2014, determined which groups of people, are most at risk for developing a clot during or after a long flight. the study focused on 8755 frequent flying employees from international companies and organizations. it found that travelers who have recently undergone a surgical procedure or who have a malignant disease such as cancer or who are pregnant are most at risk. preventative measures before flying may be taken in these at-risk groups as a solution. patients who have undergone kidney transplant have a high risk of developing rvt (about 0.4% to 6%). rvt is known to account for a large proportion of transplanted kidney failures due to technical problems (damage to the renal vein), clotting disorders, diabetes, consumption of ciclosporin or an unknown problem. patients who have undergone a kidney transplant are commonly prescribed ciclosporin, an immunosuppressant drug which is known to reduce renal blood flow, increase platelet aggregation in the blood and cause damage to the endothelial tissue of the veins. in a clinical study conducted by the nuffield department of surgery at the oxford transplant centre, uk, transplant patients were given low doses of aspirin, which has a some anti-platelet activity. there is risk of bleeding in transplant patients when using anticoagulants like warfarin and herapin. low dosage of aspirin was used as an alternative. the study concluded that a routine low-dose of aspirin in kidney transplant patients who are also taking ciclosporin significantly reduces the risk of rvt development.