Is it the use of Non Invasive Ventilation for less than four hours in the day sufficient to prolong survival in patients with Amyotrophic Lateral Sclerosis?

Background: Non Invasive Ventilation (NIV) improves survival in patients with Amyotrophic Lateral Sclerosis (ALS). Some studies show that four-hour use of NIV, at home, is not enough to define compliance to treatment. Study objective: to evaluate improve of survival in patients that use NIV for more than four hours a day and the effect of NIV on survival of the patients doing the treatment for less than four hours. Patients. Starting criteria of NIV were: Vital Capacity (VC)= 55±5, PCO2 > 45 mmHg, dyspnea, orthopnea and sleep disturbance. We studied 187 patients and separated them in two groups: tolerating (69 patients tolerating NIV for more than four hours) and not tolerating (118 patients tolerating NIV for less than four hours). The groups were similar to: age of onset (57,62 tolerating vs 62,43 not tolerating), ratio female/male, VC at timing NIV (52,05±13,90 %of predicted value vs 55,75±20,24 % of predict value) and body site of onset (bulbar or spinal);tolerating group: 20 bulbar-onset and 49 spinal-onset;not tolerating group: 44 bulbar-onset and 74 spinal-onset. Results. After the start of treatment with NIV, the survival of tolerating group was of 19 months vs 4 months of the not tolerating group (p= 0,0001). Duration after NIV trial: 69 ALS tolerant patients vs 118 ALS not tolerant patients enlarge We compared the survival of the patients bulbar at onset divided in two group: 20 patients tolerating NIV; 44 patients not tolerating NIV. After the treatment, the survival of tolerating patients was of 13 months vs 4 months of not tolerating group (p=0,0001). Duration after NIV trial in bulbar onset ALS enlarge We divided the not tolerating group in 4 sub-groups depending on the time of use NIV: group 1: 21 patients refusing treatment; group 2: 16 patients using NIV for 1 hour at day; group 3: 28 patients using NIV for 2 hour; group 4: 53 patients using NIV for less than 4 hour. The median survival of group 1 and 2 after the start of treatment was about of 2,5 months vs 5 months of the group 3 and 4 (p< 0,01). Conclusion:Cox regression analysis, made on all 187 patients and including as variables sex, age, site of onset and tolerability to treatment, shows tolerability as the variable more significative to survival. The same analysis made only for 69 patients tolerating treatment (excluding the variable tolerability) confirms the site of onset as the most important negative prognostic factor for survival. So, only the use of NIV for more than four hours a day improves survival.