Feature Article
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Abstracts From Recent Medical Literature For the Geriatric Practitioner Abstracts From Recent Medical Literature For the Geriatric Practitioner
Preoperative or Postoperative Start of Prophylaxis for Venous Thromboembolism With Low-Molecular–Weight Heparin in Elective Hip Surgery?
Prophylaxis of venous thromboembolism with low-molecular-weight heparins in patients undergoing major orthopedic surgery is currently initiated in accordance with at least three different regimens: the regimen traditionally used in Europe starts prophylaxis 12 hours before surgery; in North America, it is initiated 12-48 hours after surgery; and the perioperative regimen prophylaxis initiation is either sooner than 12 hours before or 12 hours after surgery. The objective of this study was to assess the relative efficacy and safety of these three low-molecular–weight heparin regimens used to prevent thrombosis after total hip replacement by conducting a systematic review of all published studies that met the set criteria. These criteria were: (1) inclusion in at least one arm of the study of a dose of low-molecular–weight heparin that is approved for both preoperative and postoperative initiation of prophylaxis; (2) use of mandatory bilateral contrast venography, performed between days 6 and 15 postoperatively; (3) continuation of thromboprophylaxis until venography; (4) independent reading of venograms; and (5) assessment of clinically overt major bleeding by predefined criteria. Studies were excluded from the analysis if no separate data could be obtained for patients undergoing elective hip surgery (in case of patient mix), or if they were reported more than once. The incidence of postoperative thrombosis detected by contrast venography was used as the measure of efficacy, and the rate of major bleeding was used as the measure of safety. In the 1926 patients on preoperative regimen, the incidence of postoperative deep vein thrombosis was 19.2% (95% confidence interval [CI], 17-21%). In the cohort of 925 patients who received a perioperative regimen, the rate of deep vein thrombosis was 12.4% (95% CI, 10-14%), while in the group of 694 patients who received a postoperative regimen, it was 14.4% (95% CI, 12-17%). The rate of major bleeding was 1.4% (95% CI, 1-2%) in the preoperative group, 6.3% (95% CI, 5-7%) in the perioperative group, and 2.5% (95% CI, 1-3%) in the postoperative group. No convincing evidence was found that starting prophylaxis preoperatively is associated with a lower incidence of venous thromboembolism than starting it postoperatively. Perioperative regimens may lower the risk of postoperative thrombosis; however, if so, this positive effect is counteracted by increased postoperative major bleeding.
Strebel N, Prins M, Agnelli G, Büller HR. Preoperative or postoperative start of prophylaxis for venous thromboembolism with low-molecular-weight heparin in elective hip surgery. Arch Intern Med 2002;162:1451-1456.
Short-Duration Prophylaxis Against Venous Thromboembolism After Total Hip or Knee Replacement: A Meta-Analysis of Prospective Studies Investigating Symptomatic Outcomes
The prevalence of asymptomatic deep vein thrombosis diagnosed by venography following hip or knee replacement in patients remains high despite short-term prophylaxis (ie, 7-10 days of fixed-dose low-molecular–weight heparin or adjusted-dose warfarin, with a target international normalized ratio of 2.0-3.0). The risk of symptomatic events in these patients however remains unclear. A meta-analysis of studies conducted from January 1993 to March 2001 was performed in order to obtain reliable estimates of the risk of symptomatic venous thromboembolism occurring within three months of hip or knee replacement in patients who received short-term anticoagulant prophylaxis. MEDLINE, EMBASE, and Cochrane databases, supplemented by bibliographies and conference abstracts, were searched to identify prospective studies of this patient population. The studies were classified into clinical outcome studies if the outcome was symptomatic venous thromboembolism, and venographic outcome studies if the outcome was asymptomatic deep vein thrombosis diagnosed after bilateral venography. The results reflected four clinical outcome studies with 6089 patients who had three months of follow-up, and 13 venographic outcome studies with 7080 patients who had venography 7 to 10 days after surgery. In clinical outcome studies, the three-month incidence of nonfatal venous thromboembolism was 3.2% (95% confidence interval [CI], 2.0-4.4%), and the three-month incidence of fatal pulmonary embolism was 0.10% (95% CI, 0.02-0.20%). The postprophylaxis incidence of nonfatal venous thromboembolism was 2.2% (95% CI, 1.4-3.0%), and the incidence of fatal pulmonary embolism was 0.05% (95% CI, 0-0.12%). The postprophylaxis incidence of symptomatic venous thromboembolism was higher after hip replacement than after knee replacement (2.5% vs 1.4%; P =.02). In venographic outcome studies, the prevalence of deep vein thrombosis (total and proximal) was higher after knee than after hip replacement (total: 38.8% vs 16.4%; P <.001; proximal: 7.6% vs 3.8%; P <.001). This study concluded that approximately one in 32 patients who undergo hip or knee replacement and receive short-term anticoagulant prophylaxis will develop symptomatic nonfatal venous thromboembolism, and approximately one in 1000 patients will develop fatal pulmonary embolism within three months of surgery. In addition, while the prevalence of asymptomatic deep vein thrombosis is more than twofold higher after knee replacement than after hip replacement 7-10 days following surgery, in the subsequent three months the prevalence of symptomatic venous thromboembolism is higher after hip replacement than knee replacement.
Douketis JD, Eikelboom JW, Quinlan DJ, et al. Short-duration prophylaxis against venous thromboembolsim after total hip or knee replacement: A meta-analysis of prospective studies investigating symptomatic outcomes. Arch Intern Med 2002;162:1465-1471.
Adherence With Statin Therapy in Elderly Patients With and Without Acute Coronary Syndromes
Landmark clinical trials have demonstrated the survival benefits of statins, which usually start following 1-2 years of treatment. Earlier research of older lipid-lowering agents demonstrated low levels of one-year adherence. The objective of this study was to compare two-year adherence following statin initiation in three cohorts of patients: those with recent acute coronary stroke (ACS), those with chronic coronary artery disease (CAD), and those without coronary disease (primary prevention). The study was conducted on linked population-based administrative data from Ontario, Canada, on patients age 66 years and older who received at least one statin prescription between January 1994 and December 1998 and who did not have a statin prescription in the previous year. These patients were followed up for two years from their first statin prescription: 22,379 with ACS, 36,106 with chronic CAD, and 85,020 in the primary prevention cohort. Adherence to statins, as an outcome measure, was defined as a statin dispensed at least every 120 days after the index prescription for two years. Two-year adherence rates in the ACS, chronic CAD, and primary prevention cohorts were only 40.1%, 36.1%, and 25.4%, respectively. Relative to the ACS cohort, nonadherence was more likely among patients receiving statins in the chronic CAD (relative risk [RR], 1.14; 95% CI, 1.11-1.16) and primary prevention cohorts (RR, 1.92; 95% CI, 1.87-1.96). Researchers concluded that elderly patients with and without recent ACS have low rates of adherence to statins, which implies that many patients initiated on statin therapy may receive no or limited benefit from statins due to premature discontinuation.
Jackevicius CA, Mamdani M, Tu JV. Adherence with statin therapy in elderly patients with and without acute coronary syndromes. JAMA 2002;288:462-467. Annals of Long-Term Care - ISSN: 1524-7929 - Volume 10 - Issue 11 - November 2002 |