Arixtra (fondaparinux sodium) was the first selective Factor Xa inhibitor to be marketed. As
with all anticoagulants, an important adverse event associated with Arixtra use is
haemorrhage. Previous studies using clinical trial and observational data show no difference
in the risk of haemorrhage in patients treated with Arixtra compared to (low molecular weight
heparins) LMWHs. This study will assess the risk of haemorrhage in major orthopaedic surgery
patients (hip fracture surgery and/or hip/knee replacement surgery) treated with either
Arixtra or LMWH for thromboprophylaxis and will provide additional observational data from a
European country to strengthen the comprehensive review of haemorrhage and the post-marketing
safety of Arixtra. All patients age 18 years and older with a primary discharge diagnosis for
hip fracture surgery and/or a hospitalization for hip and/or knee replacement surgery from
the PHARMO RLS database in the Netherlands are eligible for participation. For study
inclusion patients must receive either Arixtra or LMWH as initial in-hospital
thromboprophylactic agent and have at least three months in the PHARMO RLS database before
cohort entry date. Patients with a history of hospitalization for haemorrhage, renal failure
or liver failure in the past 3 months will be excluded. Descriptive statistics, including
gender, age, length of treatment, co-morbidities, concomitant medications, and other
covariates will be calculated.
Data for this study were obtained from different registers in the PHARMO medical record
linkage system (PHARMO RLS) in the Netherlands. The PHARMO medical record linkage system is a
population-based patient-centric data tracking system that includes high quality and complete
information of patient demographics, drug dispensing, and hospital morbidity records of
approximately 2.3 million community-dwelling inhabitants of 48 geo-demographic areas in the
Netherlands. The PHARMO registers are linked on a patient level and contain unprecedented
accurate and complete information required for the study.
The out patient database contains drug dispensing data in the U-Expo database are encoded
according to standards based upon the Z-Index drug database (www.z-index.nl). Therefore, it
is possible to identify and classify drug use in time, both on the basis of national and
international classification schemes as well as on the basis of individual active ingredients
and administration forms. Of each dispensed drug, the Anatomical Therapeutic Chemical (ATC)
code, the dispensing date, the prescriber, the prescribed dosage regimen, the dispensed
quantity, the cost and the estimated legend duration of use are available.
The hospital pharmacy database comprises hospital pharmacy data collected in a growing number
of non-academic hospitals in the Netherlands. Currently, data are collected on patient level
for more than one million patients from a representative sample of non-academic hospital
pharmacies scattered over the Netherlands. The hospital pharmacy database includes data on
in-patient medication orders such as type of drug, dose, and time of administration and
duration of use.
The Dutch Medical Register (LMR) is the data source comprising all hospital admissions in the
Netherlands (www.prismant.nl). These records include detailed information concerning the
primary and secondary discharge diagnoses, diagnostic, surgical and treatment procedures,
type and frequency of consultations with medical specialists and dates of hospital admission
and discharge. All diagnoses are coded according to the International Classification of
Diseases, 9th edition (ICD-9-CM). Currently, data until December 2008 are available.