Long Term Outcomes Of Home Non-Invasive Ventilation (Niv) In Patients With Chronic Hypercapnic Respiratory Failure (Chrf) Due To Kyphoscoliosis

Background: The use of NIV in patients with CHRF due to kyphoscoliosis has been shown to improve respiratory function, symptoms and quality of life. The long term effect on mortality is not as clear. We describe our experience with the use of home NIV in these patients and identify factors associated with mortality. Methods: Patients with kyphoscoliosis on home NIV between Jan 2000-Dec 2016 were followed-up from time of initiation to 1st Jan 2018. The primary outcome was all-cause mortality assessed by Kaplan Meier analysis. Cox regression was performed to identify factors associated with mortality. Results: A total of 35 patients were included. The mean age at initiation was 54 ± 13 years, BMI 20 ± 5 kg/m2. The mean arterial blood gas pH at initiation was 7.33 ± 0.06, pCO2 64.1 ± 13.2 mmHg, pO2 72.5 ± 26.1 mmHg. The mean IPAP used was 14.8 ± 3.5 cmH20, EPAP 6.1 ± 1.99 cmH20. The median hours used a day was 6.9 ± 2.8 hours, the median percentage of days used greater than 4 hours was 98% (0-100%). 6 patients declined NIV or did not return for follow up. 11 patients died. The mean length of survival was 12y0.5m (95% CI 9y4m – 14y8m). 1 year mortality was 2.9%, 3 year mortality was 11.4% and 5 year mortality was 20%. Lower BMI (HR 0.73 95% CI 0.59-0.91 p=0.005) and fewer days used more than 4 hours (HR 0.97 95% CI 0.95-0.99 p=0.01) were associated with increased mortality. Age at initiation, low FVC, raised pulmonary arterial systolic pressure were not associated with increased mortality. Conclusion: The use of home NIV has good long term survival for patient with kyphoscoliosis and CHRF. Lower BMI, fewer days of NIV usage predicted reduced survival.