Table 2.

Baseline Frequency and Severity of AECOPDs and Risk of Moderate AECOPDs, Severe AECOPDs, and Death

	Adjusted HR (95% CI): Cohort Study			Adjusted OR (95% CI) for Risk of Death Associated with Earlier AECOPD Frequency and Severity: Case–Control Study
AECOPD Category	Future Moderate AECOPD (Repeat Events)	Future Severe AECOPD (Repeat Events)	Death	0–12 mo Prior	12–24 mo Prior	24–36 mo Prior
No AECOPDs	1 (reference)	1 (reference)	1 (reference)	1 (reference)	1 (reference)	1 (reference)
1 Moderate	1.71 (1.66–1.77)	1.21 (1.14–1.27)	1.01 (0.93–1.11)	1.18 (0.83–1.67)	1.36 (1.02–1.83)	1.38 (1.02–1.87)
2 Moderate	2.35 (2.27–2.42)	1.61 (1.52–1.72)	1.10 (1.03–1.18)	1.80 (1.19–2.70)	1.56 (1.06–2.31)	1.54 (1.03–2.30)
3 Moderate	2.94 (2.83–3.05)	1.89 (1.76–2.03)	1.25 (1.15–1.36)	1.98 (1.13–3.49)	1.50 (0.95–2.37)	1.57 (0.99–2.51)
4 Moderate	3.41 (3.27–3.56)	2.14 (1.95–2.35)	1.32 (1.20–1.46)	1.00 (0.53–1.86)	2.23 (1.38–3.73)	1.45 (0.75–2.81)
5+ Moderate	5.50 (5.32–5.68)	2.92 (2.73–3.13)	1.57 (1.45–1.70)	2.33 (1.45–3.76)	2.50 (1.56–3.98)	2.80 (1.75–4.48)
1+ Severe	3.27 (3.13–3.41)	3.69 (3.44–3.94)	1.79 (1.65–1.94)	14.16 (9.45–21.20)	4.27 (2.78–6.55)	2.57 (1.61–4.13)

Definition of abbreviations: AECOPDs = acute exacerbations of chronic obstructive pulmonary disease; CI = confidence interval; HR = hazard ratio; OR = odds ratio.

All HRs and ORs are adjusted for age, sex, smoking status, body mass index, comorbidities, and FEV₁% predicted.