Is Every Side Effect Always Rare? What About Thrombocytopenia Induced by Some Forms of Heparin?

This is nothing that anyone doesn't already know, but every side effect is always described as being rare (http://scholar.google.com/scholar?q=%22is+a+rare%22+%22side+effect%22+OR+complication&hl=en&lr=). Is each of those 77,000+ side effects or complications always rare? This is just in relation to the last posting and the things I saw in it. I'm sorry to have to put this up on the blog, and it's deeply disturbing to me. But I'm going to put it up. This article is called "Finding Haystacks Full of Needles: From Opus to Osler" [Levine, 2005: (http://www.chestjournal.org/cgi/content/full/127/5/1488)(http://www.ncbi.nlm.nih.gov/pubmed/15888818)]. I'm not trying to make any kind of statement by posting this, and I know there's a daily need to use various forms of heparin. That's especially true in view of the absence of any substitute for it or source of more-reliably-nonimmunogenic heparan-based or heparin-like polymers. But the author discusses research estimating or finding evidence to indicate that there are 600,000 cases of thrombocytopenia associated with some forms of heparin (I'll call it "heparin-associated thrombocytopenia") each year. The condition is a form of autoimmunity and is driven by antibodies to different platelet proteins, etc. The research also estimates that 90,000 of those people die each year from it and that 300,000 of them experience thrombotic complications. The condition can go on for months and is very difficult to treat.

The author also notes that the condition is described as being "rare" in almost every instance in which it's discussed. It's fine to state that something is rare, if it is, in fact, rare or if one legitimately thinks it's rare (because of clinical experience, etc.). But one point of that article is that there's frequently a delay to the appearance of the devastating phase of the thrombogenicity, so that people may leave the hospital and may have been forced to discontinue the form of heparin (or may have not had any ill effects at all) and may then develop thromboses a month later. They may then go into the emergency room and be treated with heparin and deteriorate in a dramatic way, as one would expect. So some or many of the cases are probably never recognized. In any case, it's just one of those things. One could say that the researchers made inaccurate estimates of the deaths or complication rates, but I'll bet there's more research that's similar. I don't much feel like seeking it out, the way I wound up doing in the last posting.