Helena Backman

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

BACKGROUND 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. METHODS 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. RESULTS 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). CONCLUSIONS 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.

Low incidence and high remission of allergic sensitization among adults

BACKGROUND Prospective studies on the incidence and remission of allergic sensitization among adults are rare. OBJECTIVE We sought to assess the incidence, remission, risk factors, and prevalence of allergic sensitization in relation to aging over a 10-year period. METHODS In 1994, a sample of 664 adults (68% of invited) participated in clinical examinations, including a structured interview and skin prick tests (SPTs). The sample was randomly selected from a large questionnaire survey in Northern Sweden. In 2004, 555 subjects (93% of invited) were re-examined by using the same methods as in 1994. IgE levels were also measured in 2004. RESULTS In 1994, the prevalence of any positive SPT response was significantly related to age, with the highest prevalence (55%) in subjects aged 20 to 29 years and the lowest prevalence (26%) in subjects aged 50 to 60 years. A similar age-related prevalence was found in 2004, and sensitization to pollen and pets was most common in both years. The results of the SPTs were verified by means of specific IgE measurement. The incidence of any positive SPT response was low. Only 9 subjects had any positive SPT response (ie, a cumulative incidence of 5% over 10 years). Remission was greater (ie, 32% over 10 years). The main risk factors for allergic sensitization were young age and a family history of allergy. Having had furred animals at home during childhood was negatively related to specific IgE levels. CONCLUSION The low incidence and high remission in adulthood explain the decreasing prevalence of allergic sensitization by age. Thus the low prevalence of allergic sensitization among the elderly found in cross-sectional studies is an effect of normal aging and not primarily a birth cohort effect.

Prevalence trends in respiratory symptoms and asthma in relation to smoking - two cross-sectional studies ten years apart among adults in northern Sweden

BackgroundSmoking is considered to be the single most important preventable risk factor for respiratory symptoms. Estimating prevalence of respiratory symptoms is important since they most often precede a diagnosis of an obstructive airway disease, which places a major burden on the society. The aim of this study was to estimate prevalence trends of respiratory symptoms and asthma among Swedish adults, in relation to smoking habits. A further aim was to estimate the proportion of respiratory symptom and asthma prevalence attributable to smoking.MethodsData from two large-scale cross-sectional surveys among adults performed in northern Sweden in 1996 and 2006 were analysed. Identical methods and the same questionnaire were used in both surveys. The association between smoking, respiratory symptoms and asthma was analysed with multiple logistic regression analyses. Changes in prevalence of respiratory symptoms and asthma from 1996 to 2006 were expressed as odds ratios. Additionally, the population attributable risks of smoking were estimated.ResultsThe prevalence of most respiratory symptoms decreased significantly from 1996 to 2006. Longstanding cough decreased from 12.4 to 10.1%, sputum production from 19.0 to 15.0%, chronic productive cough from 7.3 to 6.2%, and recurrent wheeze from 13.4 to 12.0%. Any wheeze and asthmatic wheeze remained unchanged. This parallels to a decrease in smoking from 27.4 to 19.1%. In contrast, physician-diagnosed asthma increased from 9.4 to 11.6%. The patterns were similar after correction for confounders. All respiratory symptoms were highly associated with smoking, and the proportion of respiratory symptoms in the population attributed to smoking (PAR) ranged from 9.8 to 25.5%. In 2006, PAR of smoking was highest for recurrent wheeze (20.6%).ConclusionsIn conclusion, we found that respiratory symptoms, in particular symptoms common in bronchitis, decreased among adults in northern Sweden, parallel to a decrease in smoking from 1996 to 2006. In contrast, the prevalence of physician-diagnosed asthma increased during the same time-period. Up to one fourth of the respiratory symptom prevalence in the population was attributable to smoking.

Health economic costs of COPD in Sweden by disease severity – Has it changed during a ten years period?

OBJECTIVES The objectives of the presented study were to estimate societal costs of COPD in Sweden, the relationship between costs and disease severity, and possible changes in the costs during the last decade. METHODS Subjects with COPD derived from the general population in Northern Sweden were interviewed by telephone regarding their resource utilisation and productivity losses four times quarterly during 2009-10. Mean annual costs were estimated for each severity stage of COPD. RESULTS A strong relationship was found between disease severity and costs. Estimated mean annual costs per subject of mild, moderate, severe and very severe COPD amounted to 596 (SEK 5686), 3245 (SEK 30,957), 5686 (SEK 54,242), and 17,355 euros (SEK 165,569), respectively. The main cost drivers for direct costs were hospitalisations (for very severe COPD) and drugs (all other severity stages). The main cost driver for indirect costs was productivity loss due to sick-leave (for mild COPD) and early retirement (all other severity stages). Costs appeared to be lower in 2010 than in 1999 for subjects with severe and very severe COPD, but higher for those with mild and moderate COPD. CONCLUSION Our results show that costs of COPD are strongly related to disease severity, and scaling the data to the whole Swedish population indicates that the total costs in Sweden amounted to 1.5 billion euros (SEK 13.9 bn) in 2010. In addition, costs have decreased since 1999 for subjects with severe and very severe COPD, but increased for those with mild and moderate COPD.

Evaluation of the global lung function initiative 2012 reference values for spirometry in a Swedish population sample

BackgroundThe Global Lung Function Initiative 2012 (GLI) reference values are currently endorsed by several respiratory societies but evaluations of applicability for adults resident in European countries are lacking. The aim of this study was to evaluate if the GLI reference values are appropriate for an adult Caucasian Swedish population.MethodsDuring 2008–2013, clinical examinations including spirometry were performed on general population samples in northern Sweden, in which 501 healthy Caucasian non-smokers were identified. Predicted GLI reference values and Z-scores were calculated for each healthy non-smoking subject and the distributions and mean values for FEV1, FVC and the FEV1/FVC ratio were examined. The prevalence of airway obstruction among these healthy non-smokers was calculated based on the Lower Limit of normal (LLN) criterion (lower fifth percentile) for the FEV1/FVC ratio. Thus, by definition, a prevalence of 5% was expected.ResultsThe Z-scores for FEV1, FVC and FEV1/FVC were reasonably, although not perfectly, normally distributed, but not centred on zero. Both predicted FEV1 and, in particular, FVC were lower compared to the observed values in the sample. The deviations were greater among women compared to men. The prevalence of airway obstruction based on the LLN criterion for the FEV1/FVC ratio was 9.4% among women and 2.7% among men.ConclusionsThe use of the GLI reference values may produce biased prevalence estimates of airway obstruction in Sweden, especially among women. These results demonstrate the importance of validating the GLI reference values in different countries.

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

BACKGROUND 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. AIM To study the prevalence and risk factors of COPD among non-smokers and to determine the proportion of non-smokers among subjects with COPD. METHODS 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). RESULTS 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. CONCLUSION 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.

Is asthma prevalence still increasing

Increased awareness of asthma in society and altered diagnostic practices makes evaluation of data on prevalence change difficult. In most parts of the world the asthma prevalence seems to still be increasing. The increase is associated with urbanization and has been documented particularly among children and teenagers in urban areas of middle- and low-level income countries. Use of validated questionnaires has enabled comparisons of studies. Among adults there are few studies based on representative samples of the general population which allow evaluation of time trends of prevalence. This review focuses mainly on studies of asthma prevalence and symptoms among adults. Parallel with increased urbanization, we can assume that the increase in asthma prevalence in most areas of the world will continue. However, in Australia and North-West Europe studies performed, particularly among children and adolescents, indicate that the increase in asthma prevalence may now be leveling off.

Prevalence and risk factors of COPD among never-smokers in two areas of Sweden - Occupational exposure to gas, dust or fumes is an important risk factor.

BACKGROUND Although active tobacco smoking is the main risk factor for COPD, COPD is not uncommon also among never-smokers. Different study locations along with different spirometric definitions of COPD have historically yielded different prevalence estimates of the disease. AIM To study current prevalence and risk factors of COPD among never-smokers in two areas of Sweden. METHODS Data collected in 2008-2012 within the West Sweden Asthma Study and Obstructive Lung Disease in Northern Sweden Studies was pooled. The study population consisted of 1839 subjects who participated in spirometry and interviews. COPD was defined as post-bronchodilator a) FEV(1)/(F)VC < 0.7, b) FEV(1)/FVC < 0.7 and c) FEV(1)/FVC < lower limit of normal. RESULTS Of the 1839 subjects, 967 (52.6%) were never-smokers. Among the never-smoking subjects, the prevalence of COPD according to definitions a-c was 7.7%, 4.9% and 3.0%, respectively. The corresponding prevalence of GOLD grade ≥2 was 2.0%, 1.4% and 1.3%. No significant difference in prevalence between the two study areas was observed. In never-smokers, occupational exposure to gas, dust or fumes (GDF) was significantly associated with both COPD (OR 1.85, 95% CI 1.03-3.33), and GOLD ≥2 (OR 4.51, 1.72-11.9) according to definition a), after adjusting for age, educational level and exposure to passive smoking at work. CONCLUSION Depending on definition, prevalence of COPD among never-smokers was 3.0-7.7%, whereas GOLD ≥2 was present in 1.3-2.0%. Occupational exposure to GDF remained independently and significantly associated with COPD regardless of spirometric definition of the disease.

Increased prevalence of allergic asthma from 1996 to 2006 and further to 2016 : results from three population surveys

During the latter half of the 20th century, the prevalence of asthma and many other allergic diseases has increased. Information on asthma prevalence trends among adults after 2010, especially regarding studies separating allergic asthma from non‐allergic asthma, is lacking.

Reference values for spirometry - report from the Obstructive Lung Disease in Northern Sweden studies

Background Abnormal lung function is commonly identified by comparing observed spirometric values to corresponding reference values. It is recommended that such reference values for spirometry are evaluated and updated frequently. The aim of this study was to estimate new reference values for Swedish adults by fitting a multivariable regression model to a healthy non-smoking general population sample from northern Sweden. Further aims were to evaluate the external validity of the obtained reference values on a contemporary sample from south-western Sweden, and to compare them to the Global Lung Function Initiative (GLI) reference values. Method Sex-specific multivariable linear regression models were fitted to the spirometric data of n=501 healthy non-smoking adults aged 22–91 years, with age and height as predictors. The models were extended to allow the scatter around the outcome variable to depend on age, and age-dependent spline functions were incorporated into the models to provide a smooth fit over the entire age range. Mean values and lower limits of normal, defined as the lower 5th percentiles, were derived. Result This modelling approach resulted in unbiased estimates of the spirometric outcomes, and the obtained estimates were appropriate not only for the northern Sweden sample but also for the south-western Sweden sample. On average, the GLI reference values for forced expiratory volume in one second (FEV1) and, in particular, forced expiratory vital capacity (FVC) were lower than both the observed values and the new reference values, but higher for the FEV1/FVC ratio. Conclusion The evaluation based on the sample of healthy non-smokers from northern Sweden show that the Obstructive Lung Disease in Northern Sweden reference values are valid. Furthermore, the evaluation based on the south-western Sweden sample indicates a high external validity. The comparison with GLI brought further evidence to the consensus that, when available, appropriate local population-specific reference values may be preferred.