Bronchial responsiveness to methacholine was examined in a Norwegian general population sample (n = 490) 18 to 73 yr of age. Altogether, 20 and 6% of the sample had PC20 less than or equal to 32 mg/ml and PC20 less than or equal to 8 mg/ml, respectively. The relationship of bronchial responsiveness to the following potential predictors were examined: sex, age, smoking habits, airway caliber (FEV1), FEV1 percent predicted (%FEV1), urban-rural area of residence, occupational airborne exposure in present job, and total serum IgE. After adjusting for age and FEV1, the odds ratio for PC20 less than or equal to 32 mg/ml was higher for men than for women in smokers and in ex-smokers, but did not vary by sex in nonsmokers, the adjusted odds ratio for PC20 less than or equal to 32 mg/ml in male compared with female smokers being 8.4 (95% Cl: 2.5-37.4). Irrespective of smoking status the sex- and FEV1-adjusted odds ratio for PC20 less than or equal to 32 mg/ml fell with increasing age. For every 10-yr increase in age the adjusted odds ratio for PC20 less than or equal to 32 mg/ml methacholine in nonsmokers decreased by 2.0 (95% Cl: 1.3-3.3). Also FEV1 and %FEV1 were predictors of PC20 less than or equal to 32 mg/ml after adjusting for sex and age irrespective of smoking status. Bronchial responsiveness (PC20 less than or equal to 8 mg/ml) was more prevalent in rural than in urban areas, the adjusted odds ratio being 2.5 (95% Cl: 1.1-5.9) for bronchial responsiveness in rural compared with urban residents after adjusting for sex, age, smoking habits, and FEV1.(ABSTRACT TRUNCATED AT 250 WORDS)
The purpose of this survey was to evaluate the effects of smoking and occupational exposures on the decline in forced expiratory volume in one second (FEV1), and the presence of airflow limitation (FEV1 x100/forced vital capacity (FVC) being
Comment In: Eur Respir J. 1993 Sep;6(8):1088-98224120
We aimed to investigate whether dietary vitamin C intake, an important antioxidant, is inversely related to self-reported respiratory symptoms in young adults of a community. A random sample of 4300 subjects, aged 20-44 years, living in Bergen, Norway, received a postal questionnaire on respiratory symptoms; 80% responded. Vitamin C intake (mg per week) was estimated from a food-frequency questionnaire asking how often the subject, during the last year, had consumed units of orange juice, oranges, potatoes, carrots and tomatoes. Significant differences in the intake of vitamin C were observed across smoking categories with current smokers having the lowest intake, while there was no variation by gender, age or occupational dust exposure. Dietary vitamin C intake was in univariate analyses inversely related to "morning cough", "chronic cough", "wheeze" and "wheeze ever". After adjusting for gender, age, body mass index, "occupational exposure" pack-years as well as having and stratified on smoking habits in multiple logistic regression analyses, the relationship between dietary vitamin C intake and "cough" and "wheeze" tended to be associated to smoking. The odds ratio (OR) for "morning cough" was 0.68 (95% CI: 0.35-0.95), "chronic cough" OR 0.69 (95% CI: 0.47-1.04) and "wheeze ever" OR 0.75 (95% CI: 0.56-1.01) in current-smokers with dietary vitamin C intake in the upper (> or =395 mg/ week) vs. the lower (
The relation of educational level to obstructive lung disease, spirometric airflow limitation, and respiratory symptoms was examined in a two-phase cross-sectional study of a Norwegian general population aged 18-73 years in 1985-1988. The first phase was a questionnaire survey. In the second phase, a stratified sample of those who responded in the first phase was invited to a clinical and respiratory physiologic examination. Altogether, 714 subjects attended, representing 84% of those invited. The prevalences of obstructive lung disease and spirometric airflow limitation were 7.8% and 4.5%, respectively. A total of 18% of the population had completed college, a further 60% had completed secondary school, and 21% had obtained a primary school education alone. The prevalence of both smoking and occupational airborne exposure decreased with increasing educational level. The sex-, age-, smoking-, and occupational exposure-adjusted odds ratio of obstructive lung disease in primary-versus university-educated subjects was 2.9 (95% confidence interval (CI) 1.3-6.5); in secondary- versus university-educated subjects it was 1.4 (95% CI 0.7-2.8). The corresponding values for spirometric airflow limitations were 5.2 (95% CI 2.0-13.4) and 1.8 (95% CI 1.2-2.7). All of the respiratory symptoms except breathlessness grade 2 were significantly associated with educational level after allowing for sex, age, smoking, and occupational airborne exposure. The survey indicates that educational level is a risk factor for airway disorders independent of smoking and occupational airborne exposure.
We examined the effects from subjects, technicians and spirometers on within-session variability in successful recordings of forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in 4989 asymptomatic never-smoking men. All eligible men aged 30-46 years living in western Norway (n = 45,380) were invited to a cross-sectional community survey. Information on respiratory symptoms, smoking habits and occupational exposures was obtained from a self-administered questionnaire. Three successful FEV1 and FVC recordings were obtained in 26,368 attendants using three dry-wedge bellow spirometers operated by 10 different technicians. Within-subject standard deviation (SD) from three recordings of FEV1 and FVC was on average 102 and 106 ml, respectively, and increased with height (14 and 17 ml, respectively, per 10 cm) and body mass index (BMI) (11 and 14 ml, respectively, per 5 kg m-2). Between-subject SD of the mean of three FEV1 and FVC recordings was 591 and 754 ml, respectively, and increased in groups of increasing height (43 and 40 ml, respectively, per 10 cm). Small, but significant, differences were observed between technicians in within-subject SD and in levels of FEV1 and FVC. Homogeneity of between-subject variability, necessary for linear regression analysis, was obtained using FEV1 and FVC divided by height squared. In conclusion, within-subject variability in three successful spirometric recordings was small, but dependent on height and BMI of the subjects as well as technician performance. The observed heterogeneity in between-subject variation in FEV1 and FVC levels disappeared when each variable was divided by height squared. Novel multiple linear regression equations for FEV1/height2 and FVC/height2 were developed to be used in evaluating the effects from occupational airborne exposures in Nordic men aged 30-46 years.
Longitudinal studies have reported an association between early childhood lung disease and adult respiratory disease. This issue has not been addressed in the Nordic countries. We studied the association between hospitalization for lung disease in early childhood and asthma in young adulthood in a Norwegian population sample, while estimating the attributable fraction of childhood hospitalization. A population-based survey in Bergen, Norway included a random sample of 4300 subjects aged 20-44 years, of whom 80% responded. The effect of hospitalization for lung disease before the age of 2 years on asthma in adulthood was analysed by logistic and polytomous logistic regressions, adjusting for related variables. Adjusted attributable fractions were estimated from these models. The risk for different measures of asthma was significantly increased in the 103 persons reporting childhood hospitalization (airways symptoms: OR from 1.9 to 2.9; asthma medication: OR = 2.8). The associations with airways symptoms were stronger in women (OR from 2.6 to 5.3) than in men (OR from 1.4 to 2.4). Given a causal association, adjusted attributable fractions showed that childhood lung disease causing hospitalization explained 4% of asthma symptoms. Early childhood hospitalization for lung disease was related to asthma symptoms in young Norwegian adults, more strongly in women than in men. Only a minor proportion of asthma symptoms in this age group could be related to hospitalization for lung disease in early childhood.
Some children develop asthma and other atopic diseases, others asthma without atopic diseases. To better understand secular trends, we estimated the relative increase in asthma in children with (atopy related asthma) and without (non-atopy related asthma) other atopic diseases (eczema or hay fever) in two samples of school children born, 1965-1975 (n = 1674) and 1978-1988 (n = 2188). By analysing the samples as historical cohorts, age-specific prevalence rates were estimated and incidence rates were calculated (number of new cases by 1000 person years under risk). Cox regression was used to estimate the relative risk (RR) of asthma by year of birth. The point prevalence of asthma was 1.9% (95% CI: 1.4-2.4) in the 1965-1975 cohort and 4.6% (95% CI: 3.8-5.4) in the 1978-1988 cohort for three-year old children, and remained fairly constant throughout childhood. The age-specific prevalence of non-atopy related asthma increased relatively more from 1965-1975 to 1978-1988 compared to atopy related asthma. The age-specific incidence rates of asthma showed that the RRs comparing the two cohorts tended at all ages to be highest for non-atopy related asthma. The relative risks of non-atopy related asthma by gender and birth cohort, showed that the effect of cohort was higher for non-atopy related asthma, aRR: 4.0 (95 % CI: 2.5-6.5), than for atopy-related asthma aRR: 2.0 (95% CI: 1.3-3.2). Children without other atopic diseases have a higher relative risk of being diagnosed with asthma than children with other atopic diseases across all ages comparing two samples of school children born 1965-1975 and 1978-1988.
Reduced single-breath transfer factors of the lung for carbon monoxide are seen in a number of conditions. The hypothesis of the present study was that self-reported respiratory symptoms differ in their prediction of TL,CO level in a general population in Norway. A cross-sectional survey of a general population sample in Norway, made up of 1,275 subjects aged 18-73 yrs, was conducted in 1987-1988. The attendees (84% response rate) filled in a questionnaire on respiratory symptoms and underwent standardized spirometric and TL,CO measurements and clinical examination. Associations between TL,CO and respiratory symptoms were assessed using multiple regression models. Tests for interaction were used to examine whether these associations varied with sex, age and smoking habits. Data from 1,221 subjects were analysed. Both males and females who reported respiratory symptoms had significantly lower TL,CO after adjusting for age and height. In a multiple linear regression analysis of TL,CO, adjusting for sex, age, height and smoking habits, the symptoms for which statistical significance was attained, were morning cough, chronic cough and breathlessness. However, only the breathlessness score was independently associated with the TL,CO (-0.42 mmol x min(-1) x kPa(-1) per breathlessness score unit) after adjusting for other respiratory symptoms, and the relationship was stronger in males than in females. In this study, the strongest predictor for a decreased single-breath transfer factor of the lung for carbon monoxide was the presence of self-reported breathlessness, regardless of age, smoking habits and height.
We studied tuberculin reactivity in young Norwegian adults and its possible dependency on age, gender, previous BCG vaccination, smoking habits, occupational exposure, diet as well as years of education as a measure of socio-economic status. Responders of a random sample of men and women aged 20-44 years living in Bergen, Norway were interviewed and tested withthe adrenaline-Pirquettest with Norwegian-produced synthetic mediumtuberculin at the out-patient chest clinic in the city of Bergen in 1992-1993. Nine hundred and three subjects out of 1200 met for the clinical examination (75%). Five hundred and eighty-eight subjects were tuberculin-tested and read, whereof 95% were BCG vaccinated by age 14. Mean tuberculin reactivity was 4.8 mm (SD: 3.0 mm). A positive reaction (> or = 4 mm) was found in 64%, whereof 7% had a strongly positive reaction (>10 mm). A negative reaction (