Asthma, airways responsiveness and air pollution in two contrasting districts of northern England

Prevalence of asthma symptoms based on the European Community Respiratory Health Survey questionnaire and FENO in university students: gender differences in symptoms and FENO

BACKGROUND

The fractional concentration of nitric oxide in exhaled air (FENO) is used as a biomarker of eosinophilic airway inflammation. FENO is increased in patients with asthma. The relationship between subjective asthma symptoms and airway inflammation is an important issue. We expected that the subjective asthma symptoms in women might be different from those in men. Therefore, we investigated the gender differences of asthma symptoms and FENO in a survey of asthma prevalence in university students.

METHODS

The information about asthma symptoms was obtained from answers to the European Community Respiratory Health Survey (ECRHS) questionnaire, and FENO was measured by an offline method in 640 students who were informed of this study and consented to participate.

RESULTS

The prevalence of asthma symptoms on the basis of data obtained from 584 students (266 men and 318 women), ranging in age from 18 to 24 years, was analyzed. Wheeze, chest tightness, an attack of shortness of breath, or an attack of cough within the last year was observed in 13.2% of 584 students. When 38.0 ppb was used as the cut-off value of FENO to make the diagnosis of asthma, the sensitivity was 86.8% and the specificity was 74.0%. FENO was ≥ 38.0 ppb in 32.7% of students. FENO was higher in men than in women. The prevalence of asthma symptoms estimated by considering FENO was 7.2%; the prevalence was greater in men (9.4%) than women (5.3%). A FENO ≥ 38.0 ppb was common in students who reported wheeze, but not in students, especially women, who reported cough attacks.

CONCLUSIONS

The prevalence of asthma symptoms in university students age 18 to 24 years in Japan was estimated to be 7.2% on the basis of FENO levels as well as subjective symptoms. Gender differences were observed in both FENO levels and asthma symptoms reflecting the presence of eosinophilic airway inflammation.

TRIAL REGISTRATION NUMBER

UMIN000003244.

Household and environment factors associated with asthma among Indian women: a multilevel approach

BACKGROUND

Asthma is a prevalent disease among adults in India. This study aims to find prevalence and risk factors for asthma among Indian women aged 15 to 49 based on Indian National Family Health Survey-3.

METHODS

Prevalence of asthma was reported per 1,000 women among individual- and household-level variables. Chi-square test was used as test of association. Odds ratio with 95% confidence interval was used to find risk factors. Multilevel logistic regression was used to find risk factors adjusting for the confounding effect. Attributable risk percentage and population-attributable risk percentage were computed and interpreted.

RESULTS

The overall prevalence of asthma was 17 per 1,000 women. Overweight, obesity, exposure to alcohol, smoking, use of biomass for cooking, and low education are proven to be risk factors for asthma. The odds ratio ranges from 1.2 to 3. Not cooking under chimney and exposure to biomass fuels were observed to have high population-attributable risk percentage (19%, 18.6%). Controlling for these variables may reduce major burden of asthma.

CONCLUSION

Modification of household-level variables such as cooking fuel and cooking condition coupled with abstinence in consumption of alcohol and smoking may reduce the prevalence of asthma among women.

Recognition and surveillance of occupational asthma: a preventable illness with missed opportunities

Occupational asthma is common, disabling and costly, and it is often difficult to diagnose. Incidence statistics are consequently unreliable, and there are formidable difficulties in recognizing and managing what should be a preventable illness. The opportunities have largely been missed. The author offers a personal view of what, ideally, should be done--recognizing that at present the ideal is not readily practical. Always consider the possibility of an occupational cause at the time adult-onset asthma is first recognized-the probability of this is of the order 9-15%. Do not prescribe treatment unless this possibility is remote or the asthma is life-threatening. If the possibility is not remote seek immediate advice from a specialized centre, without prescribing masking medication and without curtailing usual work practice. The specialized referral centre should place the accurate measurement of airway responsiveness at the centre of investigatory strategies. A return-to-work study, monitored by serial measurements of airway responsiveness and ventilatory function, provides adequate objective evidence for diagnosis in most cases. When a novel cause is suspected, specific inhalation provocation testing with the particular agent in the specialized centre is desirable. Regular competent surveillance is necessary in high-risk occupational environments; this should include environmental monitoring, the detection of relevant new symptoms, spirometry measurements, serum antibody studies (where available) and a robust protocol for managing inevitable failed attendances.

Long-term effects of ambient air pollution on lung function: a review

Lung function is an important measure of respiratory health and a predictor of cardiorespiratory morbidity and mortality. Over the past 2 decades, more than 50 publications have investigated long-term effects of ambient air pollution on lung function with most finding adverse effects. Several studies have also suggested effects from traffic-related air pollution. There is strong support for air pollution effects on the development of lung function in children and adolescents. It remains unclear whether subjects with slower development of lung function compensate by prolonging the growth phase, or whether they end their development at a lower plateau, thus entering the decline phase with a reduced lung function. In adults, the evidence for long-term air pollution effects is mostly based on cross-sectional comparisons. One recent longitudinal study observed that decreasing pollution attenuated the decline of lung function in adults. Earlier inconclusive cohort studies were based on limited data. There is great diversity in study designs, markers of air pollution, approaches to the measurement of exposure, and choices in lung function measures. These limit the comparability of studies and impede quantitative summaries. New studies should use individual-level exposure assessment to clarify the role of traffic and to preclude potential community-level confounding. Further research is needed on the relevance of specific pollution sources, particularly with regard to susceptible populations and relevant exposure periods throughout life.

Atopy and asthma in rural Poland: a paradigm for the emergence of childhood respiratory allergies in Europe

BACKGROUND

We hypothesized that, in south-west Poland, a 'rural' protective effect on atopy and respiratory allergies would be most pronounced among children but that at all ages would be stronger among those with a rural background.

METHODS

A cross-sectional survey of the inhabitants (age >5 years, n = 1657) of Sobotka, a town of 4000 people in south-west Poland: and seven neighbouring villages. We measured and analysed responses to skin prick tests (atopy) and to a standard questionnaire (asthma and hayfever).

RESULTS

Atopy was very uncommon (7%) among villagers at all ages but not among townspeople (20%, P < 0.001); the differences were most marked among those aged under 40 years. Asthma and hayfever were similarly distributed, both being very rare among villagers. The differences appear to be explained by the cohort effect of a communal move away from rural life. This interpretation is supported by an ecological correlation (rho = -0.59) between rural populations and childhood wheeze in 22 European countries.

CONCLUSION

The very striking differences in the prevalence of allergy between these two neighbouring communities of central Europe reflect the pan-continental population movements that may have been responsible for the emergence of childhood allergies in Europe.

Effects on respiratory health of a reduction in air pollution from vehicle exhaust emissions

AIMS

To determine whether residents of congested streets have a higher prevalence of respiratory symptoms than residents of nearby uncongested streets, and whether their respiratory health improves following a reduction in exposure to traffic related air pollutants.

METHODS

An area was identified where certain streets were subject to air pollution from heavy road traffic, which was likely to improve following the construction of a by-pass. A respiratory survey was conducted among the residents, together with the residents of nearby uncongested streets, at baseline and again a year after the by-pass opened. Measurements were made of air pollutant concentrations in both areas on both occasions.

RESULTS

Initial concentrations of PM10 and PM2.5 were substantially higher in the congested than in the uncongested streets. When the by-pass opened, the volume of heavy goods traffic fell by nearly 50%. PM10 decreased by 23% (8.0 microg/m3) in the congested streets and by 29% (3.4 microg/m3) in the uncongested streets, with similar proportionate falls in PM2.5. There were no clear or consistent differences between the residents of the two areas initially in terms of symptoms or peak flow variability. Repeat questionnaires were obtained from 165 and 283 subjects in the congested and uncongested areas respectively, and showed a tendency for most symptoms to improve in both areas. For chest symptoms, the improvement tended to be greater in the uncongested area, although the difference between the areas was not statistically significant. Rhinitis and rhinoconjunctivitis tended to improve to a greater extent in the congested streets; the difference between the areas was significant for the degree to which rhinitis interfered with daily activities. Peak flow variability tended to improve in the uncongested area.

CONCLUSIONS

The by-pass reduced pollutant levels to a degree that probably alleviates rhinitis and rhinoconjunctivitis but has little effect on lower respiratory symptoms.

Long-term air pollution indicator assessment: example of black smoke in Bordeaux, France

The aim of the second phase of the Pollution Atmosphérique et Affections Respiratoires Chroniques (PAARC) study, started in 1974, was to compare the long-term mortality between populations living in areas with different air pollution levels. In Bordeaux (France), four different areas were concerned by the study. The black smoke measures were realized between 1974 and 1981. After 1981, the stations set specifically for the study were not used any more. The purpose of this study was to estimate the evolution of air pollution in those areas between 1982 and 1997 using the measures of 12 Association de Prévention de la Pollution Atmosphérique (APPA) stations located in Bordeaux city but not in the PAARC areas. The method used was divided in three phases: a correlation study between the stations of the different networks, a selection of the pertinent stations and the setting up of indicators using the arithmetic means method. Monthly means concentrations were estimated from January 1982 to December 1997. Models showed a decrease in black smoke levels whatever the area. The difference in level from one area to another, existing between the areas in 1974, was still with predicted values in 1997, but less important. Black smoke mean concentration for 1982-1997 was, respectively, 16.4 and 16.2 microg/m3, in areas 1 and 2. It was a little bit higher in area 3 with 18.9 microg/m3. Area 4 still has the highest level with 26.3 microg/m3. To conclude, this method enabled to assess different air pollution levels at different times in the four areas of the PAARC study in Bordeaux. Those levels could be used to study the impact of the air pollution on long-term mortality on populations living in the areas considered.

Antenatal determinants of neonatal immune responses to allergens

BACKGROUND

The environmental factors responsible for recent increases in the prevalence of asthma and atopic disease have been assumed to act after birth. Their possible effects on fetal immune development in utero have not been investigated systematically, although sensitization to allergens may occur before birth.

OBJECTIVE

This prospective study determined whether the risk factors for asthma and atopic disease, namely family history of atopic disease, maternal smoking, birth order, or maternal dietary intake of antioxidant vitamins, exert antenatal effects on the fetal immune system that may predispose to childhood atopy.

METHODS

The T helper (Th) cell proliferative responses of cord blood mononuclear cells (CBMC) from a sample of 223 neonates, representative of children born to a cohort of 2000 pregnant women, were measured and related to family, maternal and environmental factors associated with the pregnancy.

RESULTS

The magnitude of CBMC-proliferative responses to allergens increased significantly in association with a family history of atopic disease or maternal smoking, and decreased significantly with increasing birth order and high maternal dietary intake of vitamin E. The epidemiological association between birth order and atopy may therefore be a consequence of antenatal influences rather than of protective effects of childhood infections. The association between maternal intake of vitamin E and CBMC responsiveness suggests that diet during pregnancy may influence the fetal immune system in such a way as to modulate the risk of childhood atopy.

CONCLUSION

These results provide a new insight into the aetiology of atopic disease by demonstrating that the maternal environmental risk factors for atopy, diet, birth order and smoking, influence the development of the fetal immune system. This raises the prospect of preventative public health interventions during pregnancy.

Exhaled NO in asthmatic children in unpolluted and urban environments

BACKGROUND

NO production (NOex) in the airway epithelium is increased in asthmatic patients and is potently inhibited by anti-inflammatory treatments. The study was designed to compare the: (i) levels of NOex in two groups of asthmatic children residing in different environments (one in a national park in the mountains and the other in a large city) and (ii) the influence of glucocorticoids on levels of NOex between the children and those without treatment.

METHODS

The measurements were performed during the same period in the two locations, 100 km apart. NOex was measured using a chemiluminescence analyzer in controls and two comparable groups of asthmatic children. The first group included 63 children (10+/-3 years) recruited from a specialized institution for asthmatic children, and the second group consisted of 46 asthmatic children (9+/-3 years) living in an urban area. A reference group of 17 healthy children residing in the same city was also studied.

MEASUREMENTS AND RESULTS

The concentrations of NOex in children in the specialized institution were significantly lower (P<.001) than those in asthmatic children living in the city (5.1+/-2.4 vs. 13.8+/-9.3 ppb) and comparable to those in healthy controls (5.3+/-4.0 ppb). In the urban area, NOex levels increased when atmospheric pollution recorded on the previous day had increased. In contrast to that observed in the urban children, glucocorticoids had little influence on the levels of NOex in the children living in the specialized institution.

CONCLUSIONS

Although these relationships need to be confirmed, our findings show that for the determination of NOex, specifying the quality of the environment, in particular, the purity of the air respired by asthmatic children, not only at the time of measurement but also over the previous days, is important.

A comparison of the prevalence of respiratory illness and non-specific health symptoms in two Victorian cities

OBJECTIVE

To compare the prevalence of respiratory illness and non-specific health symptoms among adults and children aged 4-15 years living in Portland and Warrnambool, Victoria.

METHODS

A postal survey of 3,903 adults in Portland and Warrnambool systematically selected from the electoral roll was undertaken. Both an adults and children's questionnaire were enclosed in the mailing to each adult. If there were children aged 4-15 years in the household, an adult was asked to complete a questionnaire for the child who would next celebrate a birthday. Questionnaires were returned by 2,111 adults (54%) and for 585 children.

RESULTS

No significant differences in the prevalence of self-reported asthma or wheeze were observed among adults or children residing in Portland and Warrnambool. The likelihood of itchy eyes, skin rash and stuffy nose was significantly higher in Portland adults and children compared with those in Warrnambool. Dry cough at night was increased among Portland children, but not significantly so.

CONCLUSIONS

Higher rates of non-specific symptoms were observed in Portland but from a cross-sectional survey such as this, it is not possible to identify the cause of these higher rates. They may be related to environmental factors such as pollens or emissions from aluminium production, fertiliser production or bulk handling activities on the wharf, or they may be attributable to other factors such as response or recall bias.

Screening older patients for obstructive airways disease in a semi-rural practice

BACKGROUND

Obstructive airways disease in older patients is reported to be not only common, but frequently overlooked and untreated by general practitioners. This study examines the value of screening elderly patients in a large semi-rural general practice for potentially treatable asthma and chronic obstructive pulmonary disease (COPD).

METHODS

A random sample of 353 patients aged 60-75 years attended a nurse run screening clinic for pulmonary function testing, serial peak flow recording, and completion of a symptom questionnaire. Patients with a low forced expiratory volume in one second (below the fifth centile of their predicted value) or >15% mean diurnal variation in peak flow were referred to a doctor's clinic for further diagnostic assessment and/or to discuss possible treatment where appropriate.

RESULTS

Fifty eight patients (16.4%) had obstructive airways disease, the prevalence of asthma being 6.5% and that of COPD 9.9%. Of these, 30 had no previous diagnosis of airways disease and were not on treatment; eight of them had significant airways reversibility and 10 were current smokers. No newly diagnosed patients had severe disease as measured by pulmonary function or quality of life assessment, and six patients accepted treatment.

CONCLUSION

Few older patients benefited from a screening programme for obstructive airways disease in a semi-rural general practice.

The relationship between age and bronchial responsiveness: evidence from a population survey

OBJECTIVES

Increased bronchial responsiveness is a feature of symptomatic asthma, and it predicts the onset of wheezing. We have investigated the relationship between bronchial responsiveness and age in a population sample with an age range of 45 to 86 years.

DESIGN

Cross-sectional population survey.

SETTING

Population of Central Manchester, UK.

PARTICIPANTS

An age-stratified random sample of white adults aged > or = 45 years old and living in Central Manchester. They were recruited from their primary care physician (general practitioner) lists. Patients with confusion and patients who were housebound were excluded.

MEASUREMENTS

Respondents to a mail questionnaire were invited to attend a methacholine bronchial challenge performed using the Newcastle dosimeter method. Respondents with ischemic heart disease or respondents taking oral steroids, beta-blockers, or anticholinergic medication were excluded.

RESULTS

Of the 783 subjects contacted, 92.3% of the subjects responded, and 508 subjects returned enough information for us to deduce their suitability for the bronchial challenge. Of the 395 suitable subjects, 247 subjects participated (62.5% of those invited; 31.5% of the study population), and 208 participants completed the bronchial challenge. Participants were slightly younger than nonparticipants, but they were otherwise representative of the population. Increased bronchial responsiveness (provocative dose of methacholine causing a 20% fall in FEV1 < or = 200 microg) was present in 71 (34.1%) participants. Stepwise multiple regression analysis showed weak, independent, positive associations between bronchial responsiveness and age, and between bronchial responsiveness and the total immunoglobulin E level. There was an independent negative relationship between bronchial responsiveness and the airways caliber (expressed as standardized residuals; R2 = 0.29).

CONCLUSIONS

We have found a high prevalence of increased bronchial responsiveness in this inner-city population of older adults. Bronchial responsiveness showed a weak independent positive association with age.

Prevalence of adult asthma symptoms in relation to climate in New Zealand

We conducted an ecological study linking prevalence of adult asthma symptoms with climate in the 93 New Zealand general electorates. For each electorate, the 12-month period prevalence of self-reported asthma symptoms was determined using a random sample of adults aged 20-44 on the 1991 New Zealand electoral roll. Long-term average climate was estimated using a national climate database and a geographic information system. Asthma prevalence was calculated within quartiles of the exposure variables. Independent effects of climate variables were assessed using linear regression models, with adjustment for confounding by climate, social deprivation, and geographic variables. There was a statistically significant association between asthma prevalence and mean temperature, with the lowest quartile of mean temperature having an approximately 2% lower asthma prevalence. After adjusting for confounding, there was a monotonic increase in asthma prevalence within quartiles of temperature. The results of this study are in agreement with other research suggesting a lower prevalence of asthma at low temperatures. Although on short (day-to-day) time scales, low temperatures may have a direct effect resulting in acute exacerbations of asthma symptoms, warmer average temperatures are associated with increased asthma prevalence. The reasons for this are unclear, although it is possible that on longer term (annual) time scales, higher temperatures are associated with higher levels of allergen exposure.

Individual allergens as risk factors for bronchial responsiveness in young adults

BACKGROUND

Bronchial responsiveness is known to be related to atopy, but the relative contribution of sensitisation to individual allergens in the UK, or whether serum total IgE is an independent risk factor, is unknown.

METHODS

A random sample of 1864 men and women aged 20-44 years, drawn from family health service registers in Cambridge, Ipswich and Norwich, was invited to answer a detailed questionnaire, undergo skin prick tests and methacholine bronchial challenge, and provide a serum sample for measurement of total and specific IgE. The relation of bronchial responsiveness to risk factors was studied in 749 subjects (40.2%) with complete data.

RESULTS

Bronchial responsiveness was increased in those sensitised to cat, D pteronyssinus, Timothy grass and Cladosporium, but decreased in subjects also positive to birch allergen. Additional skin prick tests added little information. Serum total IgE was not significantly related after adjustment for specific IgE to the five allergens. Increasing titres of specific IgE to D pteronyssinus were associated with increasing bronchial responsiveness. Specific IgE to Cladosporium had a prevalence of around 3%, but was associated with greatly increased responsiveness. Decreased baseline lung function was related (p < 0.001) to increased responsiveness. There was an interaction between age and smoking status, with lower responsiveness in older non-smokers.

CONCLUSION

Atopy is the most important risk factor for bronchial responsiveness in this age group, but effects are not additive across all allergens. Research in reducing exposure to house dust mite should also address the role of Cladosporium sensitisation and exposure to indoor moulds.

Risk factors for adult onset wheeze: a case control study

Risk factors associated with adult onset wheeze were examined in a case control study of subjects aged 39-45 yr derived from a community cohort of 2,056 asymptomatic children originally studied in 1964. Participants included 102 cases with adult onset wheeze (since age 15) and 217 controls with no wheeze. Logistic regression analysis was used to determine independent risk factors for wheeze among all cases and three subgroups: doctor diagnosed asthma (n = 24), wheeze with chronic cough and phlegm (n = 31), and other wheeze (n = 47). The risk of adult onset wheeze among all cases increased with low socioeconomic status (relative risk [RR] 2.36), current smoking (RR 2.01), positive atopic status (RR 3.28), and positive family history of atopic disease (RR 5.49). Gender was not related to the risk of wheezing. The pattern of significant independent risk factors differed between the subgroups of cases. Socioeconomic status was associated with cough and phlegm and other wheeze. Smoking habit was only related to cough and phlegm. Atopy was associated with doctor diagnosed asthma and cough and phlegm. Family history of atopic disease was related to all subgroups, suggesting that despite apparent heterogeneity in diagnostic labeling, concurrent symptoms, and other risk factors, the different forms of adult onset wheeze may share a common allergic basis.

Glass bottle workers exposed to low-dose irritant fumes cough but do not wheeze

Workers exposed to irritant fumes experience symptoms both during the acute episode and afterwards. High-dose irritant exposure can result in permanent asthma, but the effects of chronic low-dose irritant exposure are not known. Glass bottle workers are exposed to irritant fumes, and have previously been reported to have an excess of symptoms. We designed a study to compare irritant-exposed glass bottle workers with hospital workers matched for socioeconomic group, area of residence, age, sex, smoking habit, and allergic history. Symptoms reported, spirometry, flow cytometric indices of lymphocyte activation, and past medical and employment histories were compared. We also investigated the prevalence of bronchial hyperresponsiveness to inhaled methacholine and the cough response after inhalation of citric acid and capsaicin. Glass bottle workers showed an excess of upper respiratory tract symptoms, cough, and shortness of breath compared with matched hospital control workers. There was a significant excess of cough induced by citric acid and capsaicin in the bottle workers. However, wheeze, baseline spirometry, flow cytometry, and methacholine challenge were not significantly different between the two groups. These findings suggest that chronic irritant exposure produces an excess of symptoms and increased cough sensitivity but not asthma.