SAMe-TT₂R₂ to Predict Clinical Outcomes and Time in Therapeutic Range in Patients on Vitamin K Antagonists: A Systematic Review and Meta-Analysis

Background: The SAMe-TT2R2 score identifies patients on vitamin K antagonists (VKAs) who are more likely to have poor time in therapeutic range (TTR); however, the association between SAMe-TT2R2 and clinical outcomes remains controversial. Objectives: The objective is to assess the association of SAMe-TT2R2 score with clinical outcomes and poor TTR in patients on VKAs. Methods: We searched using the term "SAMe-TT2R2." Original articles reporting clinical outcomes and SAMe-TT2R2 scores before October 2021 were included. Odds ratios (ORs) of clinical outcomes, diagnostic accuracy parameters of poor TTR (<60%-70%), and mean TTR were extracted. Meta-analysis was performed using random-effects models. Results: Ten studies were included (N = 22 894); 4 showed pooled changes in TTR of -3.61% (95% CI:-4.88% to -2.35%) and -3.98% (95% CI: -6.08% to -1.87%) at SAMe-TT2R2 scores >= 2 and >= 3, respectively, compared with lower scores. The diagnostic accuracy parameters for poor TTR were too heterogeneous to conclude. SAMe-TT2R2 >= 3 significantly correlated with all adverse events (OR = 1.43 [95% CI: 1.29-1.54; P < 0.001]), composite thromboembolism (OR = 1.53 [95% CI: 1.19-1.97; P = 0.001]), and composite bleeding (OR = 1.33 [95% CI: 1.12-1.59; P = 0.001] regardless of the indication, while an SAMe-TT2R2 >= 2 significantly correlated with mortality (OR = 1.32 [95% CI: 1.02-1.70; P = 0.033]). We found no relationship between an SAMe-TT2R2 >= 3 and mortality or between a score >= 2 and clinical outcomes. Conclusions and Relevance: Patients on VKAs with SAMe-TT2R2 >= 3 experienced more adverse events, bleeding, and thromboembolism compared with patients who had an SAMe-TT2R2 <3. However, the score had limited and inconclusive predictability for poor TTR in the study.