Characteristics of nonsmoking women exposed to spouses who smoke: epidemiologic study on environment and health in women from four Italian areas.

The aim of this study was to evaluate whether risk factors associated with cardiovascular or respiratory diseases and lung cancer occur differently among nonsmoking women in Italy with and without exposure to environmental tobacco smoke (ETS) from husbands that smoke. We performed a cross-sectional study of 1,938 nonsmoking women in four areas of Italy. Data on respiratory and cardiovascular risk factors and on diet were collected using self-administered questionnaires. Medical examinations and blood tests were administered; urine cotinine levels were measured. Nonsmoking women ever exposed to husbands' smoking were compared with unexposed women for several factors: education, husband's education, household crowding, number of children, current or past occupation, exposure to toxic substances at work, parental diseases, self-perceived health status, physician-diagnosed hypertension, hypercholesterol, diabetes, osteoporosis, chronic respiratory diseases, blood pressure medications, lifestyle and preventive behaviors, dietary variables, systolic and diastolic blood pressure, body mass index, waist-hip ratio, triceps skin folds, plasma antioxidant (pro-) vitamins (- and ss-carotene, retinol, l-ascorbic acid, -tocopherol, lycopene), serum total and HDL cholesterol, and triglycerides. Women married to smokers were more likely to be less educated, to be married to a less educated husband, and to live in more crowded dwellings than women married to nonsmokers. Women married to smokers were significantly less likely to eat cooked [odds ratio (OR) = 0.72; 95% confidence interval (CI), 0.55-0.93] or fresh vegetables (OR = 0.63; CI, 0.49-0.82) more than once a day than women not exposed to ETS. Exposed women had significantly higher urinary cotinine than unexposed subjects (difference: 2.94 ng/mg creatinine). All the other variables were not more prevalent among exposed compared to unexposed subjects. The results regarding demographic factors are easily explained by the social class distribution of smoking in Italy. A lower intake of vegetables among exposed women in our study is consistent with the available literature. Overall, our results do not support previous claims of more frequent risk factors for cardiovascular and pulmonary diseases among ETS-exposed subjects. In Italy, as elsewhere in Europe and North America, women who have never smoked but are married to smokers are likely to be of lower social class than those married to never-smokers. However, once socioeconomic differences are considered, the possibility of confounding in studies on the health effects of ETS is minimal.

Prevalence of airways obstruction in a general population: European Respiratory Society vs American Thoracic Society definition.

STUDY OBJECTIVES: To evaluate the distribution of airways obstruction in a general population sample. METHODS: Cross-sectional epidemiologic survey of a general population sample living in Po Delta area (North Italy). Data on respiratory symptoms, diseases, and risk factors were collected through standardized interviewer-administered questionnaires. Lung function tests were performed, with criteria for defining airways obstruction based on the 1995 European Respiratory Society (ERS) statement (FEV(1)/vital capacity ratio < 88% predicted and < 89% predicted in men and women, respectively), "clinical" criteria (FEV(1)/FVC ratio < 70%), and the 1986 American Thoracic Society (ATS) statement (FEV(1)/FVC ratio < 75%). RESULTS: A total of 1,727 subjects aged > 25 years investigated from 1988 to 1991 were included. Prevalence rates of airways obstruction for subjects 25 to 45 years old and subjects >/= 46 years old were as follows: ERS, 10.8% and 12.2%; clinical, 9.9% and 28.8%; and ATS, 27% and 57%, respectively. When considering only moderate/severe obstruction, the rates were as follows: ERS, 0.4% and 3.6%; clinical, 0.3% and 4.4%; and ATS, 0.5% and 5.2%, respectively. The trend was confirmed after stratifying for smoking habit and the presence/absence of respiratory symptoms/diseases. The highest specificity and predictive value for any respiratory symptom/disease was shown by the ERS, and the lowest was shown by the ATS criterion, while the reverse was true for sensitivity; overall accuracy was slightly lower for the ATS criterion. Multiple logistic regression models indicated a higher number of significant associations with known risk factors for airways obstruction according to clinical and ATS criteria than ERS criterion. CONCLUSIONS: The prevalence of COPD in a general population depends very much on the criterion used for definition of airways obstruction. Further research is needed to reach a standardized and epidemiologically consistent criterion for airways obstruction.

Residual volume in a general population. Effects of body size, age, cigarette smoking, and respiratory symptoms.

Residual volume (RV) was obtained by subtracting vital capacity from total lung capacity determined by the single breath helium dilution (TLCsb) to measure CO diffusing capacity in 2,680 subjects (8 to 64 years old) of a general population sample. There were 712 normal subjects (243 male and 469 female subjects) selected to evaluate the pattern of RV by age and to derive reference values for internal comparisons. From 8 to 20 years old, RV showed an increase because of the cross-sectional body size effect; after 20 to 30 years, RV was still increasing, however, at a lower level. Age and height coefficients were significantly related to RV in younger and older ages, both in male and female subjects. The RV percent predicted and RV/TLC percent were higher in smokers when compared to nonsmokers and exsmokers (the difference was significant in male subjects). A dose-response effect was observed between RV percent predicted, RV/TLC percent, and pack-years. The RV percent predicted and RV/TLC percent were significantly higher in smokers and nonsmokers with FEV1 percent predicted below the normal limit (the difference was significant in male subjects). Moreover, higher values of RV percent predicted and RV/TLC percent were observed in subjects with wheezy symptoms in male smokers and nonsmokers. A negative significant correlation was observed between RV/TLC percent and the diffusing capacity adjusted for lung volume (DL/VA) in smokers, exsmokers and nonsmokers of both sexes, confirming the hypothesis that the decrease in DL/VA may be ascribed to the enlargement of terminal air spaces. In conclusion, determination of RV by the single breath helium dilution method is suitable in epidemiology, and it allows additional important information for understanding the physiopathologic mechanisms related to the pathogenesis of chronic obstructive lung disease.

Prevalence rates of respiratory symptoms and diseases in general population samples of North and Central Italy.

SETTING: Four cross-sectional general population surveys in Italy: northern rural Po Delta area (1980-1982, n = 3284; 1988-1991, n = 2841), and central urban Pisa area (1985-1988, n = 3865; 1991-1993, n = 2841). OBJECTIVE: To analyse changes in prevalence rates of respiratory symptoms and diseases. DESIGN: Prospective epidemiological studies by standardised interviewer-administered questionnaire. RESULTS: Prevalence rates of respiratory symptoms and diseases tended to be higher in males (except for dyspnea and pleuritis), in the urban area (more polluted), and in the second surveys; moreover, they increased with age. Asthma peaked in those aged under 25 years and over 64 years. The highest prevalence rates were shown by current smokers of both sexes for all respiratory symptoms and by ex-smoker males for all respiratory diseases, while female current smokers reported chronic bronchitis, emphysema and asthma more frequently. The most clear-cut trend towards increase between the two surveys within each area was exhibited by wheeze and asthma. CONCLUSIONS: These findings highlight the relevance of sex, age and smoking habit, as well as the possible effects of air pollution, in relation to respiratory symptoms. They also indicate a trend towards an increase in asthma symptoms in Italian general population samples in the 1990s, and an under-estimate of medically diagnosed chronic respiratory diseases.

The Po River Delta epidemiological study: use of medicines in a general population sample of north Italy.

Purpose-To provide information on the actual use of medicines in a general population sample.Methods-Information was collected in a general population sample of North Italy (1946 subjects; 938 males, 1008 females) by an interviewer-administered questionnaire.Results-Of the subjects 25.9% took habitually at least one medicine, whereas 11.1% used medicaments only occasionally. The use of medicines was significantly higher in females than in males (p < 0.001), but only in 15-44-year-old females, because of the use of oral contraceptives. The use of medicines increased with ageing (OR=1.80, p < 0.001). The highest use of habitual medicaments was found in subjects of 55+ years of both sexes. In both sexes, the medicines classified in the cardiovascular therapeutic group were the most frequently used. The use of gastrointestinal and cardiovascular medicines was significantly higher in males than in females (p < 0.001). In males, the use of habitual medicines was significantly (p < 0.001) higher in current smokers and ex-smokers than in never smokers. Only 23% of allergic subjects used antiallergic medicines, and only 35% of subjects with respiratory symptoms/diseases used medicines classified into the bronchopulmonary therapeutic group. The percentage of subjects who reported cardiovascular symptoms/diseases and used medicines classified in the cardiovascular therapeutic group was greater (62%).Conclusions-We stress the importance of data collection in general population samples by questionnaires to investigate the actual use of medicines. This may give a more accurate estimate of medicine use than is possible from pharmacy sales or hospital records. Copyright (c) 2000 John Wiley & Sons, Ltd.

Effects of the home environment on respiratory symptoms of a general population sample in middle Italy.

The effects of home environment characteristics were evaluated in a multistage, stratified, cluster sample (N = 3,866) of the general population who lived in the district of Pisa (middle Italy). Each subject completed a standardized interviewer-administered questionnaire that contained questions about respiratory symptoms/diseases and risk factors (e.g., type of heating, fuels used for cooking and heating). Cough and asthma were significantly more frequent in men who did not smoke and who did not use natural gas for cooking and heating. Attacks of shortness of breath accompanied by wheeze, dyspnea, and cardiovascular conditions in female nonsmokers were associated with use of a stove or forced-air circulation for heating; the type of fuel used did not affect this result. Multiple logistic models, which accounted for independent effects of age, smoking status, pack-years, childhood respiratory illness, education, zone of residence, and work exposure to dusts, chemicals, or fumes, showed significantly increased odds ratios for (a) cough and phlegm in males (associated with bottled gas for cooking), (b) wheeze and shortness of breath with wheeze in females (associated with the use of a stove or forced-air circulation). These results, which confirm our previous observations in an unpolluted rural area of north Italy, indicate that characteristics of the home environment, as assessed by questionnaire, may be linked to mild adverse health effects, i.e., respiratory symptoms, in the general population. The results also identify the need to better characterize the dose-response relationship in indoor air pollution monitoring studies that include subsamples of this population.

Prevalence rates of diagnosis of asthma in general population samples of northern and central Italy.

In order to assess the distribution of asthma in Italy in the 1980s, we have compared the findings of three general population surveys carried out in the North and the Centre of the country. Two cross-sectional investigations were performed in the Po Delta area (North Italy), 6 yrs apart: 1) 3,285 subjects, aged 8-64 yrs, in 1980-1982 (PD1); and 2) 2,841 subjects, aged 8-73 yrs, in 1988-1991 (PD2). One cross-sectional survey was carried out in Pisa (Central Italy): 3,866 subjects, aged 5-90 yrs, in 1985-1988 (PI1). For this analysis we have used data from the standardized questionnaires of those subjects between 18-64 yrs, who were currently employed. The prevalence rate of ever asthma was 3.3-5.5%, that of current asthma 1.3-2.9%; almost all of the diagnoses were confirmed by a doctor. Taking into account only doctor-confirmed asthma, the age of onset of manifestations was most frequently over 18 yrs (41-79%). It also occurred more frequently after the onset of employment. As regards smoking, whilst most asthmatic males were current or former smokers (70-86%), most asthmatic females were nonsmokers. However, the situation changed in PD2, where females showed the same pattern as males. Considering asthmatic subjects with skin-prick test reactivity (data available only in PD2), the vast majority (67% in males, 75% in females) had an age of disease onset under 18 yrs. In conclusion, the prevalence of asthma in Italy in the 1980s was similar to that in other European countries and was affected by atopy and smoking differently in the two sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchial reactivity in a general population of north Italy: relationships with occupational exposure.

Two thousand eight hundred and forty one subjects, aged 8-73 yrs, took part in the second cross-sectional survey in the Po River Delta area: among them, a subsample of currently employed people, aged 14-71 yrs, was chosen to establish the relationship between occupational exposure to dusts, chemicals or gases and respiratory symptoms, lung function and bronchial reactivity. Each subject filled out the Italian National Research Council (CNR) standardized questionnaire concerning respiratory symptoms, diseases and risk factors. A variable proportion of subjects performed acceptable forced and slow vital capacity manoeuvres, diffusing capacity of carbon monoxide and bronchial challenge test to methacholine. Occupational exposure appeared to be related to prevalence rate of respiratory symptoms (wheeze, dyspnoea, presence of at least one respiratory symptom) and bronchial asthma. Consistent effects on lung function were not evident. With respect to the bronchial challenge test, using the measurement of the provocative dose producing a 20% fall in forced expiratory volume in one second (PD20) a significantly higher percentage of hyperreactive subjects was found among ex-smoker exposed men; a borderline higher percentage of hyperreactive subjects was also found in non-smoker exposed women. The study findings support the suggestion that occupational exposure may play a role in the development of airway obstructive diseases.

Mortality rates for respiratory disorders in Italy (1979-1990).

Trends in mortality rates for respiratory disorders were investigated in Italy from 1979 to 1990, using data from the Italian Central Statistical Institute (ISTAT). Mortality from lung cancer increased in all age groups, except for those aged 45-64 yrs after 1985. Respiratory diseases showed a consistent reduction; in particular, mortality from emphysema decreased slowly, and mortality from chronic bronchitis showed a significant reduction in all age groups. However, mortality from asthma increased markedly in all age groups up to 1985, and then levelled off and slightly decreased, although remaining at a higher level than in the 1970s. In 1990, data stratified for age group and gender indicated a higher mortality rate in males, that tended to be age-dependent, with the highest rate ratio male/female in those aged 65-74 yrs. Overall, these data indicate a trend to increased mortality from lung cancer and asthma in Italy in the 1980s.

Characteristics of women exposed and unexposed to environmental tobacco smoke (ETS) in a general population sample of North Italy (Po River Delta epidemiological study).

To define qualitative and quantitative categories of exposure to environmental tobacco smoke (ETS) and to assess possible differences for life-style factors between exposed and unexposed women, we studied 867 nonsmoking women (8-73 aged), selected from a general population sample living in the Po Delta area (near Venice, North Italy). Information was collected by a standardized questionnaire. ETS exposure at home, at work or elsewhere was considered. There was a prevalence of ETS exposure of 46% in the whole sample; the rate had a negative association with age. Exposure to ETS occurred more frequently at home, either singly (56%) or in combination with school/work and other places (75%). Exposed women were significantly younger, taller and lighter than those unexposed. Logistic regression on 20+ aged women showed that single-separated-widowed, workers, women living in a rental house, and women with a central forced air heating were significantly more exposed to ETS. Crowding index (n inhabitants/n rooms of the house) was significantly higher in those exposed. These results indicate that ETS exposure is quite frequent in Italian women and that some life-style factors (e.g. marital status or occupational status or some home characteristics), should be considered in the study of relationship between passive smoking and respiratory health.

The Po River Delta epidemiological survey: reference values of total serum IgE levels in a normal population sample of North Italy (8-78 yrs).

The aim of this paper was to define, for the first time in Italy, normal levels of total serum IgE in a general population sample of North Italy. Total serum IgE in 1905 subjects, living in Po Delta area (near Venice), were measured by PRIST method. Normal values were derived from 558 subjects without asthma and/or asthmatic/rhinitic symptoms, noncurrent smokers, skin prick-test negatives ('normals'). Cut-off values to differentiate 'normals' from the remaining part of the sample ('others'), from asthmatic, and from rhinitic subjects, were established with the IgE value midway between the upper limit of the 95% confidence intervals (CI) of the geometric mean for 'normals' and the lower limit for 'others', asthmatics, and rhinitics, respectively. Geometric mean of normal children-adolescents was 45 kU/L (SD: 2.6; 95% CI: 38-63). In normal adults geometric mean was 29 kU/L (SD: 3.3; 95% CI: 25-40) in males and 19 kU/L (SD: 3.8; 95% CI: 16-22) in females. The diagnostic sensitivity of IgE test was low, while the specificity was very high. A good positive predictive value in discriminating 'normals' from 'others' was found, on the contrary, we found a good negative predictive value in discriminating 'normals' from asthmatics or from rhinitics. In conclusion, our results confirm that it is necessary to provide separate total serum IgE reference values for what concerns age in children-adolescents and in adults, and gender, in adults. Low serum IgE are helpful to exclude allergic asthma or rhinitis level of total.

Smooth reference equations for slow vital capacity and flow-volume curve indexes.

We derived reference values for slow vital capacity (VC) and flow-volume curve indexes (FVC, FEV(1), and flows) from the 1,185 tracings provided by 1,039 "normal" subjects who participated in one or both cross-sectional surveys of the Po River Delta study in 1980-1982 and in 1988-1991. Definition of "normal" was based on negative answers to questions on respiratory symptoms/diseases or recent infections, current/past tobacco smoking, and work exposure to noxious agents. Reference equations were derived separately by sex as linear regressions of body mass index (BMI = weight/height(2)), BMI-squared, height, height-squared, and age. Age entered all the models by natural cubic splines using two break points, except for the ratios FEV(1)/VC and FEV(1)/FVC. Random effects models were applied to adjust for the potential intrasubject correlation. BMI, along with height and age, appeared to be an important predictor, which was significantly associated with VC, FEV(1), FVC, FEV(1)/FVC, and PEF in both sexes, and with FEV(1)/VC and FEF(25-75) in females. Natural cubic splines provided smooth reference equation curves (no "jumps" or "angled points") over the entire age span, differently from the conventional reference equations. Thus, we recommend the use of smooth continuous equations for predicting lung function indexes, along with the inclusion of BMI in the equations.

Risk factors for chronic obstructive pulmonary disease in a north Italian rural area.

To assess the role of risk factors for chronic obstructive lung disease (COPD) by multiple logistic models, the data of the first cross-sectional epidemiological survey in the unpolluted rural area of the Po River Delta were analyzed (n = 2382; 20-64 years). Each subject filled out a standardized questionnaire; 94% of the subjects were also able to perform forced expirograms. Dependent variables were chronic respiratory symptoms, asthma, abnormal parameters of flow-volume curve (ABNFVC), and a complex characterized by chronic phlegm, and/or any wheeze and/or dyspnea grade 2+ and/or diagnosis of asthma and/or an FEV1/FVC ratio less than 60% (ANYABN). Independent variables were: age, ever cigarette smoking (SMK) and lifetime cigarette consumption expressed as pack-years, childhood respiratory infections (CRI), adolescence-adulthood respiratory infections (ARI), familial history for COPD (FCOPD) or for asthma/allergies (FASTHMA), work exposure to dusts/chemicals (EXPO), low socio-economic conditions (SES). A significant relationship with almost all dependent variables was shown by pack-years, ARI and age in both sexes. In males, FCOPD was related to chronic mucus hypersecretion and to ABNFVC, FASTHMA was associated with wheeze and ANYABN. EXPO was related to dyspnea and asthmatic symptoms in both sexes and also to bronchitic symptoms in males. CRI was a significant contributor for asthma symptoms in males, for ANYABN in females. SES had no significant association. In conclusion, our findings show that, beside lifetime cigarette smoking, other host--or environment--related conditions are important risk factors for COPD, suggesting the need for a more thorough strategy for prevention.

Effects of daily cigarette consumption on respiratory symptoms and lung function in a general population sample of north-Italian men.

We assessed the respiratory effects of the number of cigarettes smoked daily (CIGD) in 748 male smokers of a general population sample living in the unpolluted area of the Po Delta (Italy). A standardized questionnaire, flow-volume curves (V/V), the diffusing capacity of carbon monoxide (DLCO) and the slope of the alveolar plateau of nitrogen (DN2%/l) were used. Subjects were divided according to the median value of the observed distribution of CIGD (1-19, 20+) and according to the tertile values of the observed distribution of pack-years (an index representing lifetime cigarette consumption; 1-7, 8-21, 22+). In those with a higher CIGD, the prevalence rate of chronic phlegm was always significantly increased, while the prevalence rate of wheeze was significantly higher if they had smoked 8+ pack-years. Using analysis of variance, adjusted for pack-years, DLCO indexes, FEF75-85 and Vmax75 were significantly reduced in those with higher CIGD. When multiple logistic models, accounting for the independent effects of age and pack-years, were used, significantly increased odds ratios (ORs) for symptoms (e.g. OR = 2.0 for phlegm, OR = 1.8 for cough, OR = 1.6 for wheeze) and abnormal DLCO (OR = 1.9) or DN2%/l (OR = 1.6) were associated with a daily consumption of 10 cigarettes. In conclusion, the amount of cigarettes currently smoked may add a negative effect to that caused by lifetime cigarette consumption on respiratory symptoms and lung function. Moreover, the use of diffusing capacity in general population surveys is advisable.

Serum immunoglobulins E are related to menstrual cycle.

During a cross sectional epidemiological survey on a general population sample, 596 fertile women underwent total serum IgE determination. They completed an interviewer-administered standardized questionnaire and were categorized according to their menstrual period. They were divided into two groups: those from days 10 to 20, who were considered to be in the periovulatory phase, and those in the other phases. IgE mean values were significantly different (p = 0.01) in the two groups: particularly, lower IgE values were found in those in periovulatory phase, after accounting for smoking habit and atopic status. By multiple regression analysis, taking into account the independent effects of menstrual period, age, smoking habit, hours of fast, skin prick test reactivity and presence of cough, significantly lower IgE values in the periovulatory phase were found. We hypothesize the possibility that a decrease of IgE concentration occurs during midcycle: a reduced immune response might facilitate the ovuli implantation. Further studies are necessary to longitudinally investigate the trend of IgE in the same women, as well as the distributions and the trends of other immunoglobulins.

Distribution of bronchial responsiveness in a general population: effect of sex, age, smoking, and level of pulmonary function.

Bronchial responsiveness (BR) was assessed by the methacholine challenge test in 1,694 subjects from a sample of the general population (aged 8 to 73 yr) enrolled in a prospective epidemiologic study on the natural history of chronic obstructive pulmonary disease (COPD). Information on respiratory symptoms and risk factors for COPD were obtained with a standardized questionnaire. The provocative dose causing a 10%, 15%, and 20% decrease in FEV1 was reached in 939 (55%), 658 (39%), and 447 (26%) subjects, respectively, after the last cumulative dose of methacholine (i.e., 4.8 mg). The slope of the dose-response curve was also computed in order to attribute a parameter to subjects who did not reach the provocative dose. After natural log transformation, the slope (Ln Slope) of the curve showed a significant association with the degree of airway obstruction, as assessed by FEV1% predicted, FEV1/VC%, and FEV1/FVC%. Therefore, relationships between BR, sex, age, and smoking were evaluated after adjustments for the initial airway caliber (FEV1, FEV1 adjusted for height, and FEV1/VC%). Females showed significantly higher values of Ln Slope than did males after adjustments were made for baseline lung function. In males, higher BR was observed in childhood-adolescence age groups and at older ages, while in females a higher level of BR was observed during childhood. Significantly higher Ln Slope values were found for females who currently smoked than for non- and ex-smokers. No difference was observed in males in relation to smoking habit. (ABSTRACT TRUNCATED AT 250 WORDS)

The Po River Delta Respiratory Epidemiological Survey: an analysis of factors related to level of total serum IgE.

The purpose of the present study was to analyse whether sex, age, skin test reactivity, cigarette smoking and occupational exposure were related to the total serum immunoglobulin (Ig)E concentrations (kU x L[-1]), in a general population sample. We studied 1,905 subjects (915 males, 990 females) of a general population sample (n=2,841, 8-73 yrs) participating in the second cross-sectional respiratory epidemiological survey in the rural Po Delta area (near Venice, North Italy). Distribution of total serum IgE concentrations was skewed, thus a log-transformation was performed to obtain a Gaussian shape. Significantly higher values of IgE were found in males compared to females. In general, a peak of IgE concentration was found at 8-14 yrs. IgE values tended to be lower in older than younger adults. Significantly higher serum IgE levels were shown in subjects with a positive skin-prick test index (ST+) than in those with a negative skin-prick test index (ST-). There was a significant relationship of total IgE levels with skin reactivity to pollens and house-dust mites. In both sexes higher values of IgE were found in current smokers than in ex-nonsmokers, regardless of skin-test reactivity. There was no significant difference in IgE values between ex- and nonsmokers. Passive smoking and occupational exposure were significantly related to increased IgE values. Our results confirm that in a general population sample immunoglobulin E concentrations are related not only to skin-prick test reactivity to common aeroallergens, but also to other risk factors for chronic obstructive lung diseases, such as sex, active/ passive smoking and occupational exposure.

Skin prick test reactivity to common aeroallergens in relation to total IgE, respiratory symptoms, and smoking in a general population sample of northern Italy.

Skin prick test (SPT) reactivity to common airborne allergens and its relationships to sex, age, smoking habits, and respiratory symptoms/diseases were evaluated in a general population sample (n = 2841, 8-75 years of age) living in the Po delta area (northern Italy). Subjects completed a standardized questionnaire and underwent prick tests (12 local allergens, a negative and a positive control) and determination of total serum IgE. Atopy was evaluated by measuring the maximal diameter for each allergen, after subtracting that of the negative control. Thirty-one percent of subjects showed a positive skin response at a 3-mm threshold. Pollens, Dermatophagoides pteronyssinus, and D. farinae caused the highest frequencies of reactions. Young people and those who had never smoked had higher prevalence rates of SPT reactivity. Asthma, asthma symptoms, and rhinitis were significantly associated with SPT reactivity in both sexes (cough only in females) and with the number of positive reactions. IgE values were also significantly associated with SPT reactivity. In conclusion, our findings indicate that almost one-third of the general population of an Italian rural area is skin test positive, emphasizing the importance of assessing atopy in respiratory epidemiologic surveys.

CO diffusing capacity in a general population sample: relationships with cigarette smoking and airflow obstruction.

The single-breath carbon monoxide diffusing capacity (DLCOsb) was measured together with ventilatory lung function tests as part of a survey of a general population sample living in Northern Italy (n = 2,481). Based on answers to an interviewer-administered questionnaire, subjects free of respiratory symptoms or diseases were identified. Data from subjects who had never regularly smoked cigarettes were used to derive reference equations for the test indexes, and data from the remaining subjects who had smoked were used to derive regression equations incorporating a term expressing cigarette consumption (cube root of pack-years) and a term indicating current smoking decrement, in order to obtain expected DLCOsb percent predicted. Neither number of cigarettes smoked daily or duration of smoking, in smokers, nor duration of smoking or years since quitting smoking, in ex-smokers, entered significantly the multiple-regression model. The mean values of DLCOsb were only slightly affected by the increasing degree of airway obstruction. When subjects with confirmed asthma were analyzed, after stratifying for different levels of FEV1/FVC ratio, increased mean value of DLCOsb (over 100%) was found in those with an FEV1/FVC ratio between 75 and 65%. This cross-sectional analysis suggests that there is a decrease in DLCOsb with cumulative cigarette consumption even in healthy subjects. Further, it confirms the clinical observations of high DLCOsb values in asthmatic patients, at least in those with an initial degree of chronic airflow obstruction.