Table 2.

Multivariable analysis of IGF-1 and asthma by smoking status

	Current smokers (n=29,337)	Never smoker and former smokers with < 10 pack-year cigarette smoking (n=214,907)
IGF-1 quartile (nmol/L)	Odds Ratio (95% Confidence Interval)
Q1 (< 17.8)	1.0	1.0
Q2 (17.8– < 21.5)	0.86 (0.78–0.95)*	0.95 (0.91–0.98)*
Q3 (21.5– < 25.0)	0.80 (0.72–0.89)*	0.92 (0.88–0.95)*
Q4 (≥ 25.0)	0.77 (0.69–0.86)*†	0.89 (0.85–0.92)*†

Abbreviation: IGF-1, insulin-growth like factor 1

All models adjusted for age, sex, ethnicity, annual household income, body mass index, packyears of cigarette smoking (in current smokers), the season of the examination, the time of the day when the examination was performed, serum level of glycated hemoglobin A1c, and C-reactive protein.

^*P <0.01

^†P for trend <0.05