Venous thromboembolism risk and prophylaxis in the acute Venous thromboembolism (VTE) is a common complication during and after hospitalization for acute medical illness or surgery. Pulmonary embolism accounts for 5-10% of death in hospitalized patients, making VTE the most common preventable cause of in-hospital death. (2-5). In addition to the acute risk of mortality, VTE is associated with long-term risks of post-thrombotic syndrome (6) and chronic thromboembolic pulmonary hypertension (7). These complications contribute substantially to patient morbidity and raise the costs for public healthcare systems.
Evidence-based consensus guidelines for VTE prophylaxis have been available for more than 15 years (8). Despite the existence of these guidelines,VTE prophylaxis remains underused. (9, 10) Existing studies have assessed compliance with prophylaxis guidelines within defined institutions or countries, (11-13) but to date, the proportion of at-risk patients who should receive prophylaxis globally remains unknown.
Recently a multinational, observational, cross-sectional Epidemiologic International day for the Evaluation of Patients at Risk for Venous Thromboembolism in the Acute Hospital Care setting (ENDORSE) study (1) was conducted between August, 2006 and January, 2007. A chart audit of medical and surgical patients in a large sample of hospitals worldwide. The study assessed the number of patients at risk for VTE in the acute care hospital setting in 358 hospitals across 32 countries and established the proportion of patients who received thrombo prophylaxis according to the recommendations of the American College for Chest Physicians (ACCP) guidelines, evidence-based consensus guidelines (2). Tunisia took part in this study. This paper presents the country-specific data from the 5 Tunisian hospitals participating in the ENDORSE study.

METHODS

Procedures:

Detailed procedures have been described in the primary ENDORSE report (1). Briefly, hospitals with >50 beds, admitting patients with acute medical illnesses and exacerbations of chronic diseases, and scheduled routine major surgical procedures were included in the study. Non-acute and single specialty hospitals were excluded. Hospitals were selected at random from authoritative lists of acute care hospitals in 32 participating countries. In Tunisia, Five hospitals were selected from the Tunisian government health authority’s list. According to the national rules, the approval of the Ethics Committee was obtained for the study in Tunisia. Signed patient consent was not required.
Hospital wards were eligible if they were occupied by acute medical and surgical patients (eg, internal medical, respiratory, or cardiac wards, and general surgical and orthopaedic wards). Psychiatric, paediatric, eye, ear, nose and throat, dermatology,alcohol/drug treatment, rehabilitation, accident and emergency, maternity, chronic, and palliative care wards were excluded.
Patients’ data, including demographics, admission and postadmission diagnoses, risk factors associated with VTE,bleeding risk factors for, the duration of a stay and the type of VTE prophylaxis, were collected from a review of hospital charts on standard case report forms by trained physicians. For inclusion, each patient had to be hospitalized in an eligible ward on the predetermined day of survey. In large hospitals it was possible to survey one ward or floor on any particular day. Each ward was assessed on one pre specified day to allow complete and systematic processing of patient data. For inclusion, each patient had to be an inpatient in an eligible ward on the day it was surveyed. Data abstraction from all eligible charts in selected wards at each hospital was completed within 14 days.

Patients:

Patients aged 40 years or more in eligible medical wards or 18 years or more in eligible surgical wards were screened. Patients were ineligible or excluded from the study if their chart was unavailable, they would normally have been admitted to an ineligible ward, were admitted solely for the treatment of VTE. Enrolled patients were assessed for risk for VTE in accordance with the 2004 ACCP guidelines, which included acutely ill medical patients and those admitted for major trauma or undergoing a major surgical procedure requiring general or epidural anesthesia for at least 45 min (2, 14). Surgical patients were first assessed for age, type of surgery, and duration of anesthesia, and then classified as being at highest, high, moderate, or low risk for VTE as per the ACCP guidelines. The use of recommended types of VTE prophylaxis received by atrisk patients was defined according to specific recommendations from the 2004 ACCP guidelines for the different types of patients at risk. When assessing whether prophylaxis was compliant with the ACCP guideline recommendations, only the type of prophylaxis was considered. Data regarding the dose administered were collected; however, such data are not presented because of different dosing recommendations in different countries and because of variations in the drugs approved in different countries;furthermore, the ACCP does not give global recommendations for dosing schedules. Duration of dose could not be assessed because of the cross-sectional nature of the study.
Patients were considered to have a sufficient risk for bleeding to present a contraindication to anticoagulant prophylaxis if they presented with, or developed during hospitalization, any of the following: intracranial hemorrhage; hepatic impairment; bleeding at hospital admission; active gastro duodenal ulcer; or a known bleeding disorder.

Statistical analysis:

Statistical analyses are discussed in detail in the global primary ENDORSE report (1). Briefly, quantitative data were summarized as median (IQR) and the number of non-missing data were summarized into number and percentage of the population. Rates were calculated from individual patient data. To assess the true occurrence of VTE risk at 25% with a margin of error of 4%. SAS version 9.1 was used for all statistical analysis.

RESULTS

Among the 5 hospitals 4 are academic (Hospitals of La Rabta,Habib Thameur and Abdurrahman Memi à l’Ariana inTunis and hospital Hedi Chaker in Sfax) and one county hospital (Mahares). The number of beds assessed, and reasons for exclusion from assessment, together with the number of assessable medical and surgical patients are shown in figure 1.
A total number of 885 patients were enrolled, 673 (76.0%) on medical and 212(24.O%) on surgical wards. 408 (46.1%) of the enrolled evaluable patients were deemed to be at risk for VTE. 95 (44.8%) surgical patients were at risk, as were 313 (46.5%) medical patients. General characteristics of at- risk patients are shown in table 1. Of the at risk patients in medical wards, 190(61.7%) are men, the median age is 62 years and the median BMI is 24.7kg/m2 and the median length of hospital stay up to survey date was 7.0 days. Of the at risk patients in surgical wards 54(57.4%) are men, the median age is 55 years, the median BMI is 23.9 kg/m2 and the median length of hospital stay up to survey date was 5.0 days.
Risk factors for VTE that were present before admission and the post admission factors are shown in table 2. In medical patients the most common VTE risk factors present prior to hospital admission were chronic pulmonary disease (32.5%), chronic heart failure (11.9%) and obesity. In surgical patients the most common VTE risk factors prior to hospital admission were obesity (8.9%) and chronic heart failure (6.7%). In medical patients the most common VTE risk factors present during hospital admission were cardiovascular disease (40.0%), pulmonary infection (36.1%) and acute non infectious disease.

Figure 1 : Selection of study population and reasons for exclusion 

voir figure-1

In surgical patients the most common risk factors present during hospital admission were gastro-intestinal and hepatobiliary conditions (27.4%), non respiratory infections (20.0%), cardiovascular disease (13.7%) and active malignancy (12.6%).The type of first major operation during the current admission is shown in table 3.

Table 1 : General characteristics of patients


Table 2 : Risk factors of VTE
voir tableau-2

Table 3 : Type of 1st major operation during the current hospital admission



The most common contraindication to pharmacological prophylaxis (Table4) is bleeding at hospital admission (4.5%) in medical patients and (4.2%) in surgical patients. 25 (8.0%) of at risk medical patients and 10 (10.5%) of at risk surgical patients were considered to have a high bleeding risk, sufficient to present a contraindication to pharmacological prophylaxis.

Table 4 : Risk factors for bleeding present at current admission



167 (41, 0%) patients deemed to be at risk for VTE received ACCP-recommended types of prophylaxis, of whom 92 (29,4%) were medical patients and 74 (79%) were surgical patients. The rate of prophylaxis is low even in medical patients with high risk such as congestive heart failure (22%) and malignancy (29,6%) which is noted in other studies (18,19).
Anticoagulants were the sole form of VTE prophylaxis; lowmolecular–weight heparin was the most commonly used (Table 5). The mechanical prophylaxis was never used.

Table 5 : Anticoagulant VTE Prophylaxis ordered during hospital admission



DISCUSSION

This first Tunisian survey which is a part of an international cross-sectional study(1) shows that about half (46%) of all hospitalized patients are at risk for VTE, then worldwide 52% of hospitalized patients were at risk for VTE. 41% in Tunisia then 51% worldwide of the at risk patients received an ACCPrecommended prophylaxis. The use of prophylaxis in at risk surgical patients (78%) is higher than worldwide but the recommended prophylaxis is poor in the at risk medical patients (29%).    The low use of prophylaxis have been related in other studies IMPROVE (13) 60% and CURVE (17) (16%).The difference between surgical and medical patients is seen worldwide this fact could result from several factors. First, the benefits of prophylaxis in the surgical setting have been accepted for many years, while trials in medical patients have been more recent and physician awareness for VTE risk is lower in this population. Second, assessment of VTE risk in surgical patients is easier than in medical patients, the principal criteria is the type of surgery rather than a range of illnesses and risk factors as presented in medical patients. Eight per cent in at risk medical patients and 10, (5%) in at risk surgical patients have a contraindication to pharmacological prophylaxis but this fact is not sufficient to justify the low rate of prophylaxis. In another hand these patients could have received the ACCP recommended mechanical prophylaxis but mechanical methods aren’t used in Tunisia probably because a low physician awareness and the cost.
This study have some limitations, the small country- specific size and participating hospitals might not be representative of all hospitalized patients for example there are no orthopedic patients. Some excluded patients may have been at VTE risk.
The Cross sectional design without follow-up so the assessment is limited to duration of hospital stay and cannot evaluate whether prophylaxis duration complies with ACCP recommendations .The use of the 2004 ACCP Guidelines can be criticized, but they were adopted as the best established and most widely referenced standard, and have been used in other studies of VTE prophylaxis (10 -12). The data show that a large proportion of hospitalized Tunisians patients as in other countries are at risk of VTE, and that recommended VTE prophylaxis is underused. VTE in Tunisia, is probably a public health problem with potential risk of mortality and morbidity (14) like in other countries (20, 21), other studies are needed to confirm it. Hospital strategies to assess patients VTE risk should be implemented, with measures that ensure that at risk patients receive appropriate VTE prophylaxis.

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