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Table 3 Unadjusted and adjusted hazard ratios for COPD exacerbations according to IgG subclass levels in the MACRO and STATCOPE cohorts

From: Serum IgG subclass levels and risk of exacerbations and hospitalizations in patients with COPD

MACRO – Time to first Exacerbation
IgGa Univariate analysis Multivariate analysisb
Hazard Ratio (95% CI) P Hazard Ratio (95% CI) P
IgG1 1.43 (1.23–1.67) < 0.001 1.30 (1.10–1.54) 0.002
IgG2 1.29 (1.15–1.45) < 0.001 1.19 (1.05–1.35) 0.006
IgG3 0.99 (0.88–1.11) 0.84 0.95 (0.85–1.07) 0.39
IgG4 1.09 (1.02–1.17) 0.009 1.05 (0.98–1.13) 0.17
STATCOPE – Time to first Exacerbation
IgGa Hazard Ratio (95% CI) P Hazard Ratio (95% CI) P
IgG1 1.45 (1.20–1.75) < 0.001 1.25 (1.02–1.54) 0.035
IgG2 1.32 (1.15–1.52) < 0.001 1.17 (1.01–1.36) 0.046
IgG3 1.10 (0.98–1.25) 0.11 0.99 (0.87–1.13) 0.90
IgG4 1.01 (0.94–1.08) 0.76 0.96 (0.89–1.04) 0.33
  1. aIgG subclass levels expressed using a negative-log transformation (base 2), with one-unit increase on this log scale being equivalent to a 50% decrease of IgG subclass levels. bAdjusted hazard ratios for IgG levels were calculated using a Cox Proportional Hazards model with adjustments for the following covariates: study drug (azithromycin vs. placebo in MACRO - First cohort; simvastatin vs. placebo in STATCOPE - Replication cohort), age, gender, ethnicity (Caucasian vs. Non-Caucasian), FEV1 (% of predicted values), smoking status (current vs. former smokers), oxygen dependence, inhaled corticosteroid use, and treatment with systemic steroids in previous year. Legend: 95% CI = 95% Confidence Interval