mass index, smoking, level of education, habitual activity, years since diagnosis of asthma, number of exacerbations and admissions to hospital during the last year, and basic treatment of the disease. Conclusions. The number of patients with poorly controlled persistent asthma in Spain is high (71.6%). There are demographic, socioeconomic, anthropometric, and clinical variables that affect the level of control of this disease.

Air pollution as a determinant of asthma among schoolchildren in Mohammedia, Morocco

The objective of the study was to investigate whether air quality in western Morocco is truly a significant risk factor in the development and exacerbation of respiratory diseases and, in particular, asthma. The continuous measurement of the mean concentrations of sulfur dioxide (SO2) in the air and the density of Total Suspended Particulates (TSP) for a period of four years was determined. Information on individual characteristics and indoor environments from 1318 children with an average age of 12 years was evaluated by questionnaire, completed by parents (assisted by professional investigators) and symptoms/diseases were medically diagnosed and reported. We have used the Student's t-test, Chi-square tests & odds ratios (ORs) with 95% confidence intervals (CI 95%) for estimates of the risk of asthma. The prevalence of asthma varies in a significant way according to the zone (χ2 = 14.61, p < 0.05). Respiratory diseases (OR 6.27, 95% confidence interval [CI] 4.09 – 9.64, p < 0.0001), strongly polluted zone (OR 3.62, 95% CI 1.71 – 7.81, p ≤ 0.0001) and infectious diseases (OR 3.29, 95% CI 1.99 – 5.47, p < 0.0001) are high risk factors for asthma. Air pollution is a determinant factor but is not the only factor increasing the risk of asthma in children; other factors such as respiratory diseases, infectious diseases, genetic and passive smoking present a high-risk threat.

Prevalence and determinants of asthma in adult male leather tannery workers in Karachi, Pakistan: A cross sectional study

BackgroundThis study aimed to estimate the prevalence and to identify some risk factors of adult asthma in male leather tannery workers in Karachi, Pakistan.MethodsA cross sectional study was conducted from August 2003 to March 2004 on leather tannery workers of Karachi, Pakistan. Data were collected from 641 workers engaged in 95 different tanneries in Korangi industrial area selected as sample of convenience. Face to face interviews were performed using a structured pre-tested questionnaire by trained data collectors.ResultsPrevalence of adult asthma was 10.8% (69/641) in this study population. The prevalence of perceived work-related asthma was 5.3% (34/641). Multivariable logistic regression model showed that after taking into account the age effect, the leather tannery worker were more likely to be asthmatic, if they were illiterate (adjusted OR = 2.13, 95% CI: 1.17–3.88), of Pathan ethnicity (adjusted OR = 2.69; 95% CI: 1.35–5.36), ever-smoked (adjusted OR = 2.22, 95% CI: 1.16–4.26), reportedly never used gloves during different tanning tasks (OR = 3.28; 95% CI : 1.72–6.26). Also, the final model showed a significant interaction between perceived allergy and duration of work. Those who perceived to have allergy were more likely to have asthma if their duration of work was 8 years (adjusted OR = 2.26; 95% CI: 1.19 – 4.29) and this relationship was even stronger if duration was 13 years (adjusted OR = 3.67; 95% CI: 1.98–6.79).ConclusionPrevalence of asthma in leather tannery workers appears to be high and is associated with educational status, ethnicity, smoking, glove use, perceived to have allergy and duration of work.

Prevalence, severity and determinants of asthma in Danish five‐year‐olds

The prevalence of asthma and wheeze is increasing. To study the annual and cumulative prevalence of asthma and wheeze in 5-y-old Danish children. We obtained data on 3052 (82.0% of eligible) Danish children by a postal parental questionnaire including ISAAC questions regarding respiratory symptoms and our own questions on sociodemography and tobacco exposure. "Wheeze ever" was reported in 38.3%, "doctor-diagnosed asthma ever" in 10.5%, "childhood bronchitis ever" in 30.0%, "current wheeze" (<12 mo) in 19.7%, and being "severe" (>3 episodes) in 3.9% of the children. Current wheeze was associated with male gender (OR 1.63, 95% CI 1.35-1.96), low parental post-primary education (OR 1.29, 95% CI 1.02-1.63 for <3 y vs > or =3 y) and current maternal smoking (OR 1.69, 95% CI 1.39-2.04). "Severe current wheeze" was recognized as asthma in six and childhood bronchitis in three of 10 cases. Nearly all diagnosed asthmatics had suffered wheeze, two-thirds recently. We found a high prevalence of asthma and wheeze in Danish late-preschool children, associated with male gender, current maternal tobacco smoking and low parental post-primary education. The majority of children with current wheeze had an early onset, and severe early symptoms tended to persist. Used with consideration, the label "childhood bronchitis" seems purposeful.

The determination of asthma, rhinitis, eczema, and atopy prevalence in 9- to 11-year-old children in the city of Izmir

The International Study of Asthma and Allergies in Childhood (ISAAC) phase II was designed to allow comparisons between populations in different countries and to investigate possible etiologic factors. This study was conducted to better delineate the prevalence and etiologic factors of asthma, rhinitis, and eczema in Izmir (Turkey) and to be included in the international comparisons by using a standard methodology of ISAAC phase II. The questionnaire was distributed to 2112 students in the 3rd, 4th, and 5th grades of 12 selected primary schools in urban and rural boroughs of Izmir. One thousand two hundred seventeen of these questionnaires were evaluated and physical examinations and skin-prick tests were performed on 1098 of these children. The prevalence values were 15.9% for recent wheezing and 4.8% for physician-diagnosed asthma. The prevalence of sneezing or runny or blocked nose in the past 12 months when the child did not have a cold or flu was 30%. The prevalence of physician-diagnosed allergic rhinitis was 17%. The prevalence of an itchy rash that was coming and going for at least 6 months was 7.2% and the prevalence of physician-diagnosed eczema was 4.9%. Atopic sensitization prevalence in the population was 8.8% with house-dust mite sensitization being the most frequent one. Secretion rales and sibilant wheezing rhoncus were detected in 2.7% of children by chest auscultation. In 1.1% of children flexural dermatitis was detected. Objective tests are necessary for epidemiologic studies of the aforementioned diseases.

Response to Giacaman: Terror toll before Jenin

Having worked in joint Israeli–Palestinian projects in public health going back to the 1980's on lead poisoning,2–5 environmental determinants of asthma in Gaza children6, pesticides, and dioxins,7–8, I have to comment on the context of Giacaman et al 's report on the health, psychological and socio-economic problems of children in Jenin, Tulkarm and Bethlehem following Israel's attacks on these cities in March 2002. This article ignores the decade of deaths, disabling injuries and grief from terror attacks originating mainly from these cities going back to 1994, but ignored …

Asthma and allergic diseases in schoolchildren: third cross‐sectional survey in the same primary school in Ankara, Turkey

We investigated prevalence and determinants of asthma and allergic diseases in a cross-sectional survey of schoolchildren aged 6-14 in 2002. This was the third of a series of cross-sectional surveys, conducted in 1992 and 1997, in the same school in Ankara, Turkey. Questionnaire including information on house characteristics, dietary habits, past and current exposures and diseases were distributed to 1064 children (523 boys, 541 girls) and filled by the parents at home. Percentage of children having a pet was significantly higher (1992: 7.9, 1997: 22.9, 2002: 21), but that of passive smoking was significantly lower (1992: 74, 1997: 64, 2002: 64.1) in 1997 and 2002 when compared with 1992. Current prevalence percentage of asthma (1992: 8.3, 1997: 9.8, 2002: 6.4), wheeze (1992: 11.9, 1997: 13.3, 2002: 6.4), hay fever (1992: 15.4, 1997: 14.1, 2002: 7.2), and eczema (1992: 4, 1997: 4.3, 2002: 1.8) were significantly lower in 2002 compared with 1992. Multiple logistic regression analysis model for current wheeze included ingestion of cow's milk (no regular ingestion: reference, ORs and 95% CIs, <1 glass/day: 0.5, 0.3-1.0; at least 1 glass/day: 0.3, 0.2-0.7), ingestion of red meat (2.2, 1.2-3.8), and currently holding a dog (6.1, 1.6-23.4). Multiple logistic regression analysis model for current hay fever included ingestion of red meat (1.8, 1.1-2.9) and father's education (none of the parents finished secondary school: reference, secondary school to university: 0.5, 0.2-1.0). Our findings suggested that current prevalence of asthma and allergic diseases decreased among schoolchildren in Ankara, in the last 10 yr, and ingestion of milk and red meat could have a role in the occurrence of asthma and hay fever. Detailed assessment of dietary habits is required to test this hypothesis.

Risk of Physician-Diagnosed Asthma in the First 6 Years of Life

The objective of this cohort study was to determine if complications of pregnancy and labor, characteristics at birth, and exposure to infections influence the incidence of asthma in the first 6 years of life. We identified all children born between 1980 and 1990 in the Province of Manitoba, Canada. We used records of physician contacts (inpatient and outpatient) and services of the universal provincial health insurance plan to follow up 170,960 children from birth to the age of 6 years to identify the first diagnosis of asthma. Information on mothers and siblings was also obtained to determine family history of disease and exposure to infections. During the study period, a diagnosis of asthma was made in 14.1% of children by the age of 6 years. The incidence was higher in boys than in girls, in those with family history of allergic diseases. It was higher in urban than in rural areas, and lowest in those born in winter. Asthma was more likely in those with low birth weight and premature birth. Certain congenital abnormalities and complications of pregnancy and labor also increased the risk of asthma. The risk of asthma increased with maternal age. Both upper and lower respiratory infections increased the risk of subsequent asthma, and this effect was more important than exposure to familial respiratory infections, which also tended to increase asthma risk. The risk of asthma decreased with the number of siblings when siblings had a history of allergic disorders. In addition to genetic influences, intrauterine and labor conditions are determinants of asthma. Exposure to both upper and lower respiratory tract infections increases the risk; these infections do not explain the protective effect associated with the increasing number of siblings.

Asthma and allergic rhinitis in Quebec children.

The Health and Social Survey of Quebec Children and Youth, conducted on representative samples of children nine, 13 and 16 years of age, provided data on the prevalence and determinants of asthma and allergic rhinitis in Quebec. To determine the prevalence of asthma and allergic rhinitis among children in the province of Quebec and to identify the determinants of these pathologies. Three groups of more than 1100 children aged nine, 13 and 16 years were recruited. Respiratory symptoms were documented using the International Study of Asthma and Allergies in Childhood questionnaire. Questions enquiring about family income, smoking, degree of urbanization of the child's school's location and various variables related to indoor air were also included. The comparisons of proportions were done using the chi2 test. The prevalence rates for reported history of asthma varied from 14% to 15% depending on the age group. The prevalence of wheezing in the past year was 7% to 8%. Asthma was the primary cause of the limitation of activities due to a health problem in nine- and 13-year-old Quebecers, and the second most common cause in 16-year-old Quebecers. The prevalence of rhinitis, rhinoconjunctivitis and reported history of hay fever increased with age, reaching 28.0%, 15.9% and 21.1%, respectively, in the 16-year-old group. The prevalence of asthma and wheezing was associated with family history and allergies, and inversely related to family income. The prevalence of childhood asthma is high in the province of Quebec. It is a major cause of the limitation of activities due to a health problem for young Quebecers. A family history of asthma and an atopic predisposition are important determinants in the development of asthma in Quebec.

Residential Exposure to Volatile Organic Compounds and Asthma

We critically analysed the literature concerning exposure to volatile organic compounds and asthma. Observational studies have consistently found a relation between volatile organic compounds and indicators of asthma, such as symptoms, peak flows, and objectively measured bronchial reactivity. In contrast, interventional studies have generally failed to find a relation between exposure to residential levels of formaldehyde and other volatile organic compounds and asthma. One hypothesis to explain the discrepancy in findings between interventional and observational studies is that the effect size is small requiring relatively large numbers of study subjects, common in observational studies but often not feasible in interventional studies. Another hypothesis is that longer duration of exposure is important, a common circumstance in observational studies where the home environment is the exposure setting. In contrast, duration of exposure in interventional studies is usually of minutes‐to‐hours in a chamber. Finally, the observed association in observational studies could be confounded by a factor which is a determinant of asthma and is also associated with exposure to volatile organic compounds.

Asthma trends in Switzerland: the Swiss Sentinel Surveillance Network, 1988-1996.

The setting up of the Swiss Sentinel Surveillance Network (SSSN) in 1986 has provided an excellent opportunity to study the distribution and determinants of asthma. The system provides morbidity data, which are representative of family practices in primar