Profile and anticoagulation outcomes of patients on warfarin therapy in an urban hospital in Cape Town, South Africa

BACKGROUND

Warfarin is the most frequently used oral anticoagulant worldwide and it is the oral anticoagulant of choice in South Africa for reducing thrombosis-related morbidity and mortality. However, the safety and efficacy of warfarin therapy depends mainly on careful monitoring and maintenance of the international normalised ratio (INR) within an optimal therapeutic range.

AIM

The aim of this study was to describe the profile and the anticoagulation outcomes of patients on warfarin therapy in a major warfarin clinic in the Western Cape Province of South Africa.

SETTING

Victoria Hospital - a district hospital in Cape Town.

METHODS

A cross sectional review of clinical records of patients on warfarin therapy who attended the INR clinic from 01 January 2014 to 30 June 2014 was done. Data analysis was done with STATA to generate appropriate descriptive data.

RESULTS

Our study showed that atrial fibrillation (AF) was the commonest indication for warfarin use in this study and hypertension was the commonest comorbidity among these patients. Only 48.5% achieved target therapeutic range; 51.5% were out-of-range. There was a significant association between alcohol consumption and poor anticoagulation outcomes (p-value < 0.022). Anticoagulation outcomes were better among the older age groups, male patients and in those with AF. The prevalence of thrombotic events while on warfarin treatment was 2.2%, while prevalence of haemorrhagic events was 14%. Most of the patients with bleeding events were on concurrent use of warfarin and other medications with potential drug interactions.

CONCLUSION

In our study, patients who achieved target therapeutic control were less than the acceptable 60%.

Venous thromboembolism among HIV-positive patients and anticoagulation clinic outcomes integrated within the HIV primary care setting

The purpose of this study was to explore factors associated with venous thromboembolism (VTE) among a cohort of HIV-infected patients and to describe early outcomes of warfarin anticoagulation therapy treated in a pharmacist-based anticoagulation clinic (ACC). A nested case-control study was conducted using the University of Alabama at Birmingham 1917 HIV Clinic Cohort. Conditional logistic regression was used to estimate factors associated with VTE. Among HIV-infected VTE cases, ACC-managed patients were compared to primary care provider (PCP)-managed patients to determine Time within Therapeutic INR Range (TTR). CD4 < 200 cells/µl (OR = 4.50; 95% CI = 1.52, 13.37; p = 0.007) and prior surgical procedures (13.20; 1.56; 111.4; p = 0.018) demonstrated positive associations with VTE, whereas longer HIV duration demonstrated a negative association (0.87; 0.78, 0.98; p = 0.019). TTR was 56.2% among ACC-managed patients compared to 30.5% of PCP-managed patients (p = 0.174). Overall, prior surgical procedures and low CD4 count were associated with an increased risk of VTE among HIV-infected patients. Despite small sample size, patients managed in ACC tend to achieve greater proportion of TTR compared to those managed by PCPs, suggesting that this model of therapy may provide additional benefits to HIV-infected patients.