Venous thromboembolism in the elderly: introduction and overview.

The indications for anticoagulation therapy, the available agents, and our knowledge about how best to manage such therapy have increased dramatically over just the last few years. Most of the indications for anticoagulation have a much higher prevalence in the elderly than in younger patients. This makes the management of such patients more challenging because the elderly are more prone to thromboembolism, they may be more sensitive to the effects of certain antithrombotic agents, the pharmacokinetics of these agents may be altered by the aging process, the elderly are at a greater risk of major bleeding, and they frequently are taking more medications, a fact that increases the risk of drug interactions. We are very pleased to be able to provide the readers of this journal with a categorized bibliography of some of the best references in this area provided by national authorities in the clinical management of anticoagulation. First, Dr. Fred Anderson, from the University of Massachusetts Medical Center, provides us with selected references that address the epidemiology of venous thrombosis in the elderly. Dr. Anderson is one of the pioneering investigators in this area, and it is his own work that has demonstrated the marked increase in venous thrombosis among elderly hospitalized patients. The second section of bibliographical entries deals with a number of areas related to warfarin use in the elderly. Dr. Ann Wittkowsky, from the University of Washington Medical Center, provides us with an extensive list of selected references that address how the pharmacokinetics and pharmacodynamics of warfarin metabolism in the elderly differs from what is seen in younger patients. Next, Dr. Rebecca Beyth, from Case Western Reserve University, lists key references that examine the increased risk of bleeding related to the use of warfarin in the elderly. Finally, Dr. Philip Hansten, from the University of Washington School of Pharmacy, includes selected citations that cover the critical area of warfarin drug interactions, which is a particular concern in the elderly. The fourth section deals with new information on the use of unfractionated heparin, low molecular weight heparins, and heparinoids. Dr. Spinler and Ms. Evans, from Philadelphia College of Pharmacy and Science at the University of Pennsylvania, in addressing the literature on several new agents, have taken a slightly different approach than that used by the authors in the preceding section on warfarin. First, they provide sources that address the effectiveness of these agents, followed by references on pharmacokinetic differences in the elderly; and they conclude with citations dealing with adverse reactions of these agents in the elderly. Personal communication with these authors indicate that they have concluded that the effectiveness of unfractionated heparin, low molecular weight heparins, and heparinoids in the elderly appear to be comparable with that seen in younger patients for either venous or arterial thromboembolism. They point out, however, that pharmacokinetics differences in the elderly may require a reduction in dosage of unfractionated heparin or low molecular weight heparin. Bleeding risks with these agents appear to be higher in the elderly than in the young, but whether the heparinoids exhibit such pharmacokinetic differences or a higher bleeding risk in the elderly remains to be established. The ~nal section, by Dr. David Green and Dr. Paula Podrazik from Northwestern University, provides selected citations dealing with the rapidly expanding area of antiplatelet therapy in the elderly. Here again, the authors concluded that the organization of information was best managed in a slightly different format. The references they have selected are grouped into ~ve categories: general reviews, drug interactions, pharmacokinetics and pharmacodynamics, adverse reactions, and miscellaneous. As one might expect, within each of the ~ve categories, the selected references are further subdivided according to speci~c antiplatelet agents (i.e., aspirin, dipyridamole, ticlopidine and clopidogrel, glycoprotein IIb/IIIa inhibitors). Again, through personal communication with these authors, they pointed out that the major use of these agents in the elderly is the prevention of myocardial infarction, the treatment of cerebral transient ischemic attacks and ischemic strokes, and in maintaining patency of coronary artery stents. In most cases, lowdose aspirin alone, ticlopidine alone, or the combination has been used. The safety and ef~cacy of a number of potent, new anti-platelet agents in the elderly needs to be examined. The ~nal category of references in this section (“miscellaneous”) provides some interesting reading on nonantithrombotic uses of these agents in