Effect of gastrostomy insertion and age on the survival of patients with motor neuron disease (MND) using home non-invasive ventilation

Background: Non-invasive ventilation (NIV) has become a component of standard MND care. Local experience is that bulbar patients are offered NIV for symptom control, and are referred for early feeding gastrostomy. More elderly MND patients are also being referred. We hypothesised that local MND survival may be lower in bulbar patients receiving NIV, but improved by gastrostomy, independent of age. Methods: MND patients referred for respiratory monitoring or NIV assessment at a regional hospital during 2012 to 2017 were analysed retrospectively. Survival status at 12-months was analysed by Kaplan-Meier according to bulbar (onset or dominant) disease status, gastrostomy insertion and above average age (>70-years) at NIV initiation. Results: 72 patients were referred for NIV; 63 were commenced and compliant for greater than one week. Median survival after NIV initiation was 230 days. Bulbar patients (N=19) did not have reduced survival at 12-months (P=0.12). All bulbar and 20% of non-bulbar onset MND patients using NIV had a gastrostomy. Gastrostomy insertion was associated with improved 12-month survival (P=0.04). Cox regression analysis using covariates of age (>70-years), gastrostomy insertion, bulbar disease and IPAP, suggested that increased age (>70-years) was the only independent predictor of mortality at 12-month (hazard ratio: 2.5, 95% CI 1.2 to 5.3, P=0.02). Discussion: Multidisciplinary care including NIV may be associated with improved survival in bulbar motor neuron disease. It is unclear whether findings in our older MND patients suggest lead time bias (delayed diagnosis or NIV initiation), or altered decision making about NIV withdrawal.