Title:
Differences in the reporting rates of serious allergic adverse events from intravenous iron by country and population.

Abstract:
Previous studies have compared rates of adverse events between intravenous (IV) iron preparations; however, there has been no comparison of adverse event rates by country and population.
To compare rates of adverse events to IV iron products by country and population.
All adverse events reported from 18 countries from January 1, 2003 to June 30, 2009 were obtained for iron dextran (ID), iron sucrose (IS), IS similars (ISS), and sodium ferric gluconate (FG). Rates of all adverse events and serious adverse events (anaphylaxis plus other serious allergic reactions) were calculated as number of events per gram of iron sold (gFe) per million inhabitants (mil) × 10-3. Odds ratios (ORs) were calculated for the risks of adverse events between products.
Iron use ranged from 1 gFe/mil (Poland) to 48,674 gFe/mil (Italy). Rates of all adverse events (reports/gFe/mil × 10-3) varied: for IS, it ranged from 0 (Poland, Austria, Czech Republic) to 1,222 (Ireland); for FG, from 3.3 (Czech Republic) to 183.6 (United States); for ID, from 0.9 (Turkey) to 46,875 (Switzerland). There were no reports of adverse events in ISS. In a subset of countries that used 2 or more iron products and had more than 1 serious adverse event, rates (reports/gFe/mil × 10-3) of all adverse events and serious adverse events were lowest for IS (39.8 and 1.7), intermediate for FG (54.8 and 4.5), and greatest for ID (337.7 and 20.5). IS had lower risks for all adverse events (OR, 0.63; P<.0001) and serious adverse events (OR, 0.31; P=.001) versus FG, and for all adverse events (OR, 0.13; P<.0001) and serious adverse events (OR, 0.07; P<.0001) versus ID. FG had lower risks for all adverse events (OR, 0.20; P<.0001) and serious adverse events (OR, 0.24; P<.0001) versus ID.
Considerable international variation existed in the extent and choice of iron product and adverse event reporting, suggesting under-reporting in some instances. Clinicians should appreciate the differential risks between available products, and should critically review local reporting practices.