Abstract
The annual incidence of asthma in adults in northern Sweden has been estimated at 2.3 per thousand population. Risk factors for incident asthma among adults were studied in a case-referent study based on incident cases of asthma during 1995-1999. The healthcare providers reported suspected cases of incident asthma. After clinical examination, 309 (65% female) of 473 reported subjects were included. Inclusion criteria were a history of incident asthma (onset <12 months) and verified bronchial variability. Referents were randomly selected and stratified by age, sex and area of residence. The significant risk factors were hay fever, a family history of asthma, ex-smoking status and elevated body mass index (25.0-29.9 and > or =30). The risk factor pattern was similar for females and males, and increased body mass index was a significant risk factor for both males and females, as well as for allergic and nonallergic subjects. In conclusion, in addition to hay fever, a family history of asthma, allergic sensitisation and ex-smoking status, increased body mass index was a significant risk factor for incident asthma independent of sex and allergic status.
Highlights
The healthcare providers reported suspected cases of incident asthma
Characteristics of incident cases Bronchial variability was verified by methacholine test in 284 of the 309 cases, positive reversibility test in 11 and peak flow curve in nine
Bronchial variability was not verified during the examination, but they had documented bronchial variability from a test performed before the referral
Summary
The healthcare providers reported suspected cases of incident asthma. 309 (65% female) of 473 reported subjects were included. Inclusion criteria were a history of incident asthma (onset ,12 months) and verified bronchial variability. The significant risk factors were hay fever, a family history of asthma, ex-smoking status and elevated body mass index (25.0–29.9 and o30). The risk factor pattern was similar for females and males, and increased body mass index was a significant risk factor for both males and females, as well as for allergic and nonallergic subjects. In addition to hay fever, a family history of asthma, allergic sensitisation and exsmoking status, increased body mass index was a significant risk factor for incident asthma independent of sex and allergic status. The annual incidence of asthma is relatively high among adults and has, in northern Sweden, been estimated at 2.3 per thousand population [6]
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