Table 1.
Baseline characteristics of the COPD study population grouped by low (<2/year) versus high (≥2/year) exacerbation rate
| Patients with full follow-up (study population)a
(n = 14,603) |
Subgroups of study population | ||
|---|---|---|---|
| Patient characteristics | Patients with <2 exacerbations/year (n = 13,709) | Patients with ≥2 exacerbations/year (n = 894)b | |
| Sex, male, n (%) | 7,749 (53 · 1) | 7,322 (53 · 4) | 427 (47 · 8)‡ |
| Age at study baseline, years; mean (SD; range) | 66 · 5 (11 · 5; 40–110)‡ | 66 · 5 (11 · 6; 40–110) | 67 · 4 (10 · 3; 40–93)‡ |
| Full dataset available (censored data), n (%) | |||
| Full data available | 13,709 (93 · 9) | 894 (6 · 1) | |
| Deceased | N/A | N/A | N/A |
| Moved | N/A | N/A | N/A |
| Nursing home | N/A | N/A | N/A |
| Unknown | N/A | N/A | N/A |
| Comorbidity data | |||
| Number of comorbid diseasesc, mean (SD; range) | 3 · 0 (2 · 3;0–20)‡ | 3 · 0 (2 · 3;0–16) | 3 · 4 (2 · 5; 0–20)‡ |
| Number of comorbid diseases categoriesc, n (%) | |||
| 0 | 1,777 (12 · 2) | 1,700 (12 · 4) | 77 (8 · 6) |
| 1 or 2 | 5,305 (36 · 6) | 5,021 (36 · 6) | 284 (31 · 8) |
| 3 or 4 | 4,258 (29 · 2) | 3,977 (29 · 0) | 281 (31 · 4) |
| 5 and more | 3,263 (22 · 3)‡ | 3,011 (22 · 0) | 252 (28 · 2)‡ |
| Exacerbations | |||
| Number of exacerbationsd, mean (SD; range) | 0 · 75 (1 · 5;0–15)‡ | 0 · 44 (0 · 8;0–2) | 5 · 6 (2 · 0;3–15)‡ |
SD standard deviation, N/A not applicable
* p < 0.05, † p < 0.01, ‡ p < 0.001
a p-values displayed are calculated for the difference between patients lost to follow-up versus patients with full follow-up. Chi-square tests for categorized variables and independent t-tests for continuous variables. p < 0 · 05 was considered statistically significant
b p-values displayed are calculated for the difference between the subgroups <2 versus ≥2 exacerbations/year. Chi-square tests for categorized variables and independent t-tests for continuous variables. p < 0 · 05 was considered statistically significant
cpresence of any type of comorbid disease was assessed at study baseline, i.e., 1 January 2012
dMean number of exacerbations during the study period, 1 January 2012 – 31 December 2013
Baseline characteristics of the initial population of all COPD patients (n = 16,427) and those who were lost to follow-up (n = 1,824) are reported in Appendix 3