How effective is using oprelvekin for low platelets?

Better than placebo. The study for which oprevelkin was approved by the fda looked at how good the drug was at preventing need for platelet transfusions following chemotherapy for solid cancers. It was effective 28-65% of the time vs placebo (7-41%). Because of its mediocre effectivity and a high list of side effects (swelling, irregular heart beat), it is not widely used compared to just giving platelet transfusions.