RT Journal A1 Goyal A, Spertus JA, Kosiborod M T1 POtassium levels after acute myocardial infarction—reply JF JAMA JO JAMA YR 2012 FD April 18 VO 307 IS 15 SP 1578 OP 1580 DO 10.1001/jama.2012.487 UL http://dx.doi.org/10.1001/jama.2012.487 AB In Reply: Dr Perren and colleagues raise several concerns about our study. First, history of dialysis was included as a covariate in the mortality models and was not simply a baseline characteristic. Second, although rates of certain therapies and comorbidities differed across subgroups of potassium levels, we did adjust for all of these factors in an attempt to account for these differences. Third, causes of death are not captured in the HealthFacts database. As we stated in our article, the greater number of deaths than ventricular arrhythmia and cardiac arrest events may be due to misclassification bias. However, the rate of ventricular arrhythmia events has decreased substantially during the β-blocker1 and reperfusion era2 and is not as clinically meaningful as mortality.