A study can define injury using a blood test, but it also needs a rule for cases in which no test was ordered. That rule matters when comparing different hospitals, types of surgery or times of day.
How the study defined myocardial injury
Prin and colleagues analyzed more than 1.7 million noncardiac surgery cases. They used a troponin-I threshold of 0.03 ng/mL from anesthesia start through 72 hours after anesthesia ended and treated cases without perioperative troponin measurements as negative in the analysis. The overall midazolam association was close to null, although the paper reported a stronger association in overnight cases.
What to ask when the study is cited
Check how often the study groups were tested, why tests were ordered and how missing measurements were handled. A recorded result below the threshold and a missing test may enter the model the same way, while the clinical records show different evidence. For an individual case, review actual troponin values and timing, symptoms, other perioperative events, and the rationale for testing.
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