Validation of the Wells scoring scale for Deep Vein thrombosis in African patients
Background: Deep Venous thrombosis (DVT) is difficult to diagnose. Pre-test probability rules used in screening for DVT have not been validated in an African population.
Objective: Validation of the Wells Rule in African patients suspected to have DVT.
Design: Descriptive cross sectional study.
Setting: Moi Teaching and Referral Hospital (MTRH), a tertiary referral centre in Eldoret, Kenya
Subjects: Adult patients presenting with suspected DVT had their pre-test probability of DVT calculated using the Wells rule before undergoing compression ultrasound imaging of their legs to confirm the diagnosis.
Results: Ninety-seven (97) patients were enrolled between April 2010 and January 2011: median age 38 years (IQR: 31, 48); 71 (73%) women; and 40 (44%) were HIV-infected. DVT was confirmed in 78/81 (96%) of patients with high probability and 2/16 (12%) in those with low probability. Sensitivity of the Wells score was 0.975(95%CI 0.940,0.992) and specificity was 0.824 (95%CI 0.657, 0.902). Likelihood ratio for a positive test was 5.525(95%CI2.743, 10.097) and 0.030 (95%CI 0.009, 0.092) for a negative test. We found strong agreement between the Wells score and Doppler ultrasound findings with a Kappa value of 0.817 (95%CI 0.611, 0.915).
Conclusions: The Wells Rule has good sensitivity, specificity and likelihood ratios in the preliminary diagnosis of DVT in African patients.