The prevalence of deep vein thrombosis and associated factors in adult medical patients admitted to the University Teaching Hospital,Lusaka,Zambia

Abstract

Deep vein thrombosis (DVT) and pulmonary embolism (PE) collectively referred to as venous thromboembolism (VTE) are a global concern with substantial morbidity and mortality. Symptomatic DVT commonly occur in hospitalized patients with acute medical illnesses. Thromboprophylaxis for DVT is not routinely given to hospitalized medical patients in most hospitals in Zambia. The purpose of this study was to determine the prevalence of DVT and associated factors in medical patients admitted to the University Teaching Hospital (UTH).The main objectives were: to determine the prevalence of DVT in medical patients admitted to the UTH for at least 7 days; document the anatomical distribution of DVT in medical patients admitted to the UTH; establish demographic and clinical characteristics of medical patients with DVT and finally determine the accuracy of the Well’s score for DVT in patients who develop DVT at UTH. We carried out a descriptive, cross sectional analytical study. The sample size comprised 296 medical patients admitted for at least 7 days. A questionnaire was used to obtain demographic characteristics and relevant clinical history. A focused detailed physical examination was done to screen for DVT of the lower limbs and Well’s score for DVT computed. Laboratory tests including HIV test and full blood count were done. Compression ultrasound scans (USS) were done on lower limbs of recruited patients to determine the presence of DVT. Variables of interest were compared by chi-square, Kruskal-Wallis and t-tests. Multivariate and univariate logistic regression analysis were used to assess for associations between DVT and independent variables of interest Prevalence of DVT was found to be 11.1 % (33/296). The prevalence of proximal lower limb DVT was 9.1 %( 27/296). Eighty two (27/33) percent of all patients with DVT had proximal lower limb DVT. The Mean age of patients with DVT was 42.12 years (SD 12.71) while mean hospital admission was 11.91 days (SD 7.77) days. Patients with primary diagnosis of infectious origin accounted for 67 % of all cases of DVT. Primary diagnosis of tuberculosis was the most common infection among patients with DVT accounting for 60.6 % of all infections. Of all patients with DVT, 69.7 % were HIV positive. xii The Wells score specificity for DVT was 73.4% while the sensitivity was 100%. The accuracy was 76.3%.The positive and negative predictive values were 32% and 100% respectively.The pre-test Wells score correlated well with the USS findings and could be used as a rule out test for those with suspected DVT. Proximal Lower limb DVT is common among HIV positive medical patients admitted for at least 7 days at the UTH. In our study, lower extremity proximal DVT was more common in patients with tuberculosis and a low BMI. Up to 85% of lower limb DVT was asymptomatic. Without a high index of suspicion, lower limb DVT is likely to be missed. The pretest Wells score correlated well with the USS findings .A follow up study to evaluate for genetic and biochemical factors that predispose to DVT need to be undertaken in the near future. There is need to advocate for thromboprophylaxis in medical patients with acute illness and prolonged hospital stay.