To examine the incidence of allergic rhinoconjunctivitis and asthma, and to assess allergic rhinoconjunctivitis as a risk factor for incident asthma, we performed a 11-year follow-up postal survey.
The original study population was a random population sample of 8000 inhabitants of Helsinki aged 20-69 years in 1996. Participants in the first postal questionnaire survey, 6062 subjects, were invited to this follow-up study, and provided 4302 (78%) answers out of 5484 traced subjects in 2007.
Cumulative incidence of asthma from 1996 to 2007 was 4.0% corresponding to an annual incidence rate of 3.7/1000/year. After exclusion of those with asthma medication or physician-diagnosed chronic bronchitis or COPD at baseline in 1996, the cumulative incidence decreased to 3.5% (incidence rate 3.2/1000/year), and further to 2.7% (2.5/1000/year) when also those reporting recurrent wheeze or shortness of breath during the last year in 1996 were omitted from the population at risk. Remission of asthma occurred in 43 subjects and was 16.9% over 11 years. Cumulative 11-year incidence of allergic rhinoconjunctivitis was 16.9% corresponding to 16.8/1000/year, and cumulative remission was 18.1%. Incidence of allergic rhinoconjunctivitis was significantly lower among those who had lived in the countryside or on a farm during the first 5 years of life, but this was not true for asthma. In multivariate analysis, farm living during the first 5 years of life was protective for the development of allergic rhinoconjunctivitis, OR 0.75 (95%CI 0.57-0.99). Allergic rhinoconjunctivitis was a significant independent risk factor for incident asthma, OR 2.15 (95%CI 1.54-3.02). In the cohort, the prevalence of rhinoconjunctivitis increased from 38.0% in 1996 to 40.9% in 2007, physician-diagnosed asthma from 6.8% to 9.4%, while current smoking decreased from 31.3% to 23.3%.
Incidence of allergic rhinoconjunctivitis was higher than in earlier studies, while asthma incidence remained on similar level, both being significantly higher in women. Allergic rhinoconjunctivitis doubled the risk for incident asthma.
Population-based studies on aspirin-intolerant asthma (AIA) are very few, and no previous population study has investigated risk factors for the condition.
To investigate the prevalence and risk factors of AIA in the general population.
A questionnaire on respiratory health was mailed to 30,000 randomly selected subjects aged 16-75 years in West Sweden, 29,218 could be traced and 18,087 (62%) responded. The questionnaire included questions on asthma, respiratory symptoms, aspirin-induced dyspnoea and possible determinants.
The prevalence of AIA was 0.5%, 0.3% in men and 0.6% in women (P = 0.014). Sick leave, emergency visits due to asthma and all investigated lower respiratory symptoms were more common in AIA than in aspirin-tolerant asthma (ATA). Obesity was a strong risk factor for AIA (BMI > 35: odds ratio (OR) 12.1; 95% CI 2.49-58.5), and there was a dose-response relationship between increasing body mass index (BMI) and risk of AIA. Obesity, airborne occupational exposure and visible mould at home were considerably stronger risk factors for AIA than for ATA. Current smoking was a risk factor for AIA (OR 2.55; 95% CI 1.47-4.42), but not ATA.
Aspirin-intolerant asthma identified in the general population was associated with a high burden of symptoms, uncontrolled disease and a high morbidity. Increasing BMI increased the risk of AIA in a dose-response manner. A number of risk factors, including obesity and current smoking, were considerably stronger for AIA than for ATA.
BACKGROUND: Childhood is the most important age for asthma development. Recent reports indicate that the prevalence of asthma in children has plateaued after having increased for decades. AIMS: To study prevalence and risk factor patterns of asthma by age and by time. METHODS: In 1996, all children in grade 1-2 (age 7-8) in three cities in Northern Sweden were invited to an expanded International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. A total of 3430 children (97%) participated yearly until 2000 (age 11-12). A subset (n = 2454) was invited to skin-prick testing in 1996 and 2000 with 88% and 90% participation. In 2006, another cohort (n = 2704) was identified and studied by identical methods with 96% participation. A total of 1700 children (90% of invited) were skin-prick tested. RESULTS AND COMMENTS: From age 7-8 to 11-12, the prevalence of physician-diagnosed asthma increased, 5.7%-7.7% (P
As a first step in an intervention study of asthma and allergic diseases among school children, a cross-sectional study was performed during Winter 1996 in three towns (Kiruna, Luleå and Piteå) in the northernmost province of Sweden, Norrbotten. The cross-sectional study aimed to measure the prevalence of asthma, type-1 allergy and allergic diseases in order to make it possible to measure the incidence of the diseases, conditions and symptoms related to the diseases. Another aim was to perform a screening for possible risk factors. All children enrolled in the first and second classes at school, 7 and 8 years old, were invited to take part in this study. The ISAAC questionnaire with added questions about symptoms, morbidity, heredity and environment was distributed by the schools to the parents. The response rate was 97%, and 3431 completed questionnaires were returned. The children in two of the municipalities were also invited to skin test, and 2149 (88%) were tested with 10 common airborne allergens. The results showed that 7% of the children were currently using or had used asthma medicines during the last 12 months. Six percent had asthma diagnosed by a physician, and 4% were using inhaled corticosteroids. The prevalence of wheezing during the last 12 months was 12%, rhinitis without colds 14%, and eczema 27%, while 21% had a positive skin test. The respiratory symptoms and conditions were significantly greater in boys and, further, they were most prevalent in Kiruna in the very north, though not significantly. Type-1 allergy and asthma had different risk factor patterns. The main risk factors for asthma were a family history of asthma (OR = 3.2) followed by past or present house dampness (OR = 1.9), male sex (OR = 1.7) and a smoking mother (OR = 1.6). In Kiruna, when none of these three risk factors were present, none of the children had asthma, but when all three were present, 38% of these children were using asthma medicines.
Krefting Research Centre / Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. firstname.lastname@example.org
The harmful effects of tobacco smoke on human health, including respiratory health, are extensive and well documented. Previous data on the effect of smoking on rhinitis and allergic sensitization are inconsistent. We sought to investigate how smoking correlates with prevalence of allergic and chronic rhinitis among adults in Sweden.
The study population comprised 27 879 subjects derived from three large randomly selected cross-sectional population surveys conducted in Sweden between 2006 and 2008. The same postal questionnaire on respiratory health was used in the three surveys, containing questions about obstructive respiratory diseases, rhinitis, respiratory symptoms and possible determinants of disease, including smoking habits. A random sample from one of the cohorts underwent a clinical examination including skin prick testing.
Smoking was associated with a high prevalence of chronic rhinitis in both men and women and a low prevalence of allergic rhinitis in men. These associations were dose dependent and remained when adjusted for a number of possible confounders in multiple logistic regression analysis. Prevalence of chronic rhinitis was lowest in nonsmokers and highest in very heavy smokers (18.5% vs 34.5%, P
Exacerbations are the key drivers in the costs of chronic obstructive pulmonary disease (COPD). The objective was to examine the costs of COPD exacerbations in relation to differing degrees of severity of exacerbations and of COPD. We identified 202 subjects with COPD, defined according to the BTS and ERS criteria. Exacerbations were divided into mild (self-managed), mild/moderate (telephone contact with a health-care centre and/or the use of antibiotics/systemic corticosteroids), moderate (health-care centre visits) and severe (emergency care visit or hospital admission). Exacerbations were identified by sending the subjects a letter inquiring whether they had any additional respiratory problems or influenza the previous winter. At least one exacerbation was reported by 61 subjects, who were then interviewed about resource use for these events. The average health-care costs per exacerbation were SEK 120 (95% C=39-246), SEK 354 (252-475), SEK 2111 (1673-2612) and SEK 21852 (14436-29825) for mild, mild/moderate, moderate and severe exacerbations, respectively. Subjects with impaired lung function experienced more severe exacerbations, which was also reflected in the cost of exacerbations per severity of the disease during the 4 1/2 month study period (ranging from SEK 224 for mild to SEK 13708 for severe cases, median SEK 940). Exacerbations account for 35-45% of the total per capita health-care costs for COPD. In conclusion, costs varied considerably with the severity of the exacerbation as well as with the severity of COPD. The prevention of moderate-to-severe exacerbations could be very cost-effective and improve the quality of life.
The large increase in asthma prevalence continues in several, but not all areas. Despite the individual risk factors that have been identified, the reasons for the observed trends in prevalence are largely unknown.
This study sought to characterize what trends in risk factors accompanied trends in asthma prevalence.
Two population-based cohorts of 7- to 8-year-old children from the same Swedish study areas examined by expanded International Study of Asthma and Allergy in Childhood questionnaires were compared 10 years apart. In 1996 and 2006, 3430 (97% participation) and 2585 (96% participation) questionnaires were completed, respectively. A subset was skin-prick-tested: in 1996 and 2006, 2148 (88% participation) and 1700 (90% participation) children, respectively. The adjusted population-attributable fraction (aPAF) was calculated using the prevalence and multivariate odds ratio of each risk factor.
The prevalence of current asthma and wheeze was similar in 1996 and 2006. Allergic sensitization, however, increased from 21% to 30%. The prevalence of parental asthma increased from 17% to 24%, while respiratory infections and maternal smoking decreased (60% to 29% and 32% to 16%, respectively). The aPAFs of non-environmental risk factors for current asthma increased in 1996-2006: allergic sensitization from 35% to 41%, parental asthma from 27% to 45% and male sex from 20% to 25%. Conversely, the aPAFs of environmental risk factors decreased: respiratory infections from 36% to 32% and damp home and maternal smoking from 14% and 19%, respectively, to near zero in 2006.
From 1996 to 2006, the non-environmental risk factors parental asthma, allergic sensitization and male sex had an increasing or constant importance for current asthma in 7- to 8-year-old children. The importance of the environmental exposures damp home, respiratory infections and maternal smoking decreased. This counterbalancing in risk factors may explain the level of prevalence of current asthma.
We aimed to assess the prevalence of allergic sensitization and multiple sensitization, risk factors, and the clinical impact of being sensitized in the adult population of Helsinki, Finland.
As a part of the FinEsS study, a population-based random sample of 498 adults aged 26-60 years were tested for 15 common aeroallergens with skin prick tests (SPTs) and interviewed on respiratory symptoms and diseases, including respiratory irritants and childhood environment.
The prevalence of at least one positive prick test was 46.9%. A large difference by age was found: 56.8% were sensitized among those aged 26-39 years, 49.2% in the age group 40-49 years, and 35.6% in the age group 50-60 years (P
BACKGROUND: A cross-sectional study was performed among 78-year-old schoolchildren during the winter of 1996 in three municipalities in the most northern province of Sweden, Norrbotten. The study was the starting point of a longitudinal study of asthma, rhinitis, eczema, and type-1 allergy, and provided data on prevalence and risk factors for these conditions. The aim of the present study was to validate the classification of asthma based on a parental questionnaire, and to examine risk factors for atopic and nonatopic asthma. METHODS: The ISAAC questionnaire with additional questions was distributed by the schools to the parents. The response rate was 97%, and 3431 completed questionnaires were returned. The children in Kiruna and Luleå were also invited to be skin tested, and 2149 (88%) were tested with 10 common airborne allergens. A structured interview was administered by pediatricians in stratified samples of the children to test the validity of the diagnosis of asthma based on the questionnaire. RESULTS: After the validation study, the prevalence of "ever asthma" was estimated to be 8.0%. The specificity of the question, "Has your child been diagnosed as having asthma by a physician?", was high, >99%, while the sensitivity was around 70%. The strongest risk factor for "ever asthma" was a positive skin test (OR 3.9). Risk factors for asthma in the asthmatics who were not sensitized were family history of asthma, OR 3.6; breast-feeding less than 3 months, OR 1.8; past or present dampness at home, OR 1.8; smoking mother, OR 1.7; and male sex, OR 1.6. Among the sensitized asthmatics, only a family history of asthma was a significant risk factor (OR 3.0), while breast-feeding less than 3 months was not associated with an increased risk (OR 1.0). A synergistic effect between genetic and environmental factors was found especially in the nonatopic asthmatics; the children with a family history of asthma who had a smoking mother and past or present dampness at home had an OR for "ever asthma" of 13. CONCLUSIONS: Different risk-factor patterns were found for asthma and type-1 allergy. In addition, the risk factors for atopic or allergic asthma diverged from those for nonatopic asthma.
In contrast to asthma and rhinitis, few studies among adults investigating the prevalence and risk factors of eczema have been published.
To investigate the prevalence and risk factors of eczema among adults in West Sweden. A further aim was to study the associations between asthma, rhinitis and eczema.
A questionnaire on respiratory health was mailed in 2008 to 30,000 randomly selected subjects in West Sweden aged 16-75 years; 62% responded. The questionnaire included questions about eczema, respiratory symptoms and diseases and their possible determinants. A subgroup of 669 subjects underwent skin prick testing against common airborne allergens.
'Eczema ever' was reported by 40·7% and 'current eczema' by 11·5%. Both conditions were significantly more common among women. The prevalence decreased with increasing age. The coexistence of both asthma and rhinitis with eczema was common. The main risk factors were family history of allergy and asthma. The dominant environmental risk factor was occupational exposure to gas, dust or fumes. Smoking increased the risk. Eczema was associated with urbanization, while growing up on a farm was associated with a decreased risk. Added one by one to the multivariate model, asthma, allergic rhinitis and any positive skin prick test were associated with eczema.
Eczema among adults is a common disease with more women than men having and having had eczema. Eczema is associated with other atopic diseases and with airway symptoms. Hereditary factors and exposure to gas, dust and fumes are associated with eczema.