Quality control of vital capacity as a primary outcome measure during phase III therapeutic clinical trial in amyotrophic lateral sclerosis.

Currently, ALS clinical trials require large sample size and the participation of many clinical evaluators to perform the outcome measure. High variability due to testers, instruments, or patients performance errors may result in systematic bias or random error leading to erroneous or uninterpretable results. Consequently, a quality control system that aims to produce high quality data in terms of reproducibility and accuracy to ensure reliability of the primary outcome measure is essential. In this paper we report our experience in preparing and executing a prospective quality control system that was implemented in conjunction with a large multicenter, multinational randomized placebo-controlled phase III clinical trial in ALS. We have shown that a prospective quality control system is highly effective to ensure inter- and intra-rater reliability of vital capacity as a primary outcome measure during the entire trial.