Key result
The SAMe-TT2R2 score ≥ 2 weakly predicted poor vitamin K antagonist control with a positive likelihood ratio of 1.25, providing too limited an effect to be clinically useful for individual patient decision-making.
Why the study?
Does the SAMe-TT2R2 score predict poor VKA control (TTR < 70%) in patients on VKA therapy?
Meta-Analysis (n=14,853)
Does the SAMe-TT2R2 score predict poor VKA control (TTR < 70%) in patients on VKA therapy?
Effect estimate: LR+ 1.25 (95% CI 1.14-1.38)
The SAMe-TT2R2 score has limited clinical utility for predicting poor VKA control in individual patients due to small effect sizes.
BACKGROUND: Vitamin K antagonist (VKA) therapy is safer and more effective when patients have a high time within the therapeutic range and low international normalised ratio variability. The SAMe-TT2R2 score aims to identify those at risk for poor VKA control. OBJECTIVES: To evaluate the predictive value and clinical usefulness of the SAMe-TT2R2 score to identify those at risk for poor VKA control. METHODS: We performed a systematic review in MEDLINE and Embase for original research papers assessing the SAMe-TT2R2's relation to poor TTR. We performed a meta-analysis where scores ≥ 2 and ≥ 3 predicting TTR < 70%. When studies evaluated other cutoffs for TTR or SAMe-TT2R2, they were harmonised by multiple simulations with patient characteristics from the individual studies, if the data were available. RESULTS: 16 studies were identified and used in the meta-analysis: 4 and 2 times directly, 8 and 8 times harmonised for scores ≥ 2 and ≥ 3, respectively (not all studies provided information about both cutoffs). The sensitivities and specificities were too heterogeneous to pool. The positive likelihood ratios were 1.25 (1.14-1.38) for a score ≥ 2, and 1.24 (1.09-1.40) for a score ≥ 3; the negative ones were 0.87 (0.82-0.93) and 0.96 (0.91-1.02), respectively. This shows that the post-test probabilities hardly differ from the prior probability (prevalence). CONCLUSION: The SAMe-TT2R2 score does predict low TTR, but the effect is small. Its effect on individual patients is too limited to be clinically useful.
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Miert et al. (2018) conducted a meta-analysis in Patients on Vitamin K antagonist (VKA) therapy (n=14,853). SAMe-TT2R2 score ≥ 2 vs. SAMe-TT2R2 score < 2 was evaluated on Time in therapeutic range (TTR) < 70% (LR+ 1.25, 95% CI 1.14-1.38). The SAMe-TT2R2 score ≥ 2 weakly predicted poor vitamin K antagonist control with a positive likelihood ratio of 1.25, providing too limited an effect to be clinically useful for individual patient decision-making.
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