Disease status and use of ventilatory support by ALS patients. BDNF Study Group

Use of mechanical ventilation (MV), administered either invasively via tracheostomy, or more commonly non-invasively (CPAP, BiPAP), appears to be increasing in ALS. No prospective databases exist that describe the behavior of physicians and patients and the criteria for instituting MV in ALS.

387 placebo patients in a Phase III trial of r-metHuBDNF were followed for 9 months. Although the use of MV was not the primary end-point of the trial, information was gathered regarding it by cataloging respiratory adverse events and tracking health resource utilization.

35 of 387 patients utilized MV during the trial. Twenty-eight (7%) patients received BiPAP. Seven (2%) were tracheotomized without first receiving BiPAP. Forced vital capacity (FVC): BiPAP patients had a mean ( SEM) FVC% of 71.8 +/- 2.8% and ALSFRS of 27.7 +/- 1.0 at baseline; non-BiPAP patients had a mean baseline FVC% of 88.7 +/- 1.0%, and an ALSFRS of 30.3 +/- 0.3. Symptom duration at entry was similar for both groups (2.1 +/- 0.4 years vs. 2.1 +/- 0.1 years). At the time of first use of BiPAP, average FVC% was 47.5 +/- 4.0% and ALSFRS score was 22.4 +/- 1.5. The range of FVC% at start of BiPAP was 15-87. The nine-month survival was 67.9% for BiPAP patients vs. 86% for non-BiPAP patients. The use of BiPAP varied tremendously among the 38 study sites, with some not employing it at all and others using it in as many as 40% of patients.

Of the 9% of placebo patients who received MV, BiPAP patients were more rapidly progressing than non-BIPAP patients, and showed a greater eventual mortality rate. Patients began MV at a wide range of values of FVC%, and centers differed in their prescribing practices. Factors influencing BiPAP use are complex, and not strictly related to FVC%.