dr-exmedic.com

Sometimes, it’s easy to skip reading a study that could be important and just use the abstract to bolster an argument.  This can be dangerous, since there are many factors within a study that could affect the accuracy of the numbers, and none of those problems will show up in the abstract.  Sometimes, problems with a study are a bit more obvious.  Consider for a moment a study which used the infamous OPALS data set to look at whether transport time of cardiac arrest victims made a difference in their survival, and which came to this conclusion:

In a large out-of-hospital cardiac arrest study from demographically diverse EMS systems, longer transport interval was not associated with decreased survival.

Sounds like a good reason to bypass a local hospital that can’t provide treatments such as emergency cardiac catheterization and therapeutic hypothermia, doesn’t it?  Well, as much as a good idea as that is, this particular study’s support of the notion comes from numbers that don’t seem useful to me, available without even so much as reading one word from the actual study:

Median transport interval was 4.0 minutes (25th quartile 3.0 minutes; 75th quartile 6.2 minutes) for survivors and 4.2 minutes (25th quartile 3.0, 75th quartile 6.2) for nonsurvivors.

First of all, there’s a misprint somewhere:  within the article, Table 2 gives these numbers for the nonsurvivors, but gives quartile scores for survivors of 2.6 and 5.8.  Ignoring that, if you tease out what those numbers actually mean, you will realize that 75% of all patients made it to a hospital within 6.2 minutes…and that the investigators couldn’t find a difference in transport time between survivors and non-survivors. 

With transport times that short, you’re not going to find a difference. When you’re talking about bypassing the community hospital 6 minutes away for the tertiary care facility 10 minutes away, the choice is a no-brainer (and in fact my wife brought me such a patient the other day–thanks, dear!).  It’s when you’re talking about 6 minutes to the nearest hospital vs. 30 minutes to that tertiary care facility that the decision is a little more dicey–and this study could easily be taken out of context to suggest that it supports the latter.  Thankfully, even the authors admit that they haven’t shown anything about longer transports in general.