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Table 5 Mutually adjusted risk ratios (RRs)* for the association between CB and each potential predictor

From: Diverging trends of chronic bronchitis and smoking habits between 1998 and 2010

 

RR [95% CI]

 
 

ISAYA (1998/2000)

GEIRD (2007/2010)

p-value for heterogeneity

Gender (female vs male)

1.17 [1.09−1.27]

1.11 [1.00−1.22]

0.721

Smoking habits (vs never smoking):

   

 Past light smoking

1.40 [1.21−1.62]

1.03 [0.86−1.23]

0.015

 Past heavy smoking

2.47 [1.96−3.13]

1.66 [1.19−2.31]

0.151

 Current light smoking

2.15 [1.95−2.37]

1.95 [1.73−2.19]

0.144

 Current heavy smoking

4.82 [4.31−5.39]

3.57 [3.11−4.11]

0.018

Occupational status (unemployed/retired subject vs employed subject/house-person/student)

1.11 [0.97−1.28]

1.53 [1.31−1.79]

0.019

Asthma (present vs absent)

2.08 [1.84−2.34]

2.01 [1.77−2.30]

0.635

Allergic rhinitis (present vs absent)

1.76 [1.60−1.93]

1.81 [1.63−2.02]

0.680

  1. * RRs also adjusted for age, season of response, type of contact, cumulative response rate, and centre.
  2. p-value obtained by considering the data from both the studies in the model and by testing the null hypothesis that the regression coefficient of the interaction term between the covariate and the dummy indicator of the study (GEIRD vs ISAYA) was zero.