Pattern of venous thromboembolic diseases in a resources-limited setting in Cameroon

Introduction: Admission for a medical illness is associated with an increased risk of venous thrombo-embolism; however reports addressing at this issue are rare in Cameroon. We sought to assess the pattern of thrombo-embolism among in-medical patients of a semi-urban hospital. Methods: We prospectively included 79 hospitalized medical patients of the Military Hospital of Bamenda (north-west region-Cameroon). From July 2010 and December 2013, we collected baseline demographic data, risk factors of venous thromboembolism, clinical presentation, diagnostic process and treatment. Results: In the 1445 patients admitted for medical illnesses, a total of 79 venous thrombo-embolic diseases were detected (55 deep vein thrombosis, 14 pulmonary embolism, 9 post-phlebitic syndrome and 1 cerulae alba dolens). The leading risk factors were prolonged immobilization (100%), age > 40 years (78.9%), obesity (43%), long distance travel (30.4%) and HIV-AIDS (21.5%). Thirty one (40.5%) had ≤ 2 cumulative risk factors, and 8 (10.1%) more than 4. All the patients in the group had a significant risk of deep vein thrombosis: 5 (6.3%), 34 (43%) and 40 (50.6%) with moderate, high and very high risk respectively. Increasing number of deep vein thrombosis was associated with increasing level of the risk and the clinical probability scores. Lower limb location of deep vein thrombosis was the most frequent with 75 (94.9%) cases. Almost all the patients received appropriate therapy with heparin and oral anticoagulant during their hospital stay. The mean length of hospital stay was 17.5 +/-15 (range 462) days; disability and death occurred in 15 (19%) and 17 (21.5%) respectively. Conclusion: Venous thromboembolism is also a common concern in a semi-urban practice of our country. Long distance travel, one of the leading risk factors merits to be more specifically studied. Pan African Medical Journal. 2016; 23:236 doi:10.11604/pamj.2016.23.236.7034 This article is available online at: http://www.panafrican-med-journal.com/content/article/23/236/full/ © Joseph Pierre Abah et al. The Pan African Medical Journal ISSN 1937-8688. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pan African Medical Journal – ISSN: 19378688 (www.panafrican-med-journal.com) Published in partnership with the African Field Epidemiology Network (AFENET). (www.afenet.net) Research Open Access


Introduction
As reported in Western countries, venous thromboembolism (VTE) is now a well-established major concern among in-patients in subsaharian Africa [1][2][3]. Venous thromboembolism includes deep vein thrombosis (DVT) and its acute complication, pulmonary embolism.
Although their cause is still unknown, the Virchow triad of venous stasis, hypercoagulability and endothelial injury, permits to define risk factors of these affections. Studies have established that VTE is a multifaceted disease [4]. In both surgical and medical wards, these risk factors accumulate, increasing the incidence of VTE, and worsening the prognosis of in-patients (morbidity, disability, impaired recovery and mortality). Unfortunately, because of missed or delayed diagnosis, the true incidence of VTE remains unknown, especially in medical wards [5,6]. Consequently, it is still underestimated among medically-ill patients. It is estimated that only 16% to 33% of such patients receive thromboprophylaxis as compared to up to 90% of at-risk surgical patients [7][8][9]. In Cameroon, there is scarcity of studies, all conducted in reference hospitals in an urban area, that have assessed risk factors (mainly clinical and environmental), prevention and treatment of VTE [1,10].
Hence, we sought to study, in a semi-urban and rural hospital setting, the pattern of VTE in terms of risk factors, clinical presentation, diagnostic process and treatment.

Design and setting
This cross-sectional study was carried out in Military Hospital of Bamenda from the 1st July 2010 to the 31st December 2013.
Physicians of the so-called hospital were among the most aware of the VTE risk in this semi-urban region of Cameroon. The estimated 1.500 000 inhabitants of the Region was made of public servants, students, farmers, livestock farmers and traders. Daily, they tackled uncomfortable trips in overloaded old cars, going round bad roads for long hours to join the nearer town or village. In the other hand, health facilities were both under-equipped and of very limited access. Hence, efficacious involvement for prevention, diagnosis and treatment of VTE could hardly been achieved.

Patients
We included consecutive adults aged 18 years or above. The patients were ill with a diagnosis of DVT and/or PE at or during their hospitalization. The ethics committee of the medical region approved the study protocol, and an informed consent was obtained from each patient (or a family member) prior to enrollment.

Data collection
Data were collected using a pre-designed questionnaire. They  [11,12]: Risk factors weighting 5 points (stroke < 1 month), 3 points (age of 75 years or more, prior VTE); 2 points (age 60 to 74 years, cancer, immobilization with a plaster, patient confined to bed for 72 hours or more, central venous access); and the 1 point (age 40 to 60, obesity, bed rest, varicosise, acute heart failure, sepsis, serious lung disease, acute myocardial infarction, inflammatory bowel disease, hormone-replacement therapy, oral contraceptive). A cumulative score of 0-1 defined a low risk, 2 a moderate risk, 3-4 a high risk and 5 or more a highest risk of VTE. Even though it is not included in this scaling risk score, we also considered long distance travel, defined as a trip of 4 hours or more, by car, plane, train or ship. Thereafter, a general clinical exam was conducted, taking in symptoms and detailed examination of the lower limbs, the respiratory and cardiovascular systems to search for signs of DVT and PE. The clinically suspicious DVT and PE were scaled by wellknown probability scores [13][14][15]. For DVT, the Wells' score of DVT: low probability for a score of 0 or less; intermediate probability for a score of 1 to 2; and the high probability for 3 and above. For PE, the Wells' score for PE (low probability between 0 to 1; intermediate probability between 2 to 6; and high probability for a score of 7 and more); and the reviewed Geneva score (low probability 0 to 3; Testing was positive for PE when an intravascular filling defect was present on one or more views of pulmonary artery branches.

Results
Of the overall 1445 patients admitted for a medical-illness during the 3 years of recruitment, 143 (9.9%) had a suspicion of VTE.

Discussion
Being a prospective study that enrolled consecutive patients admitted for medical illness, our population closely reflects the pattern of illness that a physician specialized in internal medicine may encounter in a typical semi-urban care unit. Thus as expected, our population consisted mostly of severely ill patients, and this may explain why many presented a wide spectrum of critical risk factors for VTE such as strokes, prior VTE and cancer; and these risk factors were commonly cumulative. Both high-to-highest risk of VTE cumulation of risk factors was associated with high frequency of VTE. Almost this same sharing in risk factors was found in some Page number not for citation purposes 4 other works in urban areas of sub-saharian Africa (SSA) [10,16,17]. Studies have well demonstrated an increased risk of VTE in the presence of multiple risk factors [11]. Even when there is an adequate thromboprophylaxis, incidence of VTE is still between 10 to 25% when risk factors cumulate [18,19]. Implication of HIV-AIDS in the occurrence of VTE was significant. This has been well demonstrated in many studies [20,21], and is just an increasing concern. Such a finding illustrates the burden of this infection and its opportunistic diseases in SSA. Long travel was among the most common risk factors in our study. Even though earlier studies demonstrated that it was a minor risk factor [22][23][24], we may mention it considering the travelling conditions in rural and semiurban areas of SSA. As reported by others, we found that obesity and age of ≥ 40 years were commonly present on patient with VTE [25,26]. Another re-statement was that scaling suspicious patient with a pretest probability score for DVT or PE, by increasing the predictive value of venous Doppler and CTPA, simplifies and improve the diagnostic process. This statement has clearly been made by Wells et al, and many other studies [13][14][15]. This conclusion is of great importance in SSA where diagnostic testing, when available, needs to be more accurately performed.
Furthermore, even if there are no recommendations on how to manage such cases, when pretest probability is high, it may be very useful to initiate an effective treatment in our area where tests are usually delayed or not performed. As malpractices in the diagnostic process, we noticed that all the patients with a suspicion of VTE could not undergo testing, some because of its cost and others when the scarce diagnostic tools had a breakdown, or the unique radiologist was absent. This situation most likely led to underdiagnosed VTE. Elsewhere, it was the D-dimers testing that could not be performed when indicated. Concordant prospective studies have clearly shown that D-dimers testing combined with pretest probability allows rapid and safe exclusion of VTE, preventing costly serial radiologic testing when the testing was negative [27,28].
Difficulties in the proper implementation of the diagnostic process of VTE are common in SSA and have been stated in some studies [10,29]. This highlights the under-equipment and low-access to health facilities in our area. Another reason is an insufficient number of specialists trained for management of VTE in medical wards. This emphasizes the need to increase the number of internists and radiologists in semi-urban areas of our country. Almost all the positive cases of VTE received appropriate therapy with low-weight molecular heparin, oral anticoagulant and non-pharmacological treatment. Mortality and disability are significant ensues among our population. It was cluster of some comorbidities and the worse evolution of VTE as such [30,31]. Our study has several limitations.
It showed concern only in the in-hospital treatment. The ambulatory compliance and follow-up is another important point that was not assessed here. Elsewhere it was conducted in only one hospital, even though there was exercising one of the scarce health team aware of the VTE risk in the area. This is reducing the global overview of the disease in our region.

Conclusion
Our study demonstrates that VTE remains a common condition in medical wards of a semi-urban hospital. Long distance travel is among the leading risk factors, and thus merits to be furthermore assessed. These results indicate a quick on the implementation of guidelines addressing the practice on these affections.

What is known about this topic
 Venous thromboembolism is a major health concern in sub-Saharan Africa, sharing the same trend as in western

Competing interests
The authors declare no competing interest.      These primary causes are not exclusive