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patient dialysis would lead to any meaningful misclassification of a dialysis unit's anemia management practice.We disagree with Zhang et al that our findings are inconsistent with a report that the dialysis chain using the smallest doses of ESAs also had the lowest mortality rates. 1 Our model suggests that centers using ESAs the most aggressively across all hematocrit categories would have increased mortality rates relative to the most conservative centers.Therefore, our results are quite compatible with the cited report.We agree with Dr Auerbach that IV iron is a useful aspect of anemia management.However, we note that a study of 10 169 hemodialysis patients found an 11% increased risk of all-cause mortality and a 12% increased risk of hospitalization in patients prescribed more than 10 vials of iron over a 6-month period compared with patients prescribed no iron. 2That study cites 5 abstracts reporting associations between iron exposure and adverse events, including all-cause mortality and infection-related outcomes.It is likely true that most of the risk of anaphylaxis comes with use of high-molecular-weight iron dextran, but many other important aspects of IV iron use are not well understood.There is a lack of evidence on the comparative effectiveness and safety of different iron dosing strategies (including bolus vs maintenance dosing) and of the different iron complexes, which have different pharmacokinetic properties.Changes in reimbursement coupled with evidence suggesting that frequent use of iron may increase hemoglobin in patients who do not respond well to ESAs 3 are likely to lead to increasing use of IV iron for anemia management in hemodialysis patients.This makes it increasingly important to continue studying IV iron to identify agents and dosing protocols that maximize its considerable benefits while minimizing possible harms and unnecessary use.