Letter to the Editor Haemostasis 2001;31:69–70 Low-Molecular-Weight Heparins, Acenocoumarol and Bone Density L. Wawrzyn ´ ska a J. Przedlacki b B. Hajduk a H. Bielska Falda c W. Tomkowski a A. Torbicki a a Department of Internal Chest Medicine, Institute of Tuberculosis and Lung Diseases, b Department of Internal Medicine and Nephrology, Medical University, c 1st Department of Surgery, Medical University, Warsaw, Poland Liliana Wawrzyn ´ ska Department of Internal Chest Medicine Institute of Tuberculosis and Lung Diseases PL-01-138 Warsaw, Plocka 26 (Poland) Fax +48 22 691 2414, E-Mail I.wawrzynska@igichp.edu.pl ABC Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 2001 S. Karger AG, Basel 0301–0147/01/0311–0069$17.50/0 Accessible online at: www.karger.com/journals/hae Dear Sir, Recently, we published the results of a Polish multicentre trial which showed the efficacy of low-molecular-weight heparin (LMWH) when compared to ace- nocoumarol for secondary prophy- laxis of VTE episodes [1]. How- ever, a growing number of patients without reversible risk factors for VTE are assigned to periods of secondary prophylaxis extending beyond 6 months, because of a per- ceived high risk of late recurrence. Whether LMWH can be consid- ered in this clinical context as an alternative to oral anticoagulants requires an update of our under- standing of the adverse effects of this group of anticoagulants when administered over longer periods of time. We would like to share our initial experience regarding the risk of osteoporosis during secondary prophylaxis with LMWH in pa- tients after VTE. Osteoporosis is a well-recog- nized complication of prolonged treatment with unfractionated hep- arin [2–4]. Generally, the intensity of bone structure disturbance is be- lieved to depend on the total ad- ministered dose of unfractionated heparin. However, only a few pub- lished reports have directly ad- dressed this problem since 1965. Only isolated publications report on the influence of UFH, LMWH and oral anticoagulants on bone structure [5, 6]. Our experience consists of a prospective observation of 54 pa- tients (26 females, 28 males, age 22–75 years, average 56.7 years) assigned to secondary prophylaxis after episodes of VTE. Nadropar- ine (15,000 IU/day s.c.) was used in 15 patients, enoxaparine (1 mg/kg/ day s.c.) in 15 patients and aceno- coumarol (administered to reach a target range of INR 2.0–3.0) in 24 patients. Each patient was evaluated for bone structure abnormalities twice: firstly after 10–14 days of initial treatment for VTE and then after either 3 months of secondary pro- phylaxis in those patients who re- ceived nadroparine or acenocou- marol or after 6–12 months in those receiving enoxaparine. Bone structure was assessed by densi- tometry (according to the DEXA method with LUNAR DPX-L, Lu- nar, Madison, Wisc., USA). Two different bones (femur and lumbar spine 2–4) were studied. The initial bone mineral density (BMD) as measured by densitometry was as- signed a value of 100% and com- pared to the final BMD result, expressed as the percentage differ- ence from the initial value. In addi- tion, the Z score was assessed, de- fined for individual patients as the number of standard deviations from an ideal BMD value for age and sex subgroups.