Table 3

The association between change in PA prior to baseline and incident asthma in the Nord-Trøndelag Health Study, Norway, 1984–1986 to 2006–2008 (n=12 707)

Level of physical activity			Model 1*		Model 2†		Model 3‡
Level of physical activity	N	Cases	OR	95% CI	OR	95% CI	OR	95% CI
Inactive	150	9	Ref		Ref		Ref
Active survey 1 only	374	10	0.43	0.17 to 1.10	0.4	0.16 to 1.05	0.41	0.16 to 1.06
Active survey 2 only	815	25	0.50	0.23 to 1.14	0.53	0.25 to 1.23	0.53	0.24 to 1.23
Active both	11 368	404	0.58	0.31 to 1.23	0.68	0.36 to 1.45	0.66	0.35 to 1.44
Any activity	12 557	439	0.57	0.30 to 1.21	0.65	0.34 to 1.40	0.64	0.34 to 1.38

The 11-year cumulative incidence of asthma was calculated according to PA.
*Model 1: crude.
†Model 2: adjusted age, BMI, sex, smoking status, education, family history of asthma, social benefit and economic difficulties.
‡Model 3: adjusted age, BMI, sex, smoking status, education, family history of asthma, social benefit, economic difficulties and allergic rhinitis.
BMI, body mass index; n, number of observations; PA, physical activity.