Average number of COPD-related hospital days per patient (unadjusted)Adjusted COPD-related hospital days*
EnroleesNon-enroleesRatioIncidence rate ratio95% CI
Total sample excluding those who died†
 First year follow-up2.752.491.100.880.71 to 1.08
 Second year follow-up3.163.220.980.78‡0.64 to 0.95
Alive at start of each year†
 First year follow-up3.992.631.521.170.95 to 1.44
 Second year follow-up3.673.191.150.83§0.67 to 1.02
  • *Adjusted for age, sex, ethnic group, rental flat, coronary heart disease, chronic kidney disease, hypertension, dyslipidaemia, obesity, asthma, diabetes mellitus, usage of tiotropium; generalised estimating equation with the log link function, Poisson distribution and exchangeable covariance structure; incidence rate ratio <1 indicates smaller odds of hospitalisation.

  • †Total sample n=184, n1=172 alive at start of year 1, n2=162 alive at start of year 2.

  • ‡P<0.05.

  • §P<0.10.