Extended anticoagulation after joint replacement - Academy News at the 2007 AAOS Annual Meeting

Extended anticoagulation after joint replacement reduces PE

By Jennie McKee

Venous thromboembolism (VTE) is the most common reason for hospital readmission and death after total hip (THA) and total knee arthroplasties (TKA).

According to poster exhibit P016, the use of low-intensity warfarin (target international normalized ratio [INR] of 2.0) on an extended outpatient basis effectively reduces pulmonary embolism (PE) and readmission for VTE with little bleeding risk.

Researchers note that even surveillance venography is a poor predictor of the need for VTE prophylaxis after discharge following total joint arthroplasty. This retrospective study involved 3,293 patients—1,972 of whom had THA and 1,321 of whom had TKA—treated from 1984 to 2003. Screening contrast venography was performed for all patients. Patients whose tests showed deep vein thrombosis (DVT) received warfarin for 6 weeks (for calf DVT), 12 weeks (for thigh DVT), or 24 weeks (for PE). A six-month postoperative audit noted readmission for DVT, PE and bleeding.

The results of the 1,842 positive venograms showed that 17 percent of THA patients (175/1,032) and 42.3 percent of TKA patients (343/810) had DVT. The use of epidural anesthesia reduced DVT prevalence only in THA patients (14.2 percent [THA] vs. 22 percent [TKA]; p = 0.0008). Among THA patients, 32 (1.62 percent) were readmitted for VTE—14 with PE and 18 with DVT. Among TKA patients, eight (0.6 percent) were readmitted for VTE—three with PE and five with DVT (p = 0.009).

From 1984 through 1992, patients whose studies were negative (n = 1,357) received no further anticoagulation after discharge. Among this group, 2.2 percent of THA patients (19/880; p = 0.013) and 1.05 percent of TKA patients (5/477; p = 0.12) were readmitted. Four patients (three THA patients and one TKA patient) suffered fatal PE.

From 1993 through 2003, even patients with negative results (n = 844) were prescribed warfarin for six weeks. During this time period, the readmission rate dropped to 0.28 percent of THA patients (1/360) and 0.21 percent of TKA patients (1/484). One patient had a fatal intracranial bleed while on warfarin.

This comparison indicates that extended warfarin eliminated PE (0/844 vs. 17/2,449; p = 0.01) and reduced readmission (2/844 vs. 38/2,449; p = 0.0015) for VTE. The use of extended outpatient treatment with low-intensity warfarin (INR = 2.0) safely reduces clinical PE and VTE readmissions, even among patients whose initial venographs are negative.

The lead researcher is Vincent D. Pellegrini, Jr., MD of Baltimore; additional researchers include Christopher T. Donaldson, MD, and Daniel C. Farber, MD, both of Baltimore; Eric B. Lehman, MS, of Hershey, Penn.; and C. McCollister Evarts, MD, of Rochester, N.Y. The authors report no conflicts of interest.

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