Friday, October 21, 2016

The moon and hospital admissions

A few days ago we had a full moon. A lengthy discussion about the effect of a full moon on hospital admissions took place on Twitter.

Many papers say admissions increase and odd things happen, and many others have found there is no relationship between the phases of the moon and anything that goes on in hospitals.

Someone sent me a link to a paper that a lot of devotees of astrology like to quote. It's called "The influence of the full moon on the number of admissions related to gastrointestinal bleeding," and it appeared in the International Journal of Nursing Practice in 2004.


The authors looked at the records of 447 consecutive patients admitted with G.I. bleeding to a hospital in Barcelona over two years. There were 26 (an average of 1.04 ± 0.93) admissions during 25 days of the full moon and 421 (0.59 ± 0.78) admissions on the other 713 days where the moon was not full, P = 0.007.

The authors concluded "the number of admissions related to gastrointestinal hemorrhage in our bleeding unit increases during [a] full moon. However, the wide variation in the number of admissions throughout the lunar cycle, as well as the possible influence of other external factors such as atmospheric phenomena, and concomitant with the lunar cycle, could limit analysis and interpretation of the results."

Jean-Luc Margot, a UCLA professor of physics and astronomy, published a detailed critique of the of the above paper in the journal Nursing Research. He pointed out a number of problems. I will share a simple one.

This figure represents the number of admissions for G.I. bleeding plotted against the days of the lunar cycle.
Day 29, when the moon was full (indicated by the circle), had the most admissions—26. In looking at the other days, do you notice anything suspicious?

Here is the figure again with some of the other days highlighted.
Days 9, 12, 13, and 27 all had 23 or more admissions. The difference between the number of admissions on those four days and day 29, the full moon day, is not statistically significant.

Of course another major problem is even if there were significantly more admissions on the day of the full moon, the paper does not prove that the moon was the cause.

Maybe the full moon does affect hospital admissions, but the astrologers won't convince me without a lot better study than the one from Spain.












12 comments:

frankbill said...

Maybe the increase in gastrointestinal bleeding is from werewolves attacks.

Ann Dougherty said...

As a critical care nurse for 40+ years, trust me, full moons cause dread in ICUs. Especially if it is a Friday, payday, and the 13th. All hell breaks loose!

Skeptical Scalpel said...

Fran, you may be right,

Ann, you listed too many confounding variables. :-)

William Reichert said...

When the moon is full,it is easier to see the sign that says
"Hospital ... turn left".

Skeptical Scalpel said...

I never thought of that.

Howard said...

While the belief that days around a full moon increases bleeding risks the number of admissions to hospital is a poor secondary indicator depending as much on the admitting personnel as the symptoms. For many supposed moon related phenomena the days around the dark of the moon supposedly shows an increase, albeit lesser, as well. So those analyses that compare Full Moon numbers VS the rest of the month may mask anything statistically significant.

Anonymous said...

Somewhat related - I do believe barometric pressure influences the risk of kidney stones and gout - and there may be some physical principles to support this, but I have not looked for hard data.

Skeptical Scalpel said...

Howard, what you said.

Anon, I have not seen anything published about that. It would be a tough thing to study. Lots of potential confounders.

Anonymous said...

Anonymous Europe: I just got off my 24 hour shift. I am usually in the outpatient unit during on call. At fullmoon people just go crazy...

Skeptical Scalpel said...

Well, I guess that settles it. :-)

Anonymous said...

Summary of published studies investigating moon phase and behavior: http://faculty.washington.edu/chudler/moon.html

Skeptical Scalpel said...

Anon, thanks for the comprehensive summary of the research on this topic. I hope everyone takes a look at it.

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