[quickthrower2]

I’m going to guess (article won’t load for me) it is because the title should be “proportion of elderly deaths is 23% higher for surgery done on surgeons birthday” which might be a different thing if working on your birthday confounds with a certain type of surgery E.g. emergency surgery and being on call vs. elective surgery

[dj_mc_merlin]

That is not correct, the article talks about methodology:

> The patients were all Medicare beneficiaries aged 65 to 99. They had all undergone one of 17 common emergency surgical procedures between 2011 and 2014. Examples of those 17 procedures included cardiovascular surgeries, hip and femur fracture, appendectomy, and small bowel resection. The study focused on emergency surgery, so as to minimize the potential selection bias. For example, surgeons might otherwise choose patients based on their illness severity, or patients might choose their surgeon.

[moosinho]

Good point. That's probably also the case for surgeries on national holidays.

[UncleMeat]

It isn't a good point. This was explicitly controlled for in the study. People are just making wild guesses about methodological limitations that don't exist.

[throwawaylolx]

It is:

>The effect size of surgeons’ birthday observed in our analysis (1.3 percentage point increase or a 23% increase in mortality), though substantial, is comparable to the impact of other events, including holidays (eg, Christmas and New Year) and weekends, which have been argued to affect the quality of patient care.