Skip to content

“No, cardiac arrests are not more common on Monday mornings, study finds”

Paul Alper points us to this news report by Susan Perry. I have no idea how good this study is—I have not looked at it at all, except to pull out those two ugly-but-somewhat-functional graphs above (where “SCA” stands for “sudden cardiac arrest”)—but I wanted to convey my approval for a news story reporting a study with a negative conclusion.

P.S. This would be a good dataset for fitting this model (see also cover of BDA3).


  1. paul alper says:

    Quite apart from the graphs and the conclusions about time of day for sca, Perry points out the distinction between sca and “heart attack”:
    Sudden cardiac arrest is not the same as a heart attack (myocardial infarction). As the American Heart Association (AHA) explains on its website, “A heart attack is when blood flow to the heart is blocked, and sudden cardiac arrest is when the heart malfunctions and suddenly stops beating unexpectedly.”
    “A heart attack is a ‘circulation’ problem and sudden cardiac arrest is an ‘electrical’ problem,” the organization adds.
    A person who has sudden cardiac arrest will die within minutes if not treated with cardiopulmonary resuscitation (CPR) and defibrillation. Each year, the condition kills almost 600,000 Americans, making it the third-leading cause of death behind cancer and heart disease. Four out of five sudden cardiac arrests occur in the home, and more than 90 percent of those individuals die before they reach the hospital.

  2. paul alper says:

    Those graphs are more interesting than Andrew gives them credit for because they illustrate how “relative” is different from “absolute.” On an absolute basis, sca can happen any time of the day, or the day of the week. On the other hand, on a relative basis, sca is about four times as likely to happen at lunch time compared to very early AM. Big Pharma exploits this confusion by invariably quoting the more impressive relative risk reduction rather than paltry absolute risk reduction.

    • Carlos Ungil says:

      What do you mean by absolute and relative?

      • I think he means that no matter what time of the day, the fraction of all people who have a heart attack today at that time is very small… (absolute rate)

        but the relative risk (ie. the ratio of the risk at say 12PM vs the risk at 1AM) is about a factor of 2, so you can say “you are twice as likely to have a heart attack at noon as you are at 1am”

        Saying “our competitor’s drug quadruples your risk of dying from sudden massive internal bleeding” sounds scary, “our competitors drug makes it so that you have a 1 in 10 million chance of dying of sudden massive internal bleeding compared to our drug which gives you 0.25 in 10 million risk” both sound like very small risks.

        • paul alper says:

          Daniel Lakeland has put it correctly. “Absolute” involves a subtraction, while “relative” has the subtraction and then a division. Each is a legitimate piece of information and I suppose it is always wise/honest to quote both.

          • Carlos Ungil says:

            I may be missing your point. Something that can happen at anytime but is more frequent at some times of the day or the year, or something that can happen to anyone but is more likely for some people, are common occurrences in everyone’s experience. I don’t understand what’s interesting (or problematic) with the charts.

            • George Girton says:

              The charts have reminded people of the fact that, even though they show a recognizable relative difference of the event (cardiac arrest) during the day, that cardiac arrest itself is not too common overall. If you were to note that this is not the fault of the charts, you would not be incorrect! In fact it is very easy to find stories in the news which report on studies showing relative differences which do not mention the absolute rate overall. And they do not explain what a hazard ratio is, either. Well, I have never seen that, anyway.

Leave a Reply