. Author manuscript; available in PMC: 2014 Feb 1.

Published in final edited form as: J Allergy Clin Immunol. 2013 Feb;131(2):361–368.e11. doi: 10.1016/j.jaci.2012.11.036

Table II.

Asthma age of onset, lung structure and function

	≤ 18 years n=217	19 to 45 years n=102	> 45 years n=127	P-value
FEV₁ (ml)	−365 (−419 to −310) ^***	−343 (−420 to −266) ^***	−359 (−428 to −289) ^***	< 0.001
Single airway lumen diameter (mm)	−0.39 (−0.58 to −0.2) ^***	−0.34 (−0.61 to −0.07) ^*	−0.52 (−0.76 to −0.28) ^***	< 0.001
Single airway wall thickness (mm)	0.01 (−0.01 to 0.04)	0.02 (−0.02 to 0.05)	−0.02 (−0.06 to 0.009)	0.06
% LAA (%)	1.69 (0.09 to 3.29) ^*	4.30 (2.00 to 6.59) ^***	3.52 (1.45 to 5.58) ^***	< 0.001

Results represent the mean difference compared to participants without asthma from linear regression models adjusted for age, sex, height, height², race/ethnicity, smoking status, pack-years, pipe-years, urine cotinine, household ETS, education, body mass index, waist circumference, occupational exposures, particulate matter exposure. Lung structure models (lumen diameter, wall thickness and %LAA) were additionally adjusted for tube current in milliamperes and CT scanner type. The %LAA model was additionally adjusted for family history of emphysema. P-values represent the −2 log likelihood test for overall significance among asthma age of onset subgroups vs. participants without asthma.

Where significant overall, subgroups were tested individually, with p < 0.001 = *** and p < 0.05 = *.