Prevalence, age at onset, and risk factors of self-reported asthma among Swedish adolescent elite cross-country skiers.

The objective of the study was to compare the prevalence of self-reported physician-diagnosed asthma and age at asthma onset between Swedish adolescent elite skiers and a reference group and to assess risk factors associated with asthma. Postal questionnaires were sent to 253 pupils at the Swedish National Elite Sport Schools for cross-country skiing, biathlon, and ski-orienteering ("skiers") and a random sample of 500 adolescents aged 16-20, matched for sport school municipalities ("reference"). The response rate was 96% among the skiers and 48% in the reference group. The proportion of participants with self-reported physician-diagnosed asthma was higher among skiers than in the reference group (27 vs 19%, P=.046). Female skiers reported a higher prevalence of physician-diagnosed asthma compared to male skiers (34 vs 20%, P=.021). The median age at asthma onset was higher among skiers (12.0 vs 8.0 years; P<.001). Female sex, family history of asthma, nasal allergy, and being a skier were risk factors associated with self-reported physician-diagnosed asthma. Swedish adolescent elite cross-country skiers have a higher asthma prevalence and later age at asthma onset compared to a reference population. Being an adolescent, elite skier is an independent risk factor associated with asthma.