Longitudinal change of prebronchodilator spirometric obstruction and health outcomes: results from the SAPALDIA cohort.

BACKGROUND: Understanding the prognostic meaning of early stages of chronic obstructive pulmonary disease (COPD) in the general population is relevant for discussions about underdiagnosis. To date, COPD prevalence and incidence have often been estimated using prebrochodilation spirometry instead of postbronchodilation spirometry. In the SAPALDIA (Swiss Study on Air Pollution and Lung Disease in Adults) cohort, time course, clinical relevance and determinants of severity stages of obstruction were investigated using prebronchodilator spirometry. METHODS: Incident obstruction was defined as an FEV(1)/FVC (forced expiratory volume in 1 s/forced vital capacity) ratio >or=0.70 at baseline and <0.70 at follow-up, and non-persistence was defined inversely. Determinants were assessed in 5490 adults with spirometry and respiratory symptom data in 1991 and 2002 using Poisson regression controlling for self-declared asthma and wheezing. Change in obstruction severity (defined analogously to the GOLD (Global Initiative for Chronic Obstructive Lung Disease) classification) over 11 years was related to shortness of breath and health service utilisation for respiratory problems by logistic models. RESULTS: The incidence rate of obstruction was 14.2 cases/1000 person years. 20.9% of obstructive cases (n = 113/540) were non-persistent. Age, smoking, chronic bronchitis and non-current asthma were determinants of incidence. After adjustment for asthma, only progressive stage I or persistent stage II obstruction was associated with shortness of breath (OR 1.71, 95% CI 0.83 to 3.54; OR 3.11, 95% CI 1.50 to 6.42, respectively) and health service utilisation for respiratory problems (OR 2.49, 95% CI 1.02 to 6.10; OR 4.17 95% CI 1.91 to 9.13, respectively) at follow-up. CONCLUSIONS: The observed non-persistence of obstruction suggests that prebronchodilation spirometry, as used in epidemiological studies, might misclassify COPD. Future epidemiological studies should consider both prebronchodilation and postbronchodilation measurements and take specific clinical factors related to asthma and COPD into consideration for estimation of disease burden and prediction of health outcomes.

Reference equations for lung function screening of healthy never-smoking adults aged 18-80 years.

The need for updated spirometric reference values to be used on European populations is widely acknowledged, especially for subjects aged >70 yrs. Their reference values are generally based on extrapolations. The aim of the present study was to calculate reference values for lung function screening of healthy, never-smoking adults aged 18-80 yrs and to compare them with the most widely used reference equations. Results of screening spirometry of 8,684 healthy, never-smoking adults were used to calculate mean values and fifth percentiles of lung function variables. The European Community of Coal and Steel (ECCS) reference equations underestimate forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC). For example, in 50-yr-old males (height 175 cm), lower limits of normal for FEV(1) are underestimated by 198 mL, and for FVC by 210 mL. In 50-yr-old females (height 165 cm), lower limits of normal for FEV(1) are underestimated by 191 mL, and for FVC by 270 mL. The decline of FVC in elderly subjects is steeper than predicted by the ECCS. Reference equations derived from spirometry data locally collected in a practical setting by well-trained personnel might be more appropriate for everyday use than generally used equations based on data from scientific studies in the distant past.

Ultrafine particle emissions from waterpipes.

OBJECTIVES: Ultrafine particle emissions from waterpipes and their impact on human health have not been extensively studied. The aim of this study was to characterise the inhalation pattern of waterpipe smokers, and (a) construct apparatus to simulate waterpipe smoking in the laboratory, and (b) characterise mainstream emissions from waterpipes under different smoking conditions. METHODS: Real life waterpipe smoking patterns were first measured with a spirometer. The average smoking pattern was then mechanically simulated in apparatus. Total particle number concentrations were determined with a condensation particle counter (CPC) for particles between 0.02 microm and 1 microm (P-Trak UPC, Model 8525, TSI) and the particle size fraction was determined with a differential mobility analyser (DMA) for particles from 0.01 microm to 0.5 microm. This instrument was coupled with a laser particle spectrometer for particles between 0.35 microm and 10 microm (Wide Range Particle Spectrometer, Model 1000XP, MSC Corp). Carbon monoxide levels were determined with an electrochemical sensor (Q-Trak monitor, Model 8554, TSI). RESULTS: The tidal volume of an average waterpipe breath of 5 seconds was found to be 1 (SD 0.47) litre. The intervals between breaths on average were 25.5 (SD 10.2) seconds. Particle number concentrations of ultrafine particles in mainstream smoke during waterpipe smoking ranged up to 70 x 10(9) particles per litre. The median diameter of the particles in a full smoking set with charcoal, tobacco and water was 0.04 microm. Smoke from the heated tobacco contributed to particles in the size range between 0.01 microm and 0.2 microm. The glowing piece of charcoal only contributed to particles smaller than 0.05 microm. CONCLUSIONS: Waterpipe smoking emits large amounts of ultrafine particles. With regard to particle emissions, smoking waterpipes may carry similar health risks to smoking cigarettes.

Smoke-free cafe in an unregulated European city: highly welcomed and economically successful.

OBJECTIVE: In a unique setting with two identical cafes, which only differed in their smoking ordinances, this study assessed the influence of smoking policies on the choice of the cafe, investigated regulatory preferences among customers, and evaluated the claim that smoking cafes have better sales performance in a city without smoking bans. METHODS: In a parallel assessment, customers of both cafes answered a questionnaire. Sales were compared and air pollutants were measured to confirm air quality differences. RESULTS: The two customer groups (n = 177) differed only with regard to smoking status (p < 0.01). The smoking regulation was the most often cited selection criterion (83%). In the non-smoking café, 89% indicated that they were usually annoyed by smoke in coffee houses, and 62% would avoid or leave cafes for this reason. Two thirds stated that all cafe/restaurants should offer the opportunity of a smoke-free environment. However, almost half stated that mandatory regulations are not needed and that customers should make individual arrangements based on tolerance and courtesy. Those who were informed about the health effects of secondhand smoke were more likely to call for clear policies. Whereas sales showed no differences, tips were 22% (p < 0.001) higher in the non-smoking cafe. CONCLUSION: In a generation raised in smoking friendly environments, customers paradoxically ask for a landmark shift towards smoke-free opportunities, while substantially adhering to the tobacco industry paradigm of promoting "tolerance" rather than smoke-free policies. Given the clear preference of a large number of customers, hospitality businesses could, however, greatly profit from offering smoke-free environments even in the absence of regulatory policies.

[Pulmonary rehabilitation of COPD in Switzerland--an assessment of current status]. / Pulmonale Rehabilitation bei COPD in der Schweiz--eine Standortbestimmung.

The aim of this survey was to characterize respiratory rehabilitation programmes for patients with COPD in Switzerland. Rate of return of questionnaires was 94%. In 2001, 2238 patients with COPD followed an inpatient (1790) or outpatient (448) respiratory rehabilitation programme. This corresponds to 1% of all patients with COPD in Switzerland. Physical exercise is estimated to be significantly more important compared to breathing exercises, patient education and psychosocial support although this prioritization is not as pronounced as in the current literature. Disease-specific instruments to measure health related quality of life that represents the most important outcome measure for patients with COPD should be implemented in practice. Thereby both the components of rehabilitation programmes and predictive factors for a successful rehabilitation could be evaluated.

[Overweight and obesity in the Zurich canton. A LuftiBus study]. / Ubergewicht und Adipositas im Kanton Zürich. Eine LuftiBus Studie.

In this study the data from 30,598 subjects participating in the LuftiBus project during 1993-1998 were analyzed for the prevalence rates of overweight and obesity. 36.6% of men and 23.6% of the women in the total population were overweight (BMI 25.0-29.9 kg/m2) and 6.6% of the men as well as 7.5% of the women were obese (BMI > 30.0 kg/m2). At a younger age the women were in general lighter, however, with advancing age women became heavier than men. The prevalence data from this study are in quite good agreement with data from other Swiss epidemiologic studies as well international studies. The rather high prevalence rates of obesity show clearly that the problem of obesity can only be solved by preventive means.

Occupational exposure to inhalative irritants and methacholine responsiveness.

OBJECTIVES: Occupational exposures to inhalative irritants have been associated with an increased reporting of respiratory symptoms in previous studies. Methacholine responsiveness represents a continuous measure of airway responsiveness. As such, it may be less subject to recall bias and more sensitive to detecting effects of occupational exposure on airways. Such effects may be stronger among atopic persons. The objective of the study was to examine the relationship between self-reports of occupational exposure to dusts, gases, vapors, aerosols, and fumes and methacholine responsiveness. METHODS: A sample was studied of never smokers (N=3044) chosen randomly from 8 areas in Switzerland. Atopy was defined as any positive skin test to 8 inhalative allergens. Nonspecific bronchial reactivity was tested using methacholine chloride and quantified by calculating the slope of the dose-response. RESULTS: The methacholine slopes were 19% [95% confidence interval (95% CI) 6-32] higher for never smokers with exposure to dusts, fumes, vapors, gases, or aerosols than for the unexposed group. When only atopic never smokers were examined. the increase was larger (37%, 95% CI 7-75), and for persons with >2 positive skin prick tests the effect was still higher (42%, 95% CI -1.5-104). Exposure to vapors and aerosols was strongly associated with increased methacholine slopes among the atopic subjects. CONCLUSIONS: Occupational exposure, particularly to dusts and fumes, was associated with increased bronchial reactivity in never smokers in this study. The magnitude of the effect was larger among atopic subjects.

Clinically "small" effects of air pollution on FVC have a large public health impact. Swiss Study on Air Pollution and Lung Disease in Adults (SAPALDIA) - team.

Epidemiological studies have repeatedly established adverse health effects due to long-term exposure to ambient air pollution. The Swiss Study on Air Pollution and Lung Disease in Adults (SAPALDIA) published a -3.14% decrease in forced vital capacity (FVC) per 10 microg x m(-3) increment in particulate matter (particles with a 50% cut-off aerodynamic diameter of 10 microm (PM(10)). Compared to the within-subject variability of FVC, the effect may be considered small. This individual (or clinical) perspective is, however, misleading. The purpose of this study was to demonstrate the public health relevance of apparently "small" effects, using the impact of PM10 on FVC as an example. The scenario compares a population A, exposed to an annual mean PM10 of 20 microg x m(-3), with a population B exposed to 30 microg x m(-3) mean PM10. A shift of -3.14% in the population distribution of FVC increases the number of subjects in the lower tail of the distribution. In population B a relative increase was expected of 47% (16-91%) in the prevalence of "FVC <80% predicted", (i.e., from 5.17 to 7.59% and 5.88 to 8.65% among males and females, respectively). The relative increase in the prevalence of "FVC <70% predicted" (approximately 1% of population) was 63% (30-98%, males) and 57% (21-86%, females). An epidemiological estimate of a change in the mean value of the population distribution should not be misinterpreted as an effect on the individual level. However, the impact of a 10 microg x m(-3) increase in particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) on the number of subjects with a clinically relevant reduction in lung function is quantitatively important.

[Inpatient rehabilitation in inpatients with chronic obstructive lung diseases (COPD): effect on physical capacity for work, psychological wellbeing and quality of life]. / Stationäre Rehabilitation bei Patienten mit chronisch obstruktiver Lungenkrankheit (COLK): Effekte auf körperliche Leistungsfähigkeit, psychisches Wohlbefinden und Lebensqualität.

Success of inpatient rehabilitation for patients with chronic obstructive pulmonary disease (COPD) was assessed in a prospective study of 39 patients (mean age = 71 years). Six months after hospital stay (mean duration 22.4 days), physical endurance as assessed by the 6-minute walk distance remained unchanged. Subjective health measures improved (SF36 21 vs 29%; p < 0.05), MRC-dyspnoea was reduced (2.61 vs 2.19; p < 0.05) and measures of global quality of life also improved (56.1 vs 67.5; p < 0.05). Meanwhile, anxiety symptoms were reduced (7.7 vs 6.0; p < 0.05); no changes in depression scores were observed (6.8 vs 6.2; p = 0.271). A novel visual method to assess the burden of suffering, PRISM (Pictorial Representation of Illness and Self Measure), was applied for the first time in COPD patients. PRISM scores improved significantly (6.3 vs 12.2; p < 0.001). In conclusion, inpatient pulmonary rehabilitation improved subjective physical health measures and reduced anxiety levels.

Peak flow variability in the SAPALDIA study and its validity in screening for asthma-related conditions. The SPALDIA Team.

We used 3-wk peak expiratory flow (PEF) measurements (twice daily) made in the diary study of the population-based Swiss Study on Air Pollution and Lung Disease in Adults to describe PEF-variability (PEF(var)) (amplitude as a percent of the mean, PEF [i.e., difference between morning and evening values divided by the mean]) in the study population and in five subgroups (physician-diagnosed asthma; current asthma, or physician-diagnosed asthma plus asthma attacks and/or medication; history of wheezing without a cold; hyperreactive; and nonsymptomatic). We assessed the performance of PEF(var) as a potential tool with which to screen for asthma. Alternatively, subjects with a PEF(var) of >/= 20%, >/= 30%, and >/= 50% on at least 2 d were considered to have high variability. The analyses were conducted for subgroups with different pretest probabilities for asthma-related conditions. The median PEF(var) was 4.5%. Among asthmatic subjects, women had nonsignificantly higher PEF(var) values than did men. In all other groups, women had significantly lower PEF(var). Both in the entire population and in subgroups with a higher pretest probability for asthma-related conditions, screening performance of PEF was limited. A PEF(var) of >/= 20% on at least 2 d detected current asthma with a sensitivity of 36% (specificity = 90%; positive predictive value = 16.4%). Results were better among subjects with a history of wheezing without colds (sensitivity = 40.4%; specificity = 83.6%; positive predictive value = 45.2%). PEF(var), a useful measure both clinically and in epidemiology, is of limited value when unselected populations are screened for asthma-related conditions, since the overlap of PEF(var) distributions across subgroups is large.

Long-term ambient air pollution and respiratory symptoms in adults (SAPALDIA study). The SAPALDIA Team.

The association between long-term exposure to ambient air pollution and respiratory symptoms was investigated in a cross-sectional study in random population samples of adults (aged 18 to 60 yr, n = 9,651) at eight study sites in Switzerland. Information on respiratory symptoms was obtained with an extended version of the European Community Respiratory Health Survey questionnaire. The impact of annual mean concentrations of air pollutants was analyzed separately for never-, former, and current smokers. After controlling for age, body mass index, gender, parental asthma, parental atopy, low education, and foreign citizenship, we found positive associations between annual mean concentrations of NO2, total suspended particulates, and particulates of less than 10 micrometers in aerodynamic diameter (PM10) and reported prevalences of chronic phlegm production, chronic cough or phlegm production, breathlessness at rest during the day, breathlessness during the day or at night, and dyspnea on exertion. We found no associations with wheezing without cold, current asthma, chest tightness, or chronic cough. Among never-smokers, the odds ratio (95% confidence interval) for a 10 micrograms/ m3 increase in the annual mean concentration of PM10 was 1. 35 (1.11 to 1.65) for chronic phlegm production, 1.27 (1.08 to 1.50) for chronic cough or phlegm production, 1.48 (1.23 to 1.78) for breathlessness during the day, 1.33 (1.14 to 1.55) for breathlessness during the day or at night, and 1.32 (1.18 to 1.46) for dyspnea on exertion. No associations were found with annual mean concentrations of O3. Similar associations were also found for former and current smokers, except for chronic phlegm production. The observed associations remained stable when further control was applied for environmental tobacco smoke exposure, past and current occupational exposures, atopy, and early childhood respiratory infections when restricting the analysis to long-term residents and to non- alpine areas, and when excluding subjects with physician-diagnosed asthma. The high correlation between the pollutants makes it difficult to sort out the effect of one single pollutant. This study provides further evidence that long-term exposure to air pollution of rather low levels is associated with higher prevalences of respiratory symptoms in adults.

Current allergic asthma and rhinitis: diagnostic efficiency of three commonly used atopic markers (IgE, skin prick tests, and Phadiatop). Results from 8329 randomized adults from the SAPALDIA Study. Swiss Study on Air Pollution and Lung Diseases in Adults.

Total serum IgE, Phadiatop, and the skin prick test (SPT) are commonly used to diagnose atopic diseases. However, no large study has ever been done to test their diagnostic efficiency. We studied the diagnostic value of these three atopic markers in 8329 well-randomized adults from the Swiss Population Registry. The prevalence of current allergic asthma (CAA) was 1.8% and of current allergic rhinitis (CAR) 16.3%. The prevalences of positive Phadiatop, positive SPT (at least, one out of eight SPT to common aeroallergens with a wheal of > or = 3 mm), and positive total IgE (IgE > or = 100 kU/l) were 29, 23, and 23%, respectively. To diagnose CAA and CAR, the sensitivity of Phadiatop was significantly higher than that of SPT (72.5% vs 65.4%, 77.1% vs 68.4% respectively; P < 0.01 and < 0.001) and IgE (72.5% vs 56.9%, 77.1% vs 43.9%, respectively; both P < 0.001). The sensitivity of SPT was significantly higher (68.4% vs 43.9% P < 0.001) than that of IgE to diagnose CAR. When CAA and CAR were excluded, the SPT specificity was significantly higher than that of Phadiatop (77.8% vs 71.9% and 85.9% vs 80.5%, respectively; both P < 0.001): when CAR was excluded, SPT was significantly higher than IgE (85.9 vs 81.4%; P < 0.001). SPT had significantly the best positive predictive value for CAA (5.2% for SPT vs 4.6% for both IgE and Phadiatop; both P < 0.001) and CAR (48.7% for SPT vs 43.5% for Phadiatop and 31.6% for IgE; both P < 0.001). The three markers of atopy had roughly the same negative predictive value (NPV) for CAA, but IgE had a significantly lower NPV for CAR than SPT and Phadiatop (88.1% vs 93.3% and 94.7%, respectively; both P < 0.001). The diagnostic efficiency of SPT was significantly higher than that of Phadiatop (83.1% vs 79.9% and 77.6 vs 71.9%, respectively; both P < 0.001) to diagnose CAR and CAA. IgE and SPT had equal efficiency (77.6%), which was significantly higher than that of Phadiatop, to diagnose CAA (71.9%; both P < 0.001). In conclusion, SPT have the best positive predictive value and the best efficiency to diagnose respiratory atopic diseases. Furthermore, SPT give information on sensitivity to individual allergens and should therefore be used primarily by clinicians to assess respiratory allergic diseases. Moreover, they are cheaper and provide immediate, educational information for both patient and physician.

Associations between lung function and estimated average exposure to NO2 in eight areas of Switzerland. The SAPALDIA Team. Swiss Study of Air Pollution and Lung Diseases in Adults.

In this paper, we present results from the SAPALDIA study (Swiss Study on Air Pollution and Lung Diseases in Adults) regarding associations between lung function [forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1)], as assessed during the cross-sectional study in 1991, and average levels of NO2 exposure within the eight study communities. We distinguished average home outdoor exposure and average personal exposure to NO2 and obtained exposure estimates by computing regional averages of passive sampler measurements performed by a random subsample of SAPALDIA participants in 1993. Previous analyses had revealed associations between average lung function and average air pollution levels between communities. The present results show that such associations may also be seen within communities: a 10-micrograms per m3 increase in average home outdoor and personal exposure to NO2 between zones of residence of the same community was associated with a change in average FVC by -0.59% [95% confidence limits (CL) = 0.01, -1.19] and -0.74% (95% CL = -0.07, -1.41), respectively. These values, however, are smaller than the ones found for the corresponding associations between study communities: -1.67% (95% CL = -1.01, -2.33) and -2.93% (95% CL = -2.11, -3.75), respectively. The different magnitudes of these two types of associations might be explained by differences in spatial variation between various components of air pollution.

Transmission of tuberculosis in the metropolitan area of Zurich: a 3 year survey based on DNA fingerprinting.

Between 1991 and 1993, 444 inhabitants of the metropolitan area of Zurich were reported as confirmed or suspected cases of tuberculosis (TB). Overall, isolates of Mycobacterium tuberculosis of 361 patients (90% of the bacteriologically confirmed cases) were available to study the frequency of transmission of the strains on a molecular level. Restriction fragment length polymorphism (RFLP) analysis was performed by using IS6110 and the polymorphic GC-rich sequence (PGRS) as genetic markers. Ninety nine isolates shared by 77 patients (21.3%) were associated with 28 IS6110-defined clusters. However, secondary typing of low copy number isolates decreased the number of clusters to 25, encompassing 81 isolates from 63 (17.5%) patients. By deoxyribonucleic acid (DNA) fingerprinting plus conventional contact tracing, definite transmission of TB was proven in only five patients (1.4%) and assumed in 20 patients (5.6%). In all other cluster-associated isolates, no epidemiological connections between the patients could be found using the clinical and sociodemographic data available. The present study demonstrates that in the time period studied only minor transmission occurred.

Personal exposure to nitrogen dioxide in Switzerland. SAPALDIA team. Swiss Study on Air Pollution and Lung Diseases in Adults.

Home indoor and outdoor levels, and personal exposures to NO2 were determined for more than 500 subjects in a subpopulation of SAPALDIA by using passive samplers. The overall personal NO2 average was found to be 27 micrograms m-3, the overall indoor average 21 micrograms m-3 and the overall outdoor average 31 micrograms m-3. Personal NO2 levels ranged between the outdoor and indoor levels, with the exception of study areas with low NO2 concentrations. In the winter, the indoor/outdoor ratios were lower than in the summer. Outdoor NO2 levels were higher in winter. In some study areas, indoor NO2 levels were lower in the winter than in the summer due to reduced ventilation but this was not consistent. Personal NO2 concentrations were very similar during all seasons. Gas-cooking and smoking were important factors for elevated indoor and personal NO2 levels (contribution: 5 micrograms m-3, 2 micrograms m-3, respectively). Personal exposure to NO2 correlated best with the indoor NO2 concentrations.