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To the Editor The large propensity score–matched study by Dr London and
colleagues1 concluded that perioperative use of
β-blockers was associated with lower 30-day mortality in patients undergoing noncardiac
surgery. Two major flaws limit the study’s application as well as the validity of its
The first problem is their choice of conditions included in the propensity score matching of
patients who were either exposed or not exposed to β-blockers. These conditions included angina
within 30 days preoperatively, myocardial infarction 6 months preoperatively, previous coronary
intervention procedure, and congestive heart failure 30 days preoperatively (eTable 5 of the
article). Because use of β-blockers is strictly indicated in patients who have any of these
conditions, the patients who were exposed to β-blockers must be different from those who were
not given β-blockers; unexposed patients might have had a contraindication to β-blockers,
have been too frail to tolerate them, or were treated at a lower level of care.
Mansi I, Mortensen EM. Mortality After Perioperative β-Blocker Use in Noncardiac
Surgery. JAMA. 2013;310(6):645-646. doi:10.1001/jama.2013.8519