Risk factors for accident and emergency (A&E) attendance for asthma in inner city children.

BACKGROUND: Inner city children make heavy use of accident and emergency (A&E) services for asthma. Developing strategies to reduce this requires a better understanding of the risk factors. METHODS: A case-control study was carried out of children with asthma living in south-east London: 1018 children who attended A&E for asthma over 1 year and 394 children who had not attended A&E for asthma over the previous year. The main risk factors were socioeconomic status, home environment, routine asthma management and parents' psychological responses to and beliefs about the treatment of asthma attacks. RESULTS: A&E attendance was more common in children living in poorer households. No associations were found with home environment or with measures of routine asthma care. Children who had attended outpatients were much more likely to attend A&E (odds ratio (OR) 13.17, 95% CI 7.13 to 24.33). Other risk factors included having a parent who reported feeling alone (OR 2.58, 95% CI 1.71 to 3.87) or panic or fear (OR 2.62. 95% CI 1.75 to 3.93) when the child's asthma was worse; and parental belief that the child would be seen more quickly in A&E than at the GP surgery (OR 2.48, 95% CI 1.62 to 3.79). Parental confidence in the GP's ability to treat asthma attacks reduced the risk of attending A&E (OR 0.30, 95% CI 0.17 to 0.54). CONCLUSIONS: There is no evidence that passive smoking, damp homes or poor routine asthma care explains heavy inner city use of A&E in children with asthma. Reducing A&E use is unlikely to be achieved by improving these, but identifying appropriate settings for treating children with asthma attacks and communicating these effectively may do so.

Cat and dust mite allergen levels, specific IgG and IgG4, and respiratory symptoms in adults.

BACKGROUND: Exposure to allergen may induce a modified T(H)2 response characterized by high IgG(4) levels, absence of IgE sensitization, and a decreased risk of allergic respiratory symptoms. OBJECTIVE: To assess the association of IgG(4) level with allergic respiratory symptoms in a community-based sample of adults. METHODS: Information on exposure to cats, respiratory symptoms, and mattress allergen levels was obtained from 2780 adults. Levels of cat and house dust mite (HDM) specific IgE, IgG, and IgG(4) were measured. The association of exposure to allergen with IgG(4) and of IgG(4) with symptoms was assessed. RESULTS: Geometric mean (GM) cat specific IgG and IgG(4) was higher in subjects who had a cat that was allowed in the bedroom than in subjects without a cat (adjusted ratio of GM IgG(4), 1.41; 95% CI, 1.25-1.57). Levels of HDM specific IgG and IgG(4) were similar in subjects with undetectable and high (>20.22 microg/g) mattress Der 1 levels (adjusted ratio of GM IgG(4), 1.02; 95% CI, 0.89-1.17). There was no evidence that high cat or HDM specific IgG(4) levels were associated with less IgE sensitization or with fewer symptoms. CONCLUSION: In this community-based sample of adults, high IgG(4) levels to cat or HDM were not associated with a lower risk of allergic respiratory symptoms. CLINICAL IMPLICATIONS: In adults, high cat allergen exposure does not protect against respiratory symptoms.

Urban background particulate matter and allergic sensitization in adults of ECRHS II.

BACKGROUND: Epidemiological studies have shown weak or inconsistent associations between ambient air pollutants and allergic sensitization. The aim of this study was to evaluate whether regional urban air pollution may partly explain the large variation in the prevalence of allergic sensitization across cities of the European Community Respiratory Health Survey (ECRHS) II. METHODS: ECRHS is a cross-sectional survey initiated in 29 countries across Europe in the 1990s (ECRHS I) with a follow-up conducted 10 years later (ECRHS II). Subject characteristics were measured by questionnaires and blood tests conducted for the measurement of specific immunoglobulin E. Fine particle mass (PM(2.5), <2.5 microm) and sulphur on PM(2.5) were measured in 21 centres and annual averages of urban regional background air pollution were calculated. Results were scaled by an interquartile range increase in ambient PM(2.5) (6.03 microg/m(3)) and sulphur (1336 ng/m(3)). Generalized estimating equations were applied to compute population average effect estimates with adjustment for age, gender, smoking habit, education and number of siblings. RESULTS: A notable variation in pollution level and prevalence of allergic sensitization was observed. Moreover, exposure to urban regional background air pollution was not associated with allergic sensitization; adjusted odds ratios and 95% confidence interval were 1.02 (0.95-1.09) for PM(2.5) and 1.08 (0.86-1.31) for sulphur. These statistically non-significant associations were sensitive to model specification. CONCLUSIONS: The study suggests that regional air pollution measured at fixed sites is not associated with allergic sensitization among adults in ECRHS II.

Cat allergen level: its determinants and relationship to specific IgE to cat across European centers.

BACKGROUND: Cat allergen level in settled house dust and its determinants in Europe are unknown. OBJECTIVE: The aim of this study is to quantify the level of cat allergens in mattress dust, to study its determinants, and to analyze the relationship with cat specific IgE on community level across European centers. METHODS: Trained field workers collected dust from approximately 3000 mattresses during home visits in 22 European Community Respiratory Health Survey II centers. Sieved dust extracts were assayed for cat allergen using a mAb ELISA assay. RESULTS: The overall geometric mean cat allergen was 0.94 microg/g, ranging from 0.12 microg/g in Huelva, Spain, to 3.76 microg/g in Antwerp, Belgium. Current cat owners' homes showed substantially higher levels than past cat owners' and never cat owners' homes (geometric mean and 95% CI, 61.4 microg/g [48.4-77.9] vs 1.37 microg/g [0.97-1.9] vs 0.29 microg/g [0.27-0.31]). Community prevalence of cat ownership was moderately correlated with cat allergen levels in noncat owners (r(s) = 0.50), but not for past or current cat owners. The multilevel model identified community prevalence of cat keeping as the only statistically significant determinant of mattress cat allergen levels for noncat owners. However, averaged cat allergen levels per center were not related to community prevalence of detectable specific IgE to cat. CONCLUSION: Not having a cat in the home is associated with substantially lower Fel d 1 concentration, but does not protect against high Fel d 1 exposure in communities where cat ownership is common. CLINICAL IMPLICATIONS: People (including patients with cat allergy) who do not own cats may be exposed to high levels of cat allergen in their home, particularly if they live in communities with high levels of cat ownership.

Distribution and determinants of house dust mite allergens in Europe: the European Community Respiratory Health Survey II.

BACKGROUND: Several studies in European homes have described allergen levels from the house dust mite species Dermatophagoides pteronyssinus and to a lesser extent Dermatophagoides farinae, but geographic comparisons of exposure levels and risk factors have been hampered by a lack of standardized methods. OBJECTIVE: To study the distribution and determinants of the major house dust mite allergens Der p 1 and Der f 1 in 10 European countries using a common protocol. METHODS: During home visits with 3580 participants of the European Community Respiratory Health Survey II from 22 study centers, mattress dust was sampled and analyzed for Der p 1, Der f 1, and Der 2 allergen. Information on housing characteristics was obtained by both observations and interview. RESULTS: Der 1 and Der 2 allergens were detectable (>/=0.1 mug/g) in 68% and 53% of the samples, respectively. Large differences in allergen levels between study centers were observed, and geographic patterns for Der p 1 and Der f 1 were different. Low winter temperatures reduced Der p 1 rather than Der f 1. Important risk factors for high allergen levels included an older mattress, a lower floor level of the bedroom, limited ventilation of the bedroom, and dampness for Der p 1 but not for Der f 1. CONCLUSION: There are large qualitative and quantitative differences of house dust mite allergen levels in Europe, which can partly be explained by geographic and housing characteristics. CLINICAL IMPLICATIONS: Mite allergen exposure may be reduced by replacing the mattress regularly and increasing ventilation of the bedroom, particularly in winter.

Change in prevalence of IgE sensitization and mean total IgE with age and cohort.

BACKGROUND: Cross-sectional studies show that the prevalence of IgE sensitization is lower in older age groups than younger age groups. This could reflect either a decrease in sensitization with aging or a higher prevalence of sensitization in more recent birth cohorts. OBJECTIVE: To assess change in IgE sensitization and mean total IgE in young adults as they age. METHODS: Serum specific IgE to common allergens and total IgE were measured on 2 occasions about 9 years apart in 6371 young adults living in 28 centers, mainly in Western Europe, who took part in the European Community Respiratory Health Survey II. Outcomes were analyzed by using generalized estimating equations, and adjustments were made for differences between laboratory measures on the 2 occasions. RESULTS: Overall, there was no net change in the prevalence of sensitization to at least 1 of house dust mite, grass, or cat (net change per 10 years of follow-up, -0.1%; 95% CI, -1.7% to 1.5%), although there was a fall in mean total IgE (ratio of geometric mean total IgE, 0.86; 95% CI, 0.79 to 0.93). There was evidence that sensitization to at least 1 allergen was higher in more recent cohorts, and this was largely explained by a higher prevalence of sensitization to grass. CONCLUSION: The disease burden associated with IgE sensitization in adults, and particularly with IgE sensitization to grass, is likely to continue to increase for some time despite current evidence that the increase in allergy seen in children may have ceased.

An increase in bronchial responsiveness is associated with continuing or restarting smoking.

RATIONALE: Bronchial responsiveness (BHR) has been found to be associated with smoking, atopy, and lower lung function in cross-sectional studies, but there is little information on determinants of change in adults. OBJECTIVES: To analyze change in bronchial responsiveness in an international longitudinal community study. METHODS: The study was performed in 3,993 participants in the European Community Respiratory Health Survey who had bronchial responsiveness measured in 1991-1993, when aged 20 to 44 yr, and in 1998-2002. MEASUREMENTS: Bronchial responsiveness was assessed by methacholine challenge. Serum samples were tested for total IgE, and for specific IgE to four common allergens. Smoking information was obtained from detailed administered questionnaires. Change in bronchial responsiveness was analyzed by change in IgE sensitization, smoking, and lung function, with tests of interaction terms with age and sex. MAIN RESULTS: Continuing and restarting smokers had increasing bronchial responsiveness, approximately equivalent to a mean reduction in PD20 of 0.68 and 0.75 doubling doses, respectively, over 10 yr, in addition to a small increase explained by decline in FEV1. No other risk factor for change in bronchial responsiveness was identified. CONCLUSIONS: Smoking is a risk factor for increasing bronchial responsiveness over and above the effect of decreasing lung function. Neither baseline IgE sensitization nor change in sensitization was shown to be a risk factor for increasing BHR, the latter possibly due to little overall increase or decrease in sensitization.

Smoking cessation, lung function, and weight gain: a follow-up study.

BACKGROUND: Only one population-based study in one country has reported effects of smoking cessation and weight change on lung function, and none has reported the net effect. We estimated the net benefit of smoking cessation, and the independent effects of smoking and weight change on change in ventilatory lung function in the international European Community Respiratory Health Survey. METHODS: 6654 participants in 27 centres had lung function measured in 1991-93, when aged 20-44 years, and in 1998-2002. Smoking information was obtained from detailed questionnaires. Changes in lung function were analysed by change in smoking and weight, adjusted for age and height, in men and women separately and together with interaction terms. FINDINGS: Compared with those who had never smoked, decline in FEV1 was lower in male sustained quitters (mean difference 5.4 mL per year, 95% CI 1.7 to 9.1) and those who quit between surveys (2.5 mL, -1.9 to 7.0), and greater in smokers (-4.8 mL, -7.9 to -1.6). In women, estimates were 1.3 mL per year (-1.5 to 4.1), 2.8 mL (-0.8 to 6.3) and -5.1 mL (-7.5 to -2.8), respectively. These sex differences were not significant. FEV1 changed by -11.5 mL (-13.3 to -9.6) per kg weight gained in men, and by -3.7 mL per kg (-5.0 to -2.5) in women, which diminished the benefit of quitting by 38% in men, and by 17% in women. INTERPRETATION: Smoking cessation is beneficial for lung function, but maximum benefit needs control of weight gain, especially in men.

Geographic variations in the effect of atopy on asthma in the European Community Respiratory Health Study.

BACKGROUND: Atopy has long been related to asthma. The prevalences of both atopy and asthma have shown substantial variation. OBJECTIVE: We sought to assess geographic variations in the fraction of asthma attributable to IgE sensitization to specific allergens in the European Community Respiratory Health Survey. METHODS: A cross-sectional study was undertaken during the years 1991 and 1992 on 13,558 individuals in 36 centers in 16 countries. Asthma was defined in several ways, variously incorporating reported symptoms, bronchial responsiveness to methacholine, and physician diagnosis. Specific IgE against house dust mite (Dermatophagoides pteronyssinus), cat, timothy grass, Cladosporium herbarum , and a local allergen (birch, Parietaria judaica , or ragweed) were measured. RESULTS: The overall attributable fraction (AF) of asthma symptoms caused by atopy was 30% but varied widely between centers, ranging from 4% to 61%. The overall AF increased to 43% when asthma was based on wheezing and bronchial responsiveness, to 45% with a physician diagnosis of asthma, and to 48% when the patient reported more than 12 attacks in the last year. Between centers, the AF for atopy was significantly correlated with the prevalence of atopy among the asthmatic patients ( r = 0.91) and with the sensitization to house dust mite ( r = 0.64), as well as with the prevalence of asthma among atopic individuals ( r = 0.43) and the prevalence of asthma among nonatopic individuals ( r = -0.51). CONCLUSION: The effect of atopy on the prevalence of asthma varies widely between centers, probably because of variations in factors related to the expression of asthma and to the prevalence of sensitization, particularly to house dust mite.

PM2.5 assessment in 21 European study centers of ECRHS II: Method and first winter results.

The follow-up of a cohort of adults from 29 European centers of the former European Community Respiratory Health Survey (ECRHS) I (1989-1992) will examine the long-term effects of exposure to ambient air pollution on the incidence, course, and prognosis of respiratory diseases, in particular asthma and decline in lung function. The purpose of this article is to describe the methodology and the European-wide quality control program for the collection of particles with 50% cut-off size of 2.5 microm aerodynamic diameter (PM2.5) in the ECRHS II and to present the PM2.5 results from the winter period 2000-2001. Because PM2.5 is not routinely monitored in Europe, we measured PM2.5 mass concentrations in 21 participating centers to estimate background exposure in these cities. A standardized protocol was developed using identical equipment in each center (U.S. Environmental Protection Agency Well Impactor Ninety-Six [WINS] and PQ167 from BGI, Inc.). Filters were weighed in a single central laboratory. Sampling was conducted for 7 days per month for a year. Winter mean PM2.5 mass concentrations (November 2000-February 2001) varied substantially, with Iceland reporting the lowest value (5 microg/m3) and northern Italy the highest (69 microg/m3). A standardized procedure appropriate for PM2.5 exposure assessment in a multicenter study was developed. We expect ECRHS II to have sufficient variation in exposure to assess long-term effects of air pollution in this cohort. Any bias caused by variation in the characteristics of the chosen monitoring location (e.g., proximity to traffic sources) will be addressed in later analyses. Given the homogenous spatial distribution of PM2.5, however, concentrations measured near traffic are not expected to differ substantially from those measured at urban background sites.

Housing characteristics, reported mold exposure, and asthma in the European Community Respiratory Health Survey.

BACKGROUND: The effects of home dampness and mold exposure on adult asthma are not clear. OBJECTIVE: We aimed to investigate the associations between housing characteristics related to dampness, mold exposure, and house dust mite levels and adult asthma in 38 study centers from the European Community Respiratory Health Survey. METHODS: Data about the present home, heating and ventilation systems, double glazing, floor covers, recent water damage, and mold exposure were obtained by means of an interviewer-led questionnaire. The associations between these factors and asthma, as defined on the basis of symptoms in the last year, and of bronchial responsiveness, as determined with methacholine challenge, were evaluated. Odds ratios (ORs) were obtained by using random-effects meta-analyses adjusted within study centers for sex, age group, and smoking status. RESULTS: Fitted carpets and rugs in the bedroom were related to fewer asthma symptoms and bronchial responsiveness (OR range, 0.69-0.91). This effect was consistent across centers and more pronounced among house dust mite-sensitized individuals. Reported mold exposure in the last year was associated with asthma symptoms and bronchial responsiveness (OR range, 1.14-1.44). This effect was homogeneous among centers and stronger in subjects sensitized to Cladosporium species. In centers with a higher prevalence of asthma, the prevalence of reported indoor mold exposure was also high. This association was observed for reported mold exposure by asthmatic subjects (Spearman r (s) = 0.46), as well as reported mold exposure by nonasthmatic subjects (r (s) = 0.54). Reported mold exposure was highest in older houses with recent water damage. CONCLUSION: We conclude that indoor mold growth has an adverse effect on adult asthma.