Table 4 COPD hospitalisations during 25 years of follow-up in relation to number of raised inflammation-sensitive plasma proteins (ISPs) and smoking status
Number of raised ISPs
012⩾3
Never smokersn = 742n = 388n = 149n = 136
    COPD, n (per 1000 person-years)5 (0.3)10 (1.0)1 (0.3)4 (1.2)
    Age-adjusted HR (95% CI)1.03.5 (1.2 to 10.4)1.0 (0.1 to 8.2)4.3 (1.1 to 16.3)
Former smokersn = 704n = 337n = 164n = 129
    COPD, n (per 1000 person-years)12 (0.7)6 (0.7)3 (0.7)6 (2.0)
    Age-adjusted HR (95% CI)1.01.0 (0.39 to 2.8)1.1 (0.30 to 3.8)2.9 (1.1 to 7.8)
Current smokersn = 577n = 677n = 481n = 763
    COPD, n (per 1000 person-years)35 (2.5)45 (2.8)33 (3.0)98 (5.8)
    Age-adjusted HR (95% CI)1.01.1 (0.72 to 1.8)1.2 (0.76 to 2.0)2.5 (1.7 to 3.6)

  • CI, confidence interval; COPD, chronic obstructive pulmonary disease; HR, hazard ratio.