IMPROVE VTE risk score and modified IMPROVE VTE risk score

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 [1], which has been externally validated [2].

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 [1]. 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 [3]. 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 [4]. That analysis showed that modified IMPROVE VTE score with an elevated D-dimer identified a subpopulation with about 3 fold higher VTE risk.


  1. Spyropoulos AC, Anderson FA Jr, FitzGerald G, Decousus H, Pini M, Chong BH, Zotz RB, Bergmann JF, Tapson V, Froehlich JB, Monreal M, Merli GJ, Pavanello R, Turpie AGG, Nakamura M, Piovella F, Kakkar AK, Spencer FA; IMPROVE Investigators. Predictive and associative models to identify hospitalized medical patients at risk for VTE. Chest. 2011 Sep;140(3):706-714.
  2. Rosenberg D, Eichorn A, Alarcon M, McCullagh L, McGinn T, Spyropoulos AC. External validation of the risk assessment model of the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) for medical patients in a tertiary health system. J Am Heart Assoc. 2014 Nov 17;3(6):e001152.
  3. Spyropoulos AC, Ageno W, Albers GW, Elliott CG, Halperin JL, Hiatt WR, Maynard GA, Steg PG, Weitz JI, Suh E, Spiro TE, Barnathan ES, Raskob GE; MARINER Investigators. Rivaroxaban for Thromboprophylaxis after Hospitalization for Medical Illness. N Engl J Med. 2018 Sep 20;379(12):1118-1127.
  4. Spyropoulos AC, Lipardi C, Xu J, Peluso C, Spiro TE, De Sanctis Y, Barnathan ES, Raskob GE. Modified IMPROVE VTE Risk Score and Elevated D-Dimer Identify a High Venous Thromboembolism Risk in Acutely Ill Medical Population for Extended Thromboprophylaxis. TH Open. 2020 Mar 13;4(1):e59-e65.