CHILDHOOD ASTHMA IN 4 REGIONS IN SCANDINAVIA - RISK-FACTORS AND AVOIDANCE EFFECTS

Background. The high and increasing prevalence of childhood asthma is a major public health issue. Various risk factors have been proposed i n local studies with different designs. Methods. We have made a questi onnaire study of the prevalence of childhood asthma, potential risk fa ctors and their relations in four regions in Scandinavia (Umea and Mal mo in Sweden, Kuopio in eastern Finland and Oslo, Norway). One urban a nd one less urbanized area were selected in each region, and a study g roup of 15 962 children aged 6-12 years was recruited. Results. The pr evalence of symptoms suggestive of asthma varied considerably between different areas (dry cough 8-19%, asthma attacks 4-8%, physician-diagn osed asthma 4-9%), as did the potential risk factors. Urban residency was generally not a risk factor. However, dry cough was common in the most traffic polluted area. Exposure to some of the risk factors, such as smoking indoors and moisture stains or moulds at home during the f irst 2 years of life, resulted in an increased risk. However, current exposure was associated with odds ratios less than one. Conclusions. O ur findings were probably due to a combination of early impact and lat er avoidance of these risk factors. The effects of some risk factors w ere found to differ significantly between regions. No overall pattern between air pollution and asthma was seen, but air pollution differed less than expected between the areas.