According to Sandeep Gupta "Intent to Treat" analysis usually produces more conservative estimates of efficacy because the ". . . estimate of treatment effect is generally conservative because of dilution due to noncompliance. Also, heterogeneity might be introduced if noncompliants, dropouts and compliant subjects are mixed together in the final analysis."

In a normal pilot sample one would expect about two patients who regress slowly, in the referenced study each group had about two pilot samples wherefore, about four patients in each group, were the pilot samples normal, would be expected to last at least five years. Such may have been the case in the NIV group as, at the close of the study, approximately thirty months, four patients remained alive but only one did in the DPS group and they decided to undergo tracheostomy. A slow regression patient would likely not need to do so for some time, hence, either the DPS group was not normal or the slow regression patients left the study early.