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. 2012 Jul 11;7(7):e40570. doi: 10.1371/journal.pone.0040570

Table 5. Multivariable logistic regression analysis to identify risk factors for frequent exacerbation.

Variables RR 95%CI p-value
Age, per increase of 1 year 1.00 0.93–1.09 0.90
Smoking index, per increase of 1 pack-year 0.98 0.96–1.00 0.10
Body mass index, per increase of 1 kg/m2 0.89 0.70–1.12 0.34
CRP, per increase of 1 µg/ml 0.99 0.99–1.00 0.70
γ-globulin, per increase of 1 g/dL 2.07 0.17–25.1 0.56
ICS, yes/no 2.01 0.57–7.55 0.28
Tiotropium, yes/no 1.53 0.41–5.80 0.52
LABA, yes/no 1.31 0.33–5.20 0.69
%FEV1, per increase of 1% 0.99 0.94–1.02 0.49
Exacerbations in previous year, yes/no 4.43 1.20–19.6 0.025
Normal IgG antibody titer againstPorphyromonas gingivalis., yes/no 5.27 1.30–25.7 0.019

Frequent exacerbation is defined as ≥2 exacerbations per year.

RR, relative risk; CI, confidence interval; CRP, C-reactive protein; ICS, inhaled corticosteroid; LABA, long-acting β2 agonist.