Summary
Background
Venous thromboembolism is a common and preventable cause of morbidity and mortality in hospitalized patients. There is a lack of data on the distribution of risk factors and prophylaxis practices in sub-Saharan Africa.
Aim
To assess the prevalence of venous thromboembolism risk in hospitalized patients and to determine the proportion of at-risk patients who receive prophylaxis.
Methods
The study was a cross-sectional hospital-based survey. On the basis of the global ENDORSE methodology, patients aged ≥ 40 years admitted to a medical ward or those aged ≥ 18 years admitted to a surgical ward were assessed for risk of venous thromboembolism by hospital chart review. Distribution of risk factors and coverage of prophylaxis in at-risk patients were determined using the 2004 American College of Chest Physicians evidence-based consensus guidelines.
Results
From October to November 2008, 520 patients (278 medical; 242 surgical) were enrolled in 12 hospitals across Senegal. Two hundred and ninety-eight (57%) were at risk of venous thromboembolism; 152 (57.4%) medical patients and 146 (60.3%) surgical patients. Among those at risk, 48 (31.6%) medical patients and 52 (35.6%) surgical patients received a prescription for prophylaxis. Among patients without contraindication to anticoagulants, 33.8% (46/136) on medical wards and 37.5% (48/128) on surgical wards received prophylaxis.
Conclusion
The risk of venous thromboembolism was frequent in hospitalized patients in Senegal but only a few received the recommended prophylaxis. There is a need to implement a programme to improve venous thromboembolism awareness and prophylaxis.
Résumé
Contexte
La maladie thromboembolique veineuse est une cause fréquente mais évitable de décès et de morbidité hospitalière. En Afrique sub-saharienne, les données sur les facteurs de risque et la prophylaxie sont rares.
Objectif
Évaluer le risque de maladie thromboembolique veineuse chez les patients hospitalisés au Sénégal et déterminer la proportion recevant une prophylaxie.
Méthodologie
Enquête transversale hospitalière. Compte tenu de la méthodologie de l’enquête Endorse, les patients âgés de 40 ans ou plus admis en milieu médical et ceux de 18 ans ou plus en milieu chirurgical ont été étudiés à partir de leur dossier hospitalier. L’évaluation du risque thromboembolique veineux et la détermination de la prescription de prophylaxie ont été faites selon les critères ACCP-2004.
Résultats
D’octobre à novembre 2008, 520 patients (278 en médecine et 242 en chirurgie) ont été inclus dans 12 hôpitaux au Sénégal. Deux cent quatre-vingt-dix-huit, 298 (57 %) présentaient un risque de maladie thromboembolique veineuse dont 152 (57,4 %) en médecine et 146 (60,3 %) en chirurgie. Parmi les patients à risque, 48 (31,6 %) en médecine et 52 (3,6 %) en chirurgie ont reçu une prescription de prophylaxie. Chez les patients à risque ne présentant pas de contre-indication aux anticoagulants, la proportion de prophylaxie était de 33,8 % (46/136) en médecine et 37,5 % (48/128) en chirurgie.
Conclusion
Le risque de maladie thromboembolique veineuse est très fréquent dans les hôpitaux sénégalais. Peu de patients reçoivent la prophylaxie adaptée. Il est nécessaire de mettre en place des programmes pour améliorer la connaissance de la maladie et de sa prophylaxie.
Background
VTE is a common complication that affects patients hospitalized for a variety of medical and surgical conditions. It contributes to longer duration of hospitalization stay, morbidity and mortality, with PE accounting for 5–10% of deaths in hospitalized patients . VTE is often asymptomatic, misdiagnosed and unrecognized at death, as there is a lack of routine postmortem examinations. These factors are thought to result in a marked underestimation of VTE incidence .
VTE in hospitalized patients is often thought of as a consequence of surgery, as major surgery is a risk factor, but medical patients also are at risk. Non-surgical patients account for 70–80% of fatal PE cases and 50–70% of symptomatic thromboembolic events . In an 8-month prospective screening study, DVT was detected by ultrasound in 33% of adults admitted to a medical intensive care unit . The high incidence of DVT in medical patients and the high percentage of patients with VTE who are asymptomatic underscore the importance of identifying and assessing the risk of VTE in hospital patients, so that prophylactic strategies can be implemented . Up to 10% of hospital deaths are caused by PE, suggesting that there is room for improvement in identifying patients at risk of VTE and providing VTE prophylaxis .
Risk factors for VTE are well established. Overall, VTE risk should be perceived as the combined result of constitutional risk factors and the added risk attributable to the patient’s current medical situation and/or surgical procedure . The most common personal risk factors include age > 75 years, cancer (history or current), history of VTE, obesity, varicose veins, hormone therapy (antiandrogen or oestrogen), chronic heart failure and chronic respiratory failure . Medical conditions that increase a patient’s risk of VTE include congestive heart failure, severe respiratory disease, acute medical illness leading to immobility and bed confinement, additional risk factors such as active cancer or previous VTE, and admission to critical care units. . Surgical patients undergoing knee or hip surgery are at highest risk of VTE. Other surgeries, such as trauma or major injury, may also expose patients to a moderate-to-high risk of VTE .
A recent survey (ENDORSE) has provided data on the prevalence of VTE risk and prophylaxis in 32 countries: almost 53% of hospitalized patients were found to be at risk of VTE according to the 2004 ACCP guidelines . There was huge variation in the prevalence of VTE risk between countries (35.6–72.6%) and between types of wards (64% in surgical wards; 41% in medical wards) . The overall proportions of patients at risk of VTE who received adequate prophylaxis were low (58.5% in surgical patients; 39.5% in medical patients). Of note, no sub-Saharan African country was included in this global ENDORSE study.
A possible effect of race and ethnicity on the incidence of VTE has been reported . Some authors have suggested that a higher prevalence of VTE in Caucasians is due to the fact that factor V Leiden is more prevalent in Caucasian than in African-American or Asian populations . However, a recent review of the subject by White and Keenan concluded that African-American patients have a significantly higher incidence of first-time VTE exposure and are more likely to manifest a PE compared with other racial groups, although the incidence of recurrent VTE is similar across racial groups .
There is a relative paucity of studies on the prevalence of VTE and its associated risk factors in sub-Saharan African populations. A retrospective analysis of nearly 1000 postmortem reports in Nigeria found a prevalence of PE of 2.9% . The most frequent risk factors for PE were malignancy (38%) and immobility for > 4 days (28%). To our knowledge, this is the most recent study on VTE risk in an African population.
Evidence-based consensus guidelines for VTE prophylaxis have been available for almost 20 years . The ACCP guidelines recommend prophylaxis for patients at moderate-to-high risk of VTE, using either mechanical prophylaxis and/or pharmacological prophylaxis (LMWH, fondaparinux and UFH) . New oral anticoagulants are available in western countries, even if they have not yet shown their superiority and safety against LMWH in diverse situations. However, prophylaxis with these new oral anticoagulants must only be given in labelled indications (total hip arthroplasty and total knee arthroplasty).
Despite this evidence and the guidelines, physicians often fail to use this important therapy in a variety of high-risk situations, including the perioperative period, during critical illness and among other high-risk medical patients .
On the basis of the ENDORSE study methodology , a multidisciplinary group of Senegalese experts (the TROMBUS committee) conducted a country-wide assessment of the prevalence of VTE risk and VTE prophylaxis coverage in the acute-care setting in Senegal. The aim of the survey was to acquire accurate prospective data on VTE risk and VTE prophylaxis in developing countries to support national disease management.
Methods
The methodology was adapted from the ENDORSE study . Hospitals were considered eligible for enrolment if they contained more than 50 beds: in Senegal, this amounted to 18 functioning hospitals and private clinics with a total of 2084 eligible beds. Stratified sampling was done to ensure that at least two hospitals were included from each of the four geographic zones identified in the country. Included hospitals were randomly selected using a random table. At hospital level, wards were eligible if they were occupied by acute medical and surgical patients. All eligible wards within enrolled hospitals were included in the study.
To comply with the international ENDORSE study, the following wards were not included: psychiatric; paediatric; palliative; maternity and obstetric; neonatal; burns units; ophthalmologic; ear, nose and throat; dermatologic; alcohol/drug treatment; rehabilitation; accident and emergency.
In eligible wards, the inclusion criteria for patients were the same as for the ENDORSE study : age ≥ 40 years in medical wards or age ≥ 18 years in surgical wards. In medical wards, eligible patients included those who were acutely ill; in surgical wards, eligible patients included those who had undergone a surgical intervention requiring general or epidural anaesthesia for at least 45 mins or who were admitted due to a major trauma.
Patients were not eligible if they would have normally been admitted to an ineligible ward, if they were admitted for treatment of VTE or for a minor procedure, if their chart was unavailable or missing or if they refused to give informed consent. All patients in all eligible wards were screened.
Data collection
After obtaining informed consent from patients, data were collected using a standardized questionnaire adapted from the ENDORSE study case report form. Data collected included: patient demographics; date of admission; medical history, including risk factors for VTE; surgical intervention; risk factors for bleeding during hospitalization; risk factors for VTE manifested immediately before admission or in the first 14 days of hospitalization; type, dose and frequency of VTE prophylaxis and start or stop date; presence or absence of anticoagulation therapy and start or stop date; and condition of patient upon discharge.
Enrolled patients were assessed for VTE risk as per the ACCP 2004 guidelines ( , web tables 1 and 2). Patients considered as being at risk of VTE were classified as being at moderate, high or highest risk.
Types and use of VTE prophylaxis received by patients were recorded from their hospital charts. Evaluation of prophylaxis was done according to both the type and the dose prescribed. Patients were classified as receiving prophylaxis if a predefined prophylaxis method was prescribed by a physician during hospitalization. Prophylaxis methods included antithrombotic drugs (heparins, vitamin K antagonists, direct thrombin inhibitors, factor Xa inhibitors) given for prevention of DVT and PE or mechanical prophylaxis (intermittent pneumatic compression, graduated compression stockings, foot pump).
Clinical situations defined as contraindications to anticoagulant prophylaxis were: intracranial haemorrhage; hepatic impairment; bleeding at hospital admission; active gastroduodenal ulcer; or known bleeding disorder .
Statistical analysis
To assess the true occurrence of VTE risk at 10% with a margin of error of 4%, a minimum of 216 patients per analysis group were required.
Collected data were double checked and double entered into Epi Info software, version 6.04. Quantitative data were summarized using the median. Categorical data were summarized using number and percentage. Ninety-five percent CI were calculated.
The proportion of at-risk patients was calculated as the number of patients at moderate, high or highest risk of VTE/number of patients included. The proportion of patients receiving prophylaxis was calculated as the number of patients who received a prescription for prophylaxis/number of patients at risk of VTE.
The study was approved by the Senegalese Ethics Committee (Ministry of Health).
Results
Between October 2008 and November 2008, 943 patients were screened and of these 520 were enrolled for VTE risk assessment in 12 hospitals across Senegal; 306 of these patients were enrolled in Dakar and 214 from the surrounding regions. The number of beds assessed and the reasons for exclusion of patients are shown in Fig. 1 . Demographics and reasons for admission of patients are shown in Table 1 . The median age of patients on medical wards was 62 years, 150 (54.0%) were men and the median duration of hospitalization was 7 days. The median age of patients on surgical wards was 49 years, 155 (55.8%) were men and the median duration of hospitalization was 8 days.
