Introduction Intention-to-treat analysis from the HOT-HMV UK trial showed an improvement in admission-free survival with the addition of home mechanical ventilation (HMV) to home oxygen therapy (HOT) in patients with persistent hypercapnia following an acute exacerbation of COPD [JAMA;317:2177]. Delivery of HMV is essential and a per-protocol analysis was conducted to assess if patients who were adherent had better outcome.

Method Patients were randomised to HOT or HOT-HMV if they had persistent hypercapnia (PaCO₂ >7 kPa) 2 weeks following resolution of respiratory acidosis (pH >7.30) secondary to an acute exacerbation of COPD. NIV was titrated to nocturnal hypoventilation and patients were followed up for 1 year. Patients allocated to the HOT arm that breached safety criteria had HMV added to HOT. Patients were included in the analysis in the HOT-HMV group if they had mean adherence of >4 hours/night. Patients allocated to HOT were included up until trial withdrawal or treatment switching.

Results 57 patients were randomised to HOT-HMV of whom 15 were non-adherent and 11 had missing usage data and were treated as non-adherent. 59 patients were allocated to HOT of whom 5 patients were excluded due to treatment switching. Median time to readmission or death was 1.1 months in the HOT group and 3.7 months in the HOT-HMV group (adjusted hazard ratio (HR) 0.41, 95% CI 0.23, 0.74, p=<0.01). All-cause mortality was reduced in the HOT-HMV group (figure 1; adjusted HR 0.36, 95% CI 0.13, 0.97, p=0.04). There was a significant treatment effect on PaCO₂ at 6 weeks (ΔpCO₂−0.9 kPa, p<0.01) which was observed at 12 months (pCO₂−0.7 kPa, p=0.04) with no significant effect on health related quality of life at 6 weeks (SRI p=0.28, SGRQ p=0.98) or 12 months (SRI p=0.71, SGRQ p=0.31).

Conclusion Patients with persistent hypercapnia following an acute exacerbation of COPD who were adherent to HOT-HMV had a reduced risk of readmission or death and in addition, unlike the intention to treat analysis, had an improvement in gas exchange and a reduction in all-cause mortality at 12 months. Addition of HMV to HOT should be considered for patients with persistent hypercapnia following a life-threatening exacerbation of COPD.

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Abstract S37 Figure 1

Kaplan-Meier plot showing survival from randomisation to end of trial follow up by treatment arm. Adjusted for number of COPD admissions in previous year, prior use of long term oxygen therapy (LTOT), age and BMI.