IJCS | Volume 31, Nº5, September / October 2018

487 Pivatto Júnior et al. SAMe-TT 2 R 2 score forVTE patients? Int J Cardiovasc Sci. 2018;31(5)483-491 Original Article Table 1 - Demographic characteristics of the sample Variable n = 111 Sex, female 71 (64.0) Age (years) 54.1 ± 15.7 More than 2 comorbidities 16 (14.4) Hypertension 49 (44.1) Diabetes 20 (18.0) Previous stroke 10 (9.0) Renal disease 10 (9.0) Heart failure 9 (8.1) Coronary artery disease 7 (6.3) Pulmonary disease 6 (5.4) Peripheral artery disease 2 (1.8) Liver disease 1 (0.9) Thrombophilia 31 (27.9) Any cancer (current/previous) 25 (22.5) Race, non-white 12 (10.8) Tobacco use (within the past 2 years) 9 (8.1) Previous VTE 37 (33.3) Isolated DVT 29 (26.1) Isolated PE 5 (4.5) DVT + PE 3 (2.7) VTE on treatment Isolated DVT 78 (70.3) Isolated PE 23 (20.7) DVT + PE 10 (9.0) Initial heparin use (LMWH/UFH)* 82 (73.9) VTE: venous thromboembolism; DVT: deep vein thrombosis; PE: pulmonary embolism; LMWH: low-molecular-weight heparin; UFH: unfractionated heparin; (*) 14 (12.6%) patients without initial treatment data. Data are presented as number (%), mean ± standard deviation, or median (25-75 th percentile). Spanish study including 135 patients, 5 no differences were found in TTR between low- and high-risk patients (64.7 vs. 66.0%; p = 0.73), similar to our results. The score also had poor accuracy in the ROC curve analysis (c-statistic of 0.517 for TTR ≥ 65%). A study conducted in the United States involving 1,943 patients, excluding individuals with current/previous cancer, showed that, compared to a low SAMe-TT 2 R 2 score (0-1), a high score (> 2) was associated with both lower TTR (50 vs. 57%) and a higher proportion of patients with a TTR < 60% (63.4 vs. 52.3%; p < 0.0001). The SAMe-TT 2 R 2 score had a modest predictive ability for poor anticoagulation control (TTR < 60%) (c-statistic of 0.61), and its predictive performance did not change significantly at higher TTR cutoffs (0.65 for TTR < 65 and 70%). High-risk patients also had higher VTE recurrence rates and bleeding (7.9 vs. 4.5/100 patient-years; p = 0.002). 8 Taken together, these results demonstrate a modest agreement between the SAMe-TT 2 R 2 score and TTR, and only studies with large samples (n > 1,000 patients) were able to detect this association. This indicates that the score has limited clinical usefulness in patients with VTE. Moreover, its ability to predict TTR in this particular population was poor (c-statistic of 0.5 to 0.6). Our results are consistent with these findings, and a larger sample would probably allow greater statistical power to show this association, although without clinical applicability. Themost likely explanation for the difference observed between studies assessing the ability of the SAMe-TT 2 R 2 score to predict TTR in patients with AF and VTE is that patients with VTE are usually younger, make less frequent use of amiodarone, and have a lower prevalence of comorbidities, all of which are components of the score. In the study that developed the SAMe-TT 2 R 2 score, which included only patients with AF, 14.4% of patients in the internal validation cohort were < 60 years of age. 6 However, this age group accounted for 34.1 and 54.6% of patients with VTE included in the studies conducted by Palareti et al. 9 and Kataruka et al., 8 respectively. In the present study, the proportion of patients aged < 60 years (61.3%) was almost 4 times that of the original SAMe-TT 2 R 2 study. 6 Amiodarone was used by 0-1.1% of patients in VTE studies assessing the SAMe-TT 2 R 2 score, 5,8,9 while 12.7% of patients were receiving this drug in the original SAMe-TT 2 R 2 study. 6 Regarding comorbidities, previous stroke and heart failure were found in 12.8 and 19.3% of patients in the original SAMe- TT 2 R 2 study 6 against only 5.0-5.2% and 2.8-3.7% in VTE studies. 5,9 In addition, patients with VTE are more likely to have other comorbidities that are not included in the score, such as cancer. As pointed out by Rose et al. 30 in a case-control study, compared to matched controls, cancer patients receiving warfarin spend less time in the target PT/INR range, have more variable PT/INR values and more thrombotic events. Contributing factors may include drug interactions, fluctuations in dietary vitamin