Influence of safety warnings on ESA prescribing among dialysis patients using an interrupted time series.

backgroundIn March, 2007, a black box warning was issued by the Food and Drug Administration (FDA) to use the lowest possible erythropoiesis-stimulating agents (ESA) doses for treatment of anemia associated with renal disease. The goal is to determine if a change in ESA use was observed following the warning among US dialysis patients.

methodsESA therapy was examined from September 2004 through August 2009 (thirty months before and after the FDA black box warning) among adult Medicare hemodialysis patients. An interrupted time series model assessed the impact of the warnings.

resultsThe FDA black box warning did not appear to influence ESA prescribing among the overall dialysis population. However, significant declines in ESA therapy after the FDA warnings were observed for selected populations. Patients with a hematocrit≥36% had a declining month-to-month trend before (-164 units/week, p=<0.0001) and after the warnings (-80 units/week, p=.001), and a large drop in ESA level immediately after the black box (-4,744 units/week, p=<.0001). Not-for-profit facilities had a declining month-to-month trend before the warnings (-90 units/week, p=.009) and a large drop in ESA dose immediately afterwards (-2,487 units/week, p=0.015). In contrast, for-profit facilities did not have a significant change in ESA prescribing.

conclusionsESA therapy had been both profitable for providers and controversial regarding benefits for nearly two decades. The extent to which a FDA black box warning highlighting important safety concerns influenced use of ESA therapy among nephrologists and dialysis providers was unknown. Our study found no evidence of changes in ESA prescribing for the overall dialysis population resulting from a FDA black box warning.