Combined oral contraceptives containing drospirenone appear to carry a three-fold higher risk of non-fatal idiopathic venous thromboembolism (VTE) than those containing levonorgestrel, although the overall risk is still low. The study used data from the UK General Practice Research Database (GPRD) that gathers information from a large number of general practices and more than three million people in the UK, including demographic data, information about prescribed drugs, diagnoses, hospital admissions and deaths. [With external links to the current evidence base]