TABLE 2

Incidence and hazard ratios of chronic obstructive pulmonary disease (COPD) hospitalisation per group of lung function classification method for 689 participants at 55 years of age

NormalFR+LLNFR+LLN+p-value
Subjects n5455688
COPD events n (n per 1000person-years)42 (3.3)14 (12.7)32 (22.1)
COPD events unadjusted hazard ratio (95% CI)1.004.22 (2.30–7.74)7.87 (4.94–12.54)<0.001
COPD events adjusted hazard ratio# (95% CI)1.004.15 (2.24–7.69)7.88 (4.82–12.87)<0.001
COPD events with competing risks regression#,¶ (95% CI)1.003.31 (1.80–6.09)5.53 (3.34–9.15)<0.001
COPD events adjusted hazard ratio# excluding 30 restrictive+ subjects from the normal group (95% CI)1.004.50 (2.40–8.45)8.80 (5.31–14.58)<0.001
Deaths n (n per 1000person-years)542 (42.17)56 (48.53)88 (54.22)
Deaths unadjusted hazard ratio (95% CI)1.001.40 (1.04–1.84)1.63 (1.30–2.05)<0.001
Deaths adjusted hazard ratio#,§ (95% CI)1.001.30 (0.98–1.72)1.58 (1.25–2.00)<0.001
Deaths adjusted hazard ratio#,§ excluding 30 restrictive+ subjects from the normal group (95% CI)1.001.34 (1.01–1.77)1.65 (1.30–2.08)<0.001
  • FR: fixed ratio; LLN: lower limit of normal. #: adjusted for smoking status (three groups: never, ex- and current smokers), diabetes, body mass index, height and physical activity (three groups: high, moderate and low physical activity); : 88 incident COPD cases as failure events and 598 deaths without COPD as competing risks; +: forced expiratory volume in 1 s/vital capacity (VC) ≥70%, VC ≤80% predicted; §: additionally adjusted for systolic blood pressure and cholesterol.