Parallel gradients in FENO and in the prevalences of asthma and atopy in adult general populations of Sweden, Finland and Estonia - A Nordic EpiLung study.

The prevalence of asthma is higher in Sweden and Finland than in neighbouring eastern countries including Estonia. Corresponding difference in bronchial eosinophilic inflammation could be studied by FENO measurements. We aimed to compare FENO in adult general populations of Sweden, Finland, and Estonia, to test the plausibility of the west-east disparity hypothesis of allergic diseases. We conducted clinical interviews (N = 2658) with participants randomly selected from the general populations in Sweden (Stockholm and Örebro), Finland (Helsinki), and Estonia (Narva and Saaremaa), and performed FENO (n = 1498) and skin prick tests (SPT) in 1997-2003. The median (interquartile range) of FENO (ppb) was 15.5 (9.3) in Sweden, 15.4 (13.6) in Finland and 12.5 (9.6) in Estonia. We found the lowest median FENO values in the Estonian centres Saaremaa 13.1 (9.5) and Narva 11.8 (8.6). In the pooled population, asthma was associated with FENO ≥25 ppb, odds ratio (OR) 3.91 (95% confidence intervals: 2.29-6.32) after adjusting for SPT result, smoking, gender and study centre. A positive SPT test increased the likelihood of asthma OR 3.19 (2.02-5.11). Compared to Saaremaa, the likelihood of having asthma was higher in Helsinki OR 2.40 (1.04-6.02), Narva OR 2.45 (1.05-6.19), Örebro OR 3.38 (1.59-8.09), and Stockholm OR 5.54 (2.18-14.79). There was a higher prevalence of asthma and allergic airway inflammation in adult general populations of Sweden and Finland compared to those of Estonia. Atopy and elevated FENO level were independently associated with an increased risk of asthma. In conclusion, the findings support the earlier west-east disparity hypothesis of allergic diseases.

High prevalence of rhinitis symptoms without allergic sensitization in Estonia and Finland.

OBJECTIVES: Allergic rhinitis and atopy are more common in urban than rural environments. Non-allergic rhinitis has not been studied to a great extent. We aimed to assess the relationship of rhinitis symptoms with different profiles of allergic sensitization, comparing this in rural and urban environments. METHODS: The study population consisted of population-based cohorts of adults aged 26-60 from Helsinki, Finland, and rural Saaremaa and urban Tallinn, Estonia. We compared the results of a structured interview and skin prick tests and assessed the risk factors for rhinitis. RESULTS: The prevalence of rhinitis symptoms with atopy was 32.7% in Helsinki, 20.8% in Tallinn, and 12.5% in Saaremaa (p<0.001). Rhinitis symptoms without atopy were found in 26.4%, 29.8%, and 29.3% (p=n.s.), respectively. In Helsinki, 87.3% of participants with atopy identified symptoms as allergic, compared to 57.0% in Tallinn and 47.5% in Saaremaa. Childhood in the countryside (OR 0.63), family history of allergic rhinitis (OR 1.89), and polysensitization (OR 15.99) were significantly associated with rhinitis symptoms with atopy in a multivariate logistic regression model. The most common sensitizers were pollens and animals in Helsinki and mites in Estonia. Exposure to environmental tobacco smoke (OR 1.50) and family history of allergic rhinitis (OR 1.70) were associated with rhinitis symptoms without atopy. CONCLUSION: Rhinitis symptoms without allergic sensitization were common in both Finland and Estonia and were associated with environmental tobacco smoke. Family history of allergic rhinitis predisposed to rhinitis symptoms irrespective of atopy status.

Dose-dependent association of smoking and bronchial hyperresponsiveness.

Our aim was to study the association of smoking habits and environmental tobacco smoke (ETS) exposure with bronchial hyperresponsiveness (BHR). A random sample of 292 adults was examined using a structured interview, spirometry, skin prick tests, exhaled nitric oxide fraction (FeNO) and bronchial histamine challenge. A large majority of subjects with BHR were smokers or ex-smokers. Starting to smoke before 20 years of age was significantly associated with BHR, as was current smoking, quantity of smoking and ETS exposure. The severity of BHR increased significantly with increasing pack-years of exposure (p<0.001). Current smokers with decreased lung function were at a particularly high risk of BHR. Impaired forced expiratory volume in 1 s and mean maximal expiratory flow were independent determinants for more severe BHR, regardless of age. In multivariate analysis, smoking remained an independent determinant for BHR after adjustment for impaired lung function and other covariates: ≥15 pack-years yielded an odds ratio of 3.00 (95% CI 1.33-6.76) for BHR. The association between BHR and FeNO was dependent on smoking habits. The results indicate that smoking is a significant risk factor for BHR, with a dose-dependent pattern, and that the severity of BHR increases with pack-years. The findings strongly suggest assessment of smoking habits in subjects with BHR.

Bronchial hyperresponsiveness in an adult population in Helsinki: decreased FEV1 , the main determinant.

INTRODUCTION: Bronchial hyperresponsiveness (BHR) elevates the risk for development of respiratory symptoms and accelerates the decline in forced expiratory volume in the first second (FEV1 ). We thus aimed to assess the prevalence, determinants and quantity of BHR in Helsinki. OBJECTIVES: This study involved 292 randomly selected subjects age 26-66years, women comprising 58%. METHODS: Following a structured interview, a spirometry, a bronchodilation test, and a skin-prick test, we assessed a bronchial challenge test with inhaled histamine using a dosimetric tidal breathing method. Results included the provocative dose inducing a decrease in FEV1 by 15% (PD15 FEV1 ) and the dose-response slope. For statistical risk factor-analyses, the severity of BHR was considered; PD15 values ≤1.6mg (BHR) and ≤0.4mg [moderate or severe BHR (BHRms )] served as cut-off levels. RESULTS: BHR presented in 21.2% and BHRms in 6.2% of the subjects. FEV1<80% of predicted [odds ratio (OR) 4.09], airway obstruction (FEV1 /forced vital capacity<88% of predicted) (OR 4.33) and history of respiratory infection at age <5 (OR 2.65) yielded an increased risk for BHR as ORs in multivariate analysis. For BHRms , the determinants were decreased FEV1 below 80% of predicted (OR 27.18) and airway obstruction (OR 6.16). Respiratory symptoms and asthma medication showed a significant association with BHR. CONCLUSIONS: Of the adult population of Helsinki, 21% showed BHR to inhaled histamine. The main determinants were decreased FEV1 and airway obstruction. Quantitative assessment of BHR by different cut-off levels provides a tool for characterization of phenotypes of airway disorders in epidemiologic and clinical studies.

Bronchial hyperresponsiveness in a population of north Finland with no previous diagnosis of asthma or chronic bronchitis assessed with histamine and methacholine tests.

OBJECTIVES: To assess the prevalence of bronchial hyperresponsiveness (BHR) in a population of north Finland among subjects with no previous diagnosis of asthma or chronic bronchitis by using histamine and methacholine challenges. The agreement between the methods was also evaluated. STUDY DESIGN: An epidemiological study assessing the prevalence of BHR measured with 2 direct dosimetric challenge methods. METHODS; Seventy-nine randomly selected subjects (21-73 years) were studied; 67% had respiratory or allergic symptoms. The baseline spirometry was normal or showed mild obstruction. Bronchial challenges to methacholine and histamine were performed on each subject in a randomized order. Provocative doses inducing the decrease of FEV1 by 15% and 20% (PD15FEV1 and PD20FEV1) and dose response ratios (DDR) were calculated for both tests. RESULTS; BHR with the methacholine test (PD20FEV1 < or = 2.6 mg) was found in 20% and with the histamine test (PD15FEV1 < or = 1.6 mg) in 28% of subjects; the agreement was 80% (kappa 0.45; 95% CI 0.23-0.68). In staging the severity of BHR the methods had a good agreement (weighted kappa 0.64; CI 95% 0.46-0.82). Prevalence of BHR fulfilling the criteria of the both methods was 14%. CONCLUSIONS: The findings suggest that the prevalence of BHR in the population of north Finland with no previous diagnosis of asthma or chronic bronchitis is at least 14%, probably around 20%, assessed by histamine and methacholine challenge methods. The methods have a good agreement to be used for classifying the severity of BHR.