Aims: The long-term benefit from noninvasive ventilation (NIV) in chronic hypercapnic chronic obstructive pulmonary disease (COPD) remains uncertain.
Methods: Within a prospective observational design, we compared the long-term survival of 140 patients with severe persistent hypercapnic COPD (FEV(1) 28.7 +/- 8.7% predicted; PaCO(2) 60.1 +/- 9.2 mmHg) with (n = 99) or without (n = 41) NIV. End-point was all-cause mortality, determined up to 4 years by Kaplan-Meier analysis. Additionally, Cox's proportional hazards regression and stratification by risk factors was performed. Patients were characterised by anthropometric and functional parameters, comorbidities and medical therapy.
Results: Adherence in patients with NIV was high (88.9%), daily ventilator use being 6.4 +/- 2.6 h/day and inspiratory pressures 21.0 +/- 4.0 cmH(2)O. One- and 2-year survival rates were 87.7% and 71.8%, respectively, in patients with NIV vs. 56.7% and 42.0% in patients without NIV. Survival rates were significantly higher in patients with NIV compared to those without this therapy (p = 0.001; hazard ratio 0.380; 95% confidence interval 0.138-0.606). The difference between groups was still significant after adjustment for differences in baseline characteristics. Moreover, stratification by risk factors revealed beneficial effects, particularly in patients with high base excess (BE; > 8.9 mmol/l), low pH (< 7.41), FEV(1) (< 27.5%) haemoglobin (< 13.8 g/dl) or large hyperinflation (residual volume-to-total lung capacity > 189% predicted) upon inclusion (p < 0.05 each).
Conclusion: In patients with severe chronic hypercapnic COPD receiving NIV at high inspiratory pressure levels and showing high adherence to this therapy, long-term survival was significantly higher than in non-ventilated patients. Patients displaying more severe disease according to known risk factors seemed to benefit most from long-term NIV.