Differences in spontaneously reported hypersensitivity and serious adverse events for intravenous iron preparations: comparison of Europe and North America.

Spontaneously-reported rates of adverse events (AEs) of intravenous (i.v.) iron products have not been compared since 2007. AEs in Europe (Eur) and North America (NA) have never been compared. New products have been marketed and many changes in prescribing habits have occurred since then, and the effect on AEs reporting is unclear. It was hypothesized that changing practices for i.v. iron products has caused changes in the rates of serious AEs and large differences exist between Eur and NA. Rates of AEs for three i.v. iron preparations (iron sucrose [IS], ferric gluconate [FG] and high and low MW iron dextran [HMWID, LMWID]) were compared by product and continent from January 1, 2003 to June 30, 2009 for selected countries in Eur and NA, using the Uppsala Monitoring Center's database. Rates of total, anaphylaxis and other serious allergic AEs were calculated as number of AEs divided by i.v. iron sales standardized to 100 mg dose equivalents (DEq) of iron. Quarterly sales (millions of 100 mg DEq of iron) increased from the first quarter 2003 to the end of the second quarter of 2009 by 1% for FG, 16% for IS and 2% for ID. Total AEs for NA plus Eur were similar for FG and IS, but total AEs were 6- to 7-fold higher for ID. Rates of anaphylaxis were 6- to 11-fold higher in Eur plus NA combined for ID than for IS or FG. In NA, there were substantially higher reports for total, anaphylaxis and other serious allergic AEs with FG compared to IS, whereas the reverse was the case in Eur. Odds ratios (OR) showed higher risks of anaphylaxis with FG in NA vs. Eur (OR = 4.40, P < 0.0001) and lower risks with IS (OR = 0.24, P < 0.0001). Odds of anaphylaxis with LMWID in Eur vs. FG and IS were 42.08 and 16.92 (both P < 0.0001), respectively. In NA, odds of anaphylaxis with ID vs. FG and IS were 2.36 and 17.73 (both P < 0.0001), respectively. Differences between NA and Eur may be related to varied treatment practices. ID had the highest rates of all types of AEs, and IS and FG had a continued trend for lowest rates of AEs.