White RH, Gettner S, Newman JM, Trauner Kb, Romano PS.
Predictors of rehospitalization for symptomatic venous thromboembolism after
total hip arthroplasty.
N Engl J Med 2000 Dec 14;343(24):1758-64

Department of Medicine, University of California, Davis, Sacramento, USA.
rhwhite@ucdavis.edu

BACKGROUND: Recent studies have shown that symptomatic venous thromboembolism
after total hip arthroplasty most commonly develops after the patient is
discharged from the hospital. Risk factors associated with these symptomatic
thromboembolic events are not well defined. METHODS: Using administrative data
from the California Medicare records for 1993 through 1996, we identified 297
patients 65 years of age or older who were rehospitalized for thromboembolism
within three months after total hip arthroplasty. We compared demographic,
surgical, and medical variables potentially associated with the development of
thromboembolism in these patients and 592 unmatched controls. RESULTS: A total of
89.6 percent of patients with thromboembolism and 93.8 percent of control
patients were treated with pneumatic compression, warfarin, enoxaparin, or
unfractionated heparin, alone or in combination. In addition, 22.2 percent and
29.7 percent, respectively, received warfarin after discharge. A body-mass index
(the weight in kilograms divided by the square of the height in meters) of 25 or
greater was associated with rehospitalization for thromboembolism, with an odds
ratio of 2.5 (95 percent confidence interval, 1.8 to 3.4). In a multivariate
model, the only prophylactic regimens associated with a reduced risk of
thromboembolism were pneumatic compression in patients with body-mass indexes of
less than 25 (odds ratio, 0.3; 95 percent confidence interval, 0.2 to 0.6) and
warfarin treatment after discharge (odds ratio, 0.6; 95 percent confidence
interval, 0.4 to 1.0). CONCLUSIONS: In patients who underwent total hip
arthroplasty, a body-mass index of 25 or greater was associated with subsequent
hospitalization for thromboembolism. Pneumatic compression in patients with a
body-mass index of less than 25 and prophylaxis with warfarin after discharge
were independently protective against thromboembolism.