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.

Impacts of cold climate on human heat balance, performance and health in circumpolar areas.

In circumpolar areas the climate remains cool or thermoneutral during the majority of the days of the year spite of global warming. Therefore, health consequences related to cold exposure represent also in the future the majority of climate-related adverse health effects. Hot summers may be an exception. At ambient temperatures below +10 - +12 degrees C, humans experience cold stress of varying degree. Man can compensate a 10 degrees C change in ambient temperature by changing metabolic heat production by 30-40 W m(-2) or by wearing an additional/taking off ca. 0.4 clo units (corresponding to one thick clothing layer). Cold ambient temperature may be a risk for human health and cause varying levels of performance limitations. The impacts of cold exposure on health and wellbeing cause a burden to many societies in terms of lowered productivity and higher costs related to health care systems as well as public health planning and management. In order to provide preventive and protective public health actions for cold-induced adverse health effects, it is important to recognize cold related injuries, illnesses and symptoms and their turn-up temperatures, and to identify the most at-risk population subgroups and factors that increase or decrease the health risks posed by cold ambient temperatures. The majority of cold-related harmful health impacts can be prevented or managed by correct preventive and protective actions. Rapid unpredictable changes are more difficult to compensate because of lack of experience (affecting attitude and skills), preparedness (vehicles, garments, supplies, logistics etc.) and/or acclimatization.

Spirometry values in adults in northern Finland.

OBJECTIVES: If reference values do not accurately reflect the distribution of lung function in the population, the interpretation of spirometry results may be incorrect. Differences in lung function exist between populations, which supports the use of local reference values. In Finland, the national reference values for spirometry are currently in use. The aim of this study was to assess the correlation between measured spirometric values from healthy adults and the reference values used in Finland. METHODS: In the present population-based study, spirometry results were assessed in healthy adults aged 21 to 70 years in northern Finland. After exclusions for any chronic pulmonary disease or symptom, 206 men and 215 women remained in the group. We calculated regression equations for spirometric reference values in adults and compared these with European recommendations, and with the reference values currently used in Finland. RESULTS: These comparisons revealed large differences. The linear models do not take into account the physiological changes in both young and old adults and, thus, the reference values calculated according to the European recommendations differed from the real measured results at both ends of the 20- to 70-year age scale. Moreover, values from the logarithmic Finnish reference equations also diverged from our measurements; the differences were largest in subjects younger than 30, and in elderly men. CONCLUSION: Differences between populations and reference equations make international comparisons difficult, and divergence between reference values and real results may lead to incorrect clinical interpretation.

Does living in a cold climate or recreational skiing increase the risk for obstructive respiratory diseases or symptoms?

OBJECTIVES: Respiratory symptoms and obstructive pulmonary diseases experienced during exercise and in cold weather were analysed in a large postal questionnaire study of a general adult population living in a cold climate. The aim of this study was to assess the prevalence of shortness of breath (SOB) during exercise, or in cold weather, and to find out if the risks (odds ratio=OR) for asthma, chronic bronchitis, or SOB during exercise, or in cold weather, were affected by recreational cross-country skiing, or by outdoor work in a cold climate. RESULTS: Of the 7937 invited persons, 84% responded; 876 of them were outdoor workers and 1497 were recreational cross-country skiers. Of the non-smoking responders, asthmatic subjects had the highest prevalence of SOB during exercise in cold weather (78%-82%), but allergic and bronchitic persons also had significantly higher prevalence rates (22%-38% and 27%-59%, respectively) than healthy persons (10%-19%). In all categories, the prevalence of SOB was significantly higher among current smokers than among ex- or non-smokers. Risk factor analysis revealed increased risks for respiratory conditions among those who had a family history of obstructive airway disease, or allergy. Skiers did not have a significantly increased risk for asthma, or respiratory symptoms. Among outdoor workers the risk for SOB during exercise in cold weather, OR 1.23 (CI 1.03-1.47), and for chronic bronchitis, OR 1.77 (CI 1.21-2.60), was higher than among indoor workers. CONCLUSIONS: In conclusion, the risk for chronic bronchitis and bronchitic symptoms was elevated among outdoor workers, but not among regular recreational cross-country skiers, and the risk for asthma was not significantly elevated by regular exercising, or by working in a cold climate.

Respiratory symptoms and asthma in relation to cold climate, inhaled allergens, and irritants: a comparison between northern and southern Finland.

We have compared data from northern and southern Finland in a large epidemiological survey on respiratory conditions. The aim was to compare the prevalence of respiratory symptoms, asthma, and chronic bronchitis in northern and southern Finland. The study was a part of comparative studies in Finland, Estonia, and Sweden, the FinEsS studies. Data from a postal survey on subjects aged 20-69 was analyzed. Participation rate was 84% of 7937 invited in Lapland in the north, and 77% of 7877 in Helsinki in the south. Physician-diagnosed asthma was reported by 5.6% in Helsinki, and by 5.5% in Lapland. Symptoms common in asthma were also equally prevalent in the two areas. Hay fever was significantly more common in Helsinki, 36% vs. 26% (p < 0.001). The prevalence for physician-diagnosed chronic bronchitis was not significantly higher in Helsinki (3.4%) than in Lapland (2.9%). Those working outdoors reported more bronchitic symptoms than people working indoors (p < 0.05). Respiratory symptoms provoked by pollen or animal dander were more common in Helsinki, while symptoms provoked by inhaled irritants or cold weather conditions were more prevalent in Lapland. Current smoking was equally prevalent: 37% in Lapland and 38% in Helsinki. Risk factor analysis showed an elevated risk for chronic productive cough for living in Helsinki (OR 1.32), however, increasing age and current smoking were the strongest risk factors. In conclusion, prevalence of asthma and asthma-related symptoms was similar in southern and northern Finland, but chronic bronchitis and bronchitic symptoms were more common in Helsinki, and the highest prevalence was found among current smokers working outdoors. Respiratory symptoms in cold weather were more prevalent in the north, while hay fever and respiratory symptoms provoked by allergens were more common in the south. The results support the view that environmental factors have a substantial effect on respiratory symptoms, but less effect on the prevalence of asthma.