IMPROVE VTE risk score and modified IMPROVE VTE risk score
IMPROVE (International Medical Prevention Registry on Venous Thromboembolism) score is a weighted VTE (Venous Thromboembolism) risk score designed for medically ill patients , which has been externally validated .
While formulating the IMPROVE VTE risk score, data from 15,156 medically ill patients were analyzed to find the cumulative incidence of VTE over a 3 month period after admission . Of the 184 patients who developed symptomatic VTE, 67 had lower extremity DVT (deep vein thrombosis) and 76 had pulmonary embolism. Weightage given was 3 points for previous VTE, 2 points for known thrombophilia, 2 points each for lower limb paralysis and cancer, and one point each for immobilization, intensive or coronary care unit stay and age above 60 years. A score of 2 or more during hospitalization was associated with higher overall and VTE related mortality.
MARINER trial of rivaroxaban for thromboprophylaxis after hospitalization for medical illness modified IMPROVE VTE score by including D-dimer values above twice the upper limit of normal. The trial enrolled patients if IMPROVE VTE score was 4 or more or a score 2 or 3 with elevated D-dimer . MAGELLAN study of rivaroxaban had shown efficacy but with excess bleeding. A subpopulation of the MAGELLEN study which had lower bleeding risk was retrospectively analyzed to check whether modified IMPROVE VTE model could identify a high risk VTE subgroup . That analysis showed that modified IMPROVE VTE score with an elevated D-dimer identified a subpopulation with about 3 fold higher VTE risk.