Preventing Venous Thromboembolism Following Hip Replacement Surgery: Analysis of Special Populations in the United States That May Require Alterations to Anticoagulant Regimens

Background:

Patients undergoing hip replacement surgery are at particularly high risk of venous thromboembolism (VTE) and require thromboprophylaxis. Unlike clinical trials, real‐world surgery includes patient populations with comorbidities or on concomitant drugs, who may require alteration of standard anticoagulant regimens. Our objective was to evaluate the proportion of special patient groups present within the real‐world hip surgery population and to assess prophylaxis status and VTE‐related outcomes.

Methods:

Records for patents ≥ 18 years with hip arthroplasty as their primary Current Procedural Terminology (4th edition) code during 2007 were extracted from IMS's PharMetrics© Patient‐Centric database. Prevalence, prophylaxis status, and outcomes were assessed in the following subpopulatons: history of acute coronary syndromes (ACS); concomitant use of a cytochrome P450 3A4 (CYP3A4) inhibitor; renal insufficiency (acute renal failure, chronic kidney disease, and renal failure); hepatic impairment (chronic liver disease, hepatitis, and cirrhosis); chronic warfarin use; concomitant use of antiplatelet drugs (clopi‐dogrel, ticlopidine, and aspirin); atrial fibrillation (AF); and age ≥ 75 years.

Results:

A large proportion of the 11,483 patients included were ≥ 75 years (26%), used a CYP3A4 inhibitor (20%), had chronic warfarin use (9%), or had AF (9%). Smaller proportions had renal insufficiency (5%), used antiplatelet drugs (3%), had a history of ACS (2%), or had hepatic impairment (1%). Only 44% of inpatients received pharmacological prophylaxis. Lower prophylaxis rates were observed in inpatients ≥ 75 years (27%) or with renal insufficiency (32%). The 2 most commonly prescribed anticoagulants were warfarin (27%) and enoxaparin (15%). The likelihood of VTE events was significantly increased in patients with renal insufficiency and chronic warfarin use and with each increasing year of age (Table 1). Odds ratios for major bleeding were significantly increased in patients with hepatic impairment and chronic warfarin use and with each increasing year of age (Table 1).

Conclusions:

This study highlights that special patient populations are prevalent in the real‐world hip surgery population and that this can affect efficacy and safety outcomes. Studies on the effects of different patient characteristics on VTE‐related outcomes are warranted, particularly with new anticoagulants where few real‐world data exist.

Financial disclosure:

sanofi‐avends U.S., Inc., provided funding to HCO Research to perform this study.

Author Disclosure:

S. Deitelzweig, sanofi‐aventis, honoraria, research funding, speakers bureau; Bristol‐Myers Squibb, honoraria, research funding, speakers bureau; Scios, honoraria, research funding, speakers bureau; Pfizer, speakers bureau; J. Lin, sanofi‐aventis U.S., Inc., employment; A. Ryan, sanofi‐aventis U.S., Inc, research funding.