Obstructive Lung Disease In Northern Sweden Research Articles

Is asthma in children still increasing? 20-year prevalence trends in northern Sweden.

In the present study, we describe prevalence trends of asthma and investigate the association with asthma symptoms, use of asthma medication, and asthma severity among 8-year-old children in Norrbotten, Sweden in 1996, 2006, and 2017. Within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, three pediatric cohorts were recruited in 1996, 2006, and 2017 respectively. Identical methods were used; all children in first and second grade (median age 8 years) in three municipalities were invited to a parental questionnaire survey, completed by n = 3430 in 1996 (97% participation), n = 2585 in 2006 (96%), and n = 2785 in 2017 (91%). The questionnaire included questions about respiratory symptoms and diagnosis, treatment, and severity of asthma. The prevalence of wheezing was stable during the study, 10.1% in 1996; 10.8% in 2006; and 10.3% in 2017, p = .621, while physician-diagnosed asthma increased: 5.7%, 7.4%, and 12.2%, p < .001. The use of asthma medication in the last 12 months increased: 7.1%, 8.7%, and 11.5%, p < .001. Among children diagnosed with asthma, the prevalence of asthma symptoms, the impact on daily life, and severe asthma decreased, while the use of inhaled corticosteroids increased from 1996 until 2017. The prevalence of wheezing was stable among 8-year-old in this area from 1996 to 2017, while the prevalence of physician-diagnosed asthma doubled but without an increase in asthma morbidity. The increase of physician-diagnosed asthma without a coincident increase in asthma morbidity can partly be explained by more and earlier diagnosis among those with mild asthma.

Electronic cigarette use in relation to changes in smoking status and respiratory symptoms.

How e-cigarette use relates to changes in smoking status and respiratory symptoms in the population remains controversial. The aim was to study the association between e-cigarette use and, changes in smoking status and changes in respiratory symptoms. A prospective, population-based study of random samples of the population (age 16-69 years) was performed within The Obstructive Lung Disease in Northern Sweden (OLIN) study and West Sweden Asthma Study (WSAS). A validated postal questionnaire containing identical questions was used in OLIN and WSAS at baseline in 2006-2008 and at follow-up in 2016. In total, 17325 participated on both occasions. Questions about respiratory symptoms and tobacco smoking were included in both surveys, while e-cigarette use was added in 2016. In 2016, 1.6% used e-cigarettes, and it was significantly more common in persistent tobacco smokers (10.6%), than in those who quit smoking (2.1%), started smoking (7.8%), or had relapsed into tobacco smoking at follow-up (6.4%) (p<0.001). Among current smokers at baseline, tobacco smoking cessation was less common in e-cigarette users than e-cigarette non-users (14.2% vs 47.6%, p<0.001) and there was no association with a reduction in the number of tobacco cigarettes smoked per day. Those who were persistent smokers reported increasing respiratory symptoms. In contrast, the symptoms decreased among those who quit tobacco smoking, but there was no significant difference in respiratory symptoms between quitters with and without e-cigarette use. E-cigarette use was associated with persistent tobacco smoking and reporting respiratory symptoms. We found no association between e-cigarette use and tobacco smoking cessation, reduction of number of tobacco cigarettes smoked per day or reduction of respiratory symptoms.

Diagnostic intervention improved health-related quality of life among teenagers with food allergy.

The aim was to examine if a diagnostic intervention set up to assess current food allergy to cow's milk, hen's egg, fish, or wheat among teenagers had an impact on generic and disease specific health-related quality of life (HRQL). The study compared HRQL scoring before and two years after the intervention, and in relation to age matched controls without reported food allergy. The study was performed within the Obstructive Lung Disease in Northern Sweden (OLIN) studies where a cohort study on asthma and allergic diseases among 8-year-old schoolchildren was initiated in 2006. At age 12 years, the 125/2612 (5%) children who reported allergy to cow's milk, hen's egg, fish, or wheat were invited to a diagnostic intervention including clinical examination, blood tests and evaluation by a pediatric allergist. Of 94 participants, 79 completed generic and disease specific HRQL questionnaires. Additionally, a random sample of 200 (62% of invited) children without food allergy from the OLIN cohort answered the generic HRQL questionnaire. The respondents of the HRQL questionnaires were re-examined two years later and 57 teenagers with and 154 without reported allergy participated. There were no significant differences in generic HRQL scores between teenagers with and without reported food allergy at study entry, or after the intervention. Among those with reported food allergy, we found a significant improvement in disease specific HRQL after the intervention (mean values: 3.41 vs 2.80, p<0.001). Teenagers with only food allergy had better disease specific HRQL compared to those with one, two or three concomitant allergic diseases, both before and after the intervention. Children with only food allergy significantly improved their HRQL after the intervention, 1.84 vs. 2.87 (p<0.001) but this association was not seen in children with one other allergic disorder (3.16 vs. 3.65, p = 0.121) or those with two or more allergic disorders (3.72 vs. 3.90, p = 0.148). The diagnostic intervention showed a long-term improvement of disease specific HRQL but not generic HRQL.

All-cause and cause-specific mortality by spirometric pattern and sex - a population-based cohort study.

Chronic airway obstruction (CAO) and restrictive spirometry pattern (RSP) are associated with mortality, but sex-specific patterns of all-cause and specific causes of death have hardly been evaluated. To study the possible sex-dependent differences of all-cause mortality and patterns of cause-specific mortality among men and women with CAO and RSP, respectively, to that of normal lung function (NLF). Population-based prospective cohort study. Individuals with CAO [FEV1/vital capacity (VC) < 0.70], RSP [FEV1/VC ⩾ 0.70 and forced vital capacity (FVC) < 80% predicted] and NLF (FEV1/VC ⩾ 0.70 and FVC ⩾ 80% predicted) were identified within the Obstructive Lung Disease in Northern Sweden (OLIN) studies in 2002-2004. Mortality data were collected through April 2016, totally covering 19,000 patient-years. Cox regression and Fine-Gray regression accounting for competing risks were utilized to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for age, body mass index, sex, smoking habits and pack-years. The adjusted hazard for all-cause mortality was higher in CAO and RSP than in NLF (HR, 95% CI; 1.69, 1.31-2.02 and 1.24, 1.06-1.71), and the higher hazards were driven by males. CAO had a higher hazard of respiratory and cardiovascular death than NLF (2.68, 1.05-6.82 and 1.40, 1.04-1.90). The hazard of respiratory death was significant in women (3.41, 1.05-11.07) while the hazard of cardiovascular death was significant in men (1.49, 1.01-2.22). In RSP, the higher hazard for respiratory death remained after adjustment (2.68, 1.05-6.82) but not for cardiovascular death (1.11, 0.74-1.66), with a similar pattern in both sexes. The higher hazard for all-cause mortality in CAO and RSP than in NLF was male driven. CAO was associated with respiratory death in women and cardiovascular death in men, while RSP is associated with respiratory death, similarly in both sexes.

Early-life risk factors for development of asthma from 8 to 28 years of age: a prospective cohort study.

The objective was to estimate the incidence rate of asthma from age 8 to 28 years and evaluate early-life risk factors for asthma onset at different ages. In 1996, within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a cohort of 3430 schoolchildren (97% of invited) was recruited at age 8 years to a prospective study about asthma. The cohort was followed annually from age 8 to 19 years and at 28 years by questionnaire surveys (67% of the original cohort participated). Asthma was categorised as never-asthma, onset age ≤8 years, onset age 9-13 years, onset age 14-19 years or onset age >19 years. Of the 3430 individuals in the cohort, 690 (20.1%) reported asthma in any survey. The average incidence rate was 10.0/1000 per year at ≤8 years, 11.9/1000 per year at 9-13 years, 13.3/1000 per year at 14-19 years and 6.1/1000 per year at >19 years. The incidence was higher among boys until age 10 years, but from age 15 years, it became higher among girls. Family history of asthma, allergic sensitisation and breastfeeding <3 months were associated with asthma onset throughout the study. Low birthweight, maternal smoking during pregnancy, severe respiratory infection, rhinoconjunctivitis and eczema were associated with asthma onset ≤8 and 9-13 years. The incidence of asthma was high during childhood and the teenage period, and decreased substantially during young adulthood. Early-life factors were associated with asthma onset throughout childhood but had also a lasting effect on asthma incidence until adulthood.

Socioeconomic inequalities in asthma and respiratory symptoms in a high-income country: changes from 1996 to 2016

Objective: Low socioeconomic status based both on educational level and income has been associated with asthma and respiratory symptoms, but changes over time in these associations have rarely been studied. The aim was to study the associations between educational or income inequality and asthma and respiratory symptoms among women and men over a 20-year period in northern Sweden. Methods: The study was performed within the Obstructive Lung disease in Northern Sweden (OLIN) research program. Mailed questionnaire surveys were administered to a random sample of adults (20-69 years of age) living in Sweden, in 1996, 2006 and 2016. Data on educational level and income were collected from the national integrated database for labor market research. Results: The educational inequality associated with asthma and asthmatic wheeze tended to decrease from 1996 to 2016, while it increased for productive cough, the latter among men not among women. The income inequality decreased for productive cough, especially for women, while no clear overall trends were found for asthmatic wheeze and asthma, apart from a decrease in income inequality regarding asthma among men. Conclusion: The patterns for socioeconomic inequality differed for asthma and wheeze compared to productive cough, and the results emphasize that education and income do not mirror the same aspects of socioeconomic inequality in a high-income country. Our findings are important for decision makers, not the least on a political level, as reduced inequality, e.g. through education, could lead to reduced morbidity.

Severe alpha‐1‐antitrypsin deficiency increases the risk of venous thromboembolism

BackgroundSevere alpha‐1‐antitrypsin deficiency (AATD), phenotype PiZZ, is associated with increased risk of liver disease and chronic obstructive pulmonary disease (COPD), but the risk of venous thromboembolism (VTE) is unknown. Our aim was to evaluate the risk of VTE in individuals with severe AATD compared with control subjects from the general population. MethodsIndividuals with severe AATD (n = 1577) were recruited from the Swedish national AATD register. Control subjects (n = 5969) were selected from the OLIN (Obstructive Lung Disease in Northern Sweden) studies, that include a random general population sample. Longitudinal data on VTE and diagnoses were obtained from the Swedish National Patient Registry. Associations were analyzed using multivariable Cox regression. ResultsAt inclusion, 46% of the AATD individuals and 53% of the controls were never‐smokers. COPD was present in 46% of the AATD individuals compared with 4% of the controls. During a median follow‐up of 18 years, 116 (7%) of the AATD individuals and 89 (1%) of the control subjects developed VTE, unadjusted hazard ratio 6.5 (95% confidence interval 4.9–8.6). Risk factors for incident VTE were male gender, age, COPD, cancer, and liver disease. Adjusting for these factors, the AATD individuals had a significantly higher risk of incident VTE, adjusted hazard ratio 4.2 (95% confidence interval 2.9–6.2) as compared with the controls. ConclusionSubjects with severe AATD have considerably increased risk of developing VTE compared with the general population, even after accounting for risk factors. This calls for optimized risk factor management and clinical follow‐up of this patient group.

High but stable incidence of adult-onset asthma in northern Sweden over the last decades.

BackgroundThe prevalence of asthma has increased both among children and adults during the latter half of the 20th century. The prevalence among adults is affected by the incidence of asthma not only in childhood but also in adulthood. Time trends in asthma incidence have been poorly studied.AimsThe aim of this study was to review the incidence of adult-onset asthma from 1996 to 2006 and 2006 to 2016 and compare the risk factor patterns.MethodsIn the Obstructive Lung Disease in Northern Sweden (OLIN) studies, two randomly selected population-based samples in the 20–69-year age group participated in postal questionnaire surveys about asthma in 1996 (n=7104, 85%) and 2006 (n=6165, 77%). A 10-year follow-up of the two cohorts with the same validated questionnaire was performed, and 5709 and 4552 responded, respectively. Different definitions of population at risk were used in the calculations of asthma incidence. The protocol followed a study performed between 1986 and 1996 in the same area.ResultsThe crude incidence rate of physician-diagnosed asthma was 4.4 per 1000 person-years (men 3.8, women 5.5) from 1996 to 2006, and 4.8 per 1000 person-years (men 3.7, women 6.2) from 2006 to 2016. When correcting for possible under-diagnosis at study entry, the incidence rate was 2.4 per 1000 person-years from 1996 to 2006 and 2.6 per 1000 person-years from 2006 to 2016. The incidence rates were similar across age groups. Allergic rhino-conjunctivitis was the main risk factor for incident asthma in both observation periods (risk ratio 2.4–2.6).ConclusionsThe incidence of adult-onset asthma has been stable over the last two decades and has remained at a similar level since the 1980s. The high incidence contributes to the increase in asthma prevalence.

Severe asthma is related to high societal costs and decreased health related quality of life.

The aim of the present study was to estimate the societal costs and the key cost drivers for patients with severe asthma in Sweden. In addition, health-related quality of life (HRQOL) and morbidity of patients with severe asthma is described. The study population comprised adults with severe asthma recruited from a large asthma cohort within the Obstructive Lung Disease in Northern Sweden (OLIN) studies. During 2017, patients were interviewed quarterly over telephone regarding their resource utilization and productivity losses. Estimated mean annual asthma-related costs per patient with severe asthma amounted to €6,500, of which approximately €2400 and €4100 were direct and indirect costs, respectively. The main cost drivers for direct costs were hospitalizations followed by drugs: approximately €1000 and €800, respectively. Patients on treatment with regular oral corticosteroids (OCS) had greater direct costs compared with those without regular OCS treatment. Co-morbid conditions were common and the costs were substantial also for co-morbid conditions, with a total cost of approximately €4200. The OCS group had significantly lower HRQOL compared to the non-OCS group. The societal costs due to severe asthma were substantial. Costs for co-morbid conditions contributed substantially to both direct and indirect costs. The direct costs were significantly higher in the maintenance OCS-group compared to the non-maintenance OCS-group. These results indicate a need for improved management and treatment regimens for patients with severe asthma.

Association of Electronic Cigarette Use With Smoking Habits, Demographic Factors, and Respiratory Symptoms

There is an ongoing debate about whether electronic cigarettes (e-cigarettes) are the solution to the tobacco epidemic or a new public health threat. Large representative studies are needed to study e-cigarette use in the general population, but hardly any have been published. To estimate the prevalence of e-cigarette use and to investigate the association of e-cigarette use with smoking habits, demographic factors, and respiratory symptoms. Cross-sectional, population-based study of random samples of the population, performed within the Obstructive Lung Disease in Northern Sweden (OLIN) study and West Sweden Asthma Study (WSAS). The same validated questionnaire including identical questions was used in OLIN and WSAS. In 2016, OLIN and WSAS conducted postal questionnaire surveys in random samples of adults aged 20 to 75 years. In OLIN, 6519 participated (response rate, 56.4%); in WSAS, 23 753 participated (response rate, 50.1%). Electronic cigarette use, smoking habits, and respiratory symptoms. Of 30 272 participants (16 325 women [53.9%]), 3897 (12.9%) were aged 20 to 29 years; 4242 (14.0%), 30 to 39 years; 5082 (16.8%), 40 to 49 years; 6052 (20.0%), 50 to 59 years; 6628 (21.9%), 60 to 69 years; and 4371 (14.4%), 70 to 75 years. The number of current smokers was 3694 (12.3%), and 7305 (24.4%) were former smokers. The number of e-cigarette users was 529 (2.0%), and e-cigarette use was more common among men (275 of 12 347 [2.2%; 95% CI, 2.0%-2.5%]) than women (254 of 14 022 [1.8%; 95% CI, 1.6%-2.0%]). Among current smokers, 350 of 3566 (9.8%; 95% CI, 8.8%-10.8%) used e-cigarettes compared with 79 of 6875 (1.1%; 95% CI, 0.9%-1.3%) in former smokers and 96 of 15 832 (0.6%; 95% CI, 0.5%-0.7%) in nonsmokers (P < .001). Among e-cigarette users who answered the survey question about cigarette-smoking habits (n = 525), 350 (66.7%; 95% CI, 62.7%-70.7%) were current smokers, 79 (15.0%; 95% CI, 11.9%-18.1%) were former smokers, and 96 (18.3%; 95% CI, 15.0%-21.6%) were nonsmokers (P < .001 for trend). In a regression analysis, e-cigarette use was associated with male sex (odds ratio [OR], 1.35; 95% CI, 1.12-1.62); age groups 20 to 29 years (OR, 2.77; 95% CI, 1.90-4.05), 30 to 39 years (OR, 2.27; 95% CI, 1.53-3.36), 40 to 49 years (OR, 1.65; 95% CI, 1.11-2.44), and 50 to 59 years (OR, 1.47; 95% CI, 1.01-2.12); educational level at primary school (OR, 1.99; 95% CI, 1.51-2.64) and upper secondary school (OR, 1.57; 95% CI, 1.25-1.96); former smoking (OR, 2.37; 95% CI, 1.73-3.24); and current smoking (OR, 18.10; 95% CI, 14.19-23.09). All respiratory symptoms were most common among dual users and former smokers and nonsmokers who used e-cigarettes. Use of e-cigarettes was most common among smokers, and dual users had the highest prevalence of respiratory symptoms. On a population level, this study indicates that the present use of e-cigarettes does not adequately serve as a smoking cessation tool.

Population-based study shows that teenage girls with asthma had impaired health-related quality of life.

This study examined the health-related quality of life (HRQoL) of teenagers with and without asthma, including the impact of their sex, allergic conditions, smoking, living conditions and physical activity. The Obstructive Lung Disease in Northern Sweden (OLIN) studies recruited a cohort of schoolchildren in 2006. The parents of all children aged seven to eight years in three municipalities were invited to complete a questionnaire and 2585 (96%) participated. The cohort was followed up at the ages of 11-12 years and 14-15 years with high participation rates. At 14-15 years, the HRQoL questionnaire KIDSCREEN-10 and Asthma Control Test were added. Girls with current asthma at 14-15 years had a lower mean HRQoL score than girls without asthma (46.4 versus 49.3, p < 0.001), but this was not seen among boys (53.8 versus 52.8, p = 0.373). Poor HRQoL was related to current asthma, uncontrolled asthma and teenage onset of asthma. It was also related to eczema, living in a single-parent household, maternal smoking, daily smoking and inversely related to physical activity. Teenage girls with asthma had lower HRQoL than girls without asthma. Possible interventions to improve HRQoL among teenagers with asthma were identified as follows: increasing asthma control, preventing smoking and promoting physical activity.

Targeted high-throughput sequencing of candidate genes for chronic obstructive pulmonary disease.

BackgroundReduced lung function in patients with chronic obstructive pulmonary disease (COPD) is likely due to both environmental and genetic factors. We report here a targeted high-throughput DNA sequencing approach to identify new and previously known genetic variants in a set of candidate genes for COPD.MethodsExons in 22 genes implicated in lung development as well as 61 genes and 10 genomic regions previously associated with COPD were sequenced using individual DNA samples from 68 cases with moderate or severe COPD and 66 controls matched for age, gender and smoking. Cases and controls were selected from the Obstructive Lung Disease in Northern Sweden (OLIN) studies.ResultsIn total, 37 genetic variants showed association with COPD (p < 0.05, uncorrected). Several variants previously discovered to be associated with COPD from genetic genome-wide analysis studies were replicated using our sample. Two high-risk variants were followed-up for functional characterization in a large eQTL mapping study of 1,111 human lung specimens. The C allele of a synonymous variant, rs8040868, predicting a p.(S45=) in the gene for cholinergic receptor nicotinic alpha 3 (CHRNA3) was associated with COPD (p = 8.8 x 10−3). This association remained (p = 0.003 and OR = 1.4, 95 % CI 1.1-1.7) when analysing all available cases and controls in OLIN (n = 1,534). The rs8040868 variant is in linkage disequilibrium with rs16969968 previously associated with COPD and altered expression of the CHRNA5 gene. A follow-up analysis for detection of expression quantitative trait loci revealed that rs8040868-C was found to be significantly associated with a decreased expression of the nearby gene cholinergic receptor, nicotinic, alpha 5 (CHRNA5) in lung tissue.ConclusionOur data replicate previous result suggesting CHRNA5 as a candidate gene for COPD and rs8040868 as a risk variant for the development of COPD in the Swedish population.Electronic supplementary materialThe online version of this article (doi:10.1186/s12890-016-0309-y) contains supplementary material, which is available to authorized users.

Restrictive spirometric pattern in the general adult population: Methods of defining the condition and consequences on prevalence

BackgroundAttempts have been made to use dynamic spirometry to define restrictive lung function, but the definition of a restrictive spirometric pattern (RSP) varies between studies such as BOLD and NHANES. The aim of this study was to estimate the prevalence and risk factors of RSP among adults in northern Sweden based on different definitions. MethodsIn 2008–2009 a general population sample aged 21–86y within the obstructive lung disease in northern Sweden (OLIN) studies was examined by structured interview and spirometry, and 726 subjects participated (71% of invited). The prevalence of RSP was calculated according to three different definitions based on pre-as well as post-bronchodilator spirometry:1) FVC < 80% & FEV1/FVC > 0.72) FVC < 80% & FEV1/FVC > LLN3) FVC < LLN & FEV1/FVC > LLN ResultsThe three definitions yielded RSP prevalence estimates of 10.5%, 11.2% and 9.4% respectively, when based on pre-bronchodilator values. The prevalence was lower when based on post-bronchodilator values, i.e. 7.3%, 7.9% and 6.6%. According to definition 1 and 2, the RSP prevalence increased by age, but not according to definition 3. The overlap between the definitions was substantial. When corrected for confounding factors, manual work in industry and diabetes with obesity were independently associated with an increased risk for RSP regardless of definition. ConclusionsThe prevalence of RSP was 7–11%. The prevalence estimates differed more depending on the choice of pre- compared to post-bronchodilator values than on the choice of RSP definition. RSP was, regardless of definition, independently associated with manual work in industry and diabetes with obesity.

Only severe COPD is associated with being underweight: results from a population survey.

Low body mass index (BMI) and malnutrition in chronic obstructive pulmonary disease (COPD) are associated with a poor prognosis. The prevalence of underweight, as well as overweight, in severity grades of COPD is sparsely investigated in studies of the general population and the associated patterns of risk factors are not well established. The aim of the present study was to determine the association between severity grades of airflow limitation in COPD, and both underweight and obesity when corrected for possible confounding factors.The study is based on pooled data from the OLIN (Obstructive Lung Disease in Northern Sweden) studies. Complete records with lung function, BMI and structured interview data were available from 3942 subjects (50.7% women and 49.3% men). COPD and severity grading were defined using the Global Initiative for Chronic Obstructive Lung Disease criteria. In sensitivity analyses, the lower limit of normal was used.The prevalence of underweight was 7.3% in severe COPD (grades 3 and 4) versus 2.0% in those with normal spirometry. The prevalence of obesity increased from 9.7% in grade 1, to 16.3% in grade 2 and 20.0% in severe COPD, versus 17.7% in those with normal spirometry.In adjusted analysis, of the COPD severity grades, only severe COPD was associated with underweight (OR 3.24, 95% CI 1.0004–10.5), while the COPD severity grades tended to be inversely associated with overweight.

Evaluation of a tobacco prevention programme among teenagers in Sweden

ObjectiveTo study the prevalence of tobacco use among teenagers, to evaluate a tobacco prevention programme and to study factors related to participation in the prevention programme.Design and settingPopulation-based prospective cohort...

Environmental risk factors related to the incidence of wheeze and asthma in adolescence

Asthma is common among adolescents, but there are few population-based studies on the risk factors for incident asthma and wheeze at this age group. To study risk factors for incident asthma and wheeze in adolescence. Within the Obstructive Lung Disease In Northern Sweden (OLIN) studies, a cohort of 3430 school children (age 7-8 year) was recruited in 1996. In the present study, this cohort was followed from age 12-19 year. At baseline (age 12 year), 3151 participated and skin prick tests (SPT) were performed. The cohort was resurveyed annually, and risk factors for the cumulative incidence of asthma and wheeze from age 12-19 year were analysed using multivariate Cox regression. Female sex (wheeze: HR 1.4 95%CI 1.2-1.6; asthma: HR 1.8 95%CI 1.2-2.5) and a positive SPT to cat, dog or horse at baseline (wheeze: HR 1.6 95%CI 1.2-2.1; asthma: HR 2.3 95%CI 1.4-4.0) were significantly associated with the cumulative incidence of wheeze and asthma. Increasing numbers of siblings were inversely related to the incidence of wheeze (HR 0.9 95%CI 0.8-0.97) and asthma (HR 0.8 95%CI 0.7-0.97). Parental asthma was related to the incidence of asthma (HR 1.8 95%CI 1.2-2.6) while ever smoking (HR 2.0 95%CI 1.6-2.4) and house dampness (HR 1.3 95%CI 1.1-1.6) were risk factors for the incidence of wheeze. Maternal ETS exposure increased the risk of incident asthma in non-sensitized subjects (HR 1.9 95%CI 1.0-3.7). Several environmental risk factors related to the incidence of asthma and wheeze in adolescence were identified and may be possible targets for intervention and prevention.

Passive Smoking Exposure Is Associated With Increased Risk of COPD in Never Smokers

Passive smoking, or environmental tobacco smoke (ETS), is a risk factor for lung cancer, cardiovascular disease, and childhood asthma, but a relationship with COPD has not been fully established. Our aim was to study ETS as a risk factor for COPD in never smokers. Data from three cross-sectional studies within the Obstructive Lung Disease in Northern Sweden (OLIN) database were pooled. Of the 2,182 lifelong never smokers, 2,118 completed structured interviews and spirometry of acceptable quality. COPD was defined according to the GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria using postbronchodilator spirometry. The association of COPD with ETS in single and multiple settings was calculated by multivariate logistic regression adjusting for known risk factors for COPD. COPD prevalence was associated with increased ETS exposure: 4.2% (no ETS), 8.0% (ETS ever at home), 8.3% (ETS at previous work), and 14.7% (ETS ever at home and at both previous and current work), test for trend P = .003. Exclusion of subjects aged ≥ 65 years and subjects reporting asthma yielded similar results. ETS in multiple settings, such as ever at home and at both previous and current work, was strongly associated to COPD (OR, 3.80; 95% CI, 1.29-11.2). In this population-based sample of never smokers, ETS was independently associated with COPD. The association was stronger for ETS in multiple settings. ETS in multiple settings was, after age, the strongest risk factor for COPD and comparable to personal smoking of up to 14 cigarettes/d in comparable materials. The findings strongly advocate measures against smoking in public places.

Creating a balance between breathing and viability: experiences of well-being when living with chronic obstructive pulmonary disease

To describe experiences of well-being among people with moderate to very severe chronic obstructive pulmonary disease (COPD). Living with COPD is related to a complex life situation, and quality of life (QOL) is shown to decrease because of respiratory symptoms and fatigue. However, studies describing well-being in COPD as a subjective description of QOL are rare. Ten participants with moderate to very severe COPD from the Obstructive Lung Disease in Northern Sweden (OLIN) COPD study were interviewed about their experiences of well-being. A latent qualitative content analysis was used to analyse the data. To achieve well-being despite breathlessness, the participants had to adapt to their limitations and live towards the future. They created a balance between breathing and viability by adjusting to a lifelong limitation, handling variations in illness, relying on self-capacity and accessibility to a trustful care. The participants adjusted to lifelong limitations through acceptance and replacement of former activities. They handled variations in illness by taking advantage of the good days and using emotional adaptation strategies. The participants relied on their own self-capacity, feeling that smoking cessation, physical activity and breathing fresh air increased their well-being. They requested accessibility to a trustful care and highlighted the need for continuous care relationships and access to medications. These findings can enhance health-care professionals' understanding of the possibilities for increased well-being for people living with COPD.

Vitamin D deficiency at the Arctic Circle – a study in food‐allergic adolescents and controls

At the extremes of latitude, UVB intensity is insufficient for adequate vitamin D synthesis in winter. Fatty fish, vitamin D enriched milk, margarine and eggs are main dietary sources of vitamin D. Their elimination may increase the risk of vitamin D deficiency. The aim was to assess vitamin D status in food-allergic adolescents eliminating milk, egg and/or fish compared with adolescents on normal diets. In winter, vitamin D intake was assessed by a food frequency questionnaire in 20 food-allergic adolescents and 42 controls in the population-based Obstructive Lung Disease In Northern Sweden (OLIN) cohort studies. Vitamin D supplementation was queried. Serum 25-hydroxyvitamin D [S-25(OH)D] and S-parathormone (S-PTH) levels were determined. Mean (SD) dietary vitamin D intake was 7.9 (3.6) μg/day in allergic adolescents and 7.8 (3.4) in controls (p>0.05). Mean (SD) S-25(OH)D levels in supplement consumers were 44 (18) nmol/L compared with 35 (10) in non-consumers (p=0.03). S-25(OH)D and S-PTH levels were similar in food-allergic adolescents and controls (p>0.05). Eighty-two percentage had deficient S-25(OH)D levels <50nmol/L, and none reached levels >75nmol/L. Vitamin D deficiency was as common in food-allergic adolescents as in controls although the vitamin D intake met national recommendations. Large-scale studies on the prevalence of vitamin D deficiency in this region are needed.

COPD among non-smokers – Report from the Obstructive Lung Disease in Northern Sweden (OLIN) studies

In westernized countries smoking and increasing age are the most important risk factors for COPD. Prevalence and risk factors of COPD among non-smokers are not well studied. To study the prevalence and risk factors of COPD among non-smokers and to determine the proportion of non-smokers among subjects with COPD. A random sample of 2470 subjects drawn from a population-based postal survey of 10,040 (85-88% participation) adults (aged 20-77) in Norrbotten, Sweden, were invited to structured interviews and lung function tests, and 1897 participated. COPD was classified using the fixed ratio (GOLD) definition and for comparison the lower limit of normal (LLN). The prevalence of airway obstruction was 6.9% among non-smokers and strongly age related. The prevalence of GOLD stage ≥II among non-smokers was 3.5%. Both among subjects with airway obstruction and among subjects with GOLD stage ≥II, the proportions of non-smokers were 20%. Of men with airway obstruction, 14.1% were non-smokers versus 26.8% among women. Non-smokers with GOLD stage ≥II had significantly more symptoms and higher co-morbidity than non-smokers without airway obstruction. Sex, area of domicile and exposure to environmental tobacco smoke was not significantly associated to airway obstruction among non-smokers. Using LLN for defining airway obstruction yielded a similar prevalence. The prevalence of airway obstruction among non-smokers was close to 7% and was associated with increasing age. One out of seven men with airway obstruction, defined using the fixed ratio, versus one out of four women had never smoked.