This study is WORTHLESS.
The major issue I have with this study is that
it was designed from the start with conditions that will automatically favor constant-pressure CPAP over Auto-CPAP (APAP) in the outcomes. Hardly a
truly scientific study, IMHO.
Two points that prove the bias of this study against APAP machines:
1) Please note this statement from the article: "
In this study, fixed CPAP was set at the level determined during titration study, while APAP was set so as to deliver pressure levels from 4 to 15 cm H2O." The problem with this is that (as jdireton pointed out), these APAP pressure ranges are nearly "wide-open" - meaning that there is a very wide range of pressures where the machine is allowed to operate (spanning 11 cmH2O altogether). It's quite known that Auto-CPAP is MUCH more effective at reducing AHI when the range of pressures is tightened up closer to something like 2 under and 2-3 over the titrated pressure. (in other words, if the patient's titrated pressure was 10, the best APAP pressure range for most patients would be 8-12 or 8-13).
By operating in such a wide-open pressure range of 4-15, the study participants are bound to have less effective treatment from APAP. This is a biased baseline point that they should have accounted for, but did not.
2) In this study,
those who used APAPs were given VERY OLD AUTO-CPAP MACHINES. They state for the auto-CPAP patients, they were using a
ResMed AutoSet T, which came out in 2001 for goodness sake! The APAP algorithms and technology has improved
dramatically since that machine came out 10 years ago! Please note that this article was written in 2007, and even then, the AutoSet T was older technology.
Again, they seemed to intentionally design the study to come to the conclusion that constant-pressure CPAPs were better, but they can only do that by
stacking the deck against APAPs, both in pressure ranges and by using older technology.
Sad attempt... and I almost wonder what agenda they have in doing such a biased study.
