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. Author manuscript; available in PMC: 2013 Jul 22.
Published in final edited form as: Genet Epidemiol. 2011 Feb;35(2):93–101. doi: 10.1002/gepi.20560

TABLE II.

Relationship between principal components of gene expression and relevant demographic and clinical characteristics in the CAMP cohort

Covariate Association P-value
PC1 PC2 PC3 PC4
Discrete variablesa
 Race 1.61 × 10−8 0.03 0.40 0.60
 Gender 0.24 0.11 0.04 0.48
 Clinic 1.1 × 10−6 2 × 10−16 0.07 0.02
 Active smoking history 0.007 0.61 0.08 0.88
 Asthma medication use
  Inhaled corticosteroids 0.71 0.05 0.77 0.27
  Long-acting beta agonists 0.50 0.98 0.60 0.64
Continuous variables
 Age 0.96 0.62 0.76 0.88
 Height 0.21 0.97 0.32 0.32
 Pre-bronchodilator FEV1 0.71 0.51 0.07 0.03
 Immunoglobulin E (IgE level) 0.22 0.74 0.57 0.01

FEV1, forced expiratory volume in one second; IgE, immunoglobulin E.

a

Discrete variables tested by two-sided t-test or ANOVA. Continuous variables tested by Spearman’s correlation.