TABLE 4

Multivariate Cox regression analysis of factors associated with survival after categorisation into four new groups

VariableHazard ratio for death (95% CI)p-value
Groups
 No chronic Pseudomonas aeruginosa infection with <2 exacerbations per year1.00 (ref.)NA
 No chronic Pseudomonas aeruginosa infection with ≥2 exacerbations per year1.74 (1.28–2.38)<0.001
Chronic Pseudomonas aeruginosa infection with <2 exacerbations per year0.90 (0.39–2.12)0.81
Chronic Pseudomonas aeruginosa infection with ≥2 exacerbations per year2.03 (1.36–3.03)0.001
Age years1.05 (1.04–1.07)<0.001
Male sex versus female1.29 (1.00–1.68)0.055
Radiology score#1.03 (0.99–1.06)0.11
BMI <18.5 kg·m−21.68 (1.13–2.50)0.011
Smoking status1.11 (0.84–1.47)0.45
MRC dyspnoea score1.24 (1.16–1.45)<0.001
FEV1 % predicted
 <301.00 (ref.)NA
 30–490.66 (0.44–1.00)0.048
 50–790.41 (0.27–0.62)<0.001
 ≥800.43 (0.27–0.68)<0.001
Chronic Haemophilus influenzae infection0.57 (0.39–0.84)0.005
Chronic Staphylococcus aureus infection1.73 (1.10–2.60)0.01
Chronic Moraxella catarrhalis infection0.78 (0.43–1.44)0.43
Chronic Enterobacteriaceae infection0.78 (0.49–1.24)0.29
COPD1.33 (0.98–1.81)0.07
Diabetes1.28 (0.93–1.75)0.13
Chronic renal failure1.58 (1.13–2.23)0.008
Ischemic heart disease1.46 (1.11–1.92)0.007
Oral long-term antibiotic suppressive therapy1.14 (0.86–1.49)0.36
Nebulised long-term antibiotic suppressive therapy0.79 (0.51–1.25)0.32

BMI: body mass index; MRC: Medical Research Council; FEV1: forced expiratory volume in 1 s; COPD: chronic obstructive pulmonary disease; NA: not applicable. #: Reiff score.