Values are reported as mean AE standard deviation or n (%). BMI, body mass index; CHA 2 DS 2 -VASc, Congestive heart failure; Hypertension; Age ≥ 75 years; Diabetes mellitus; prior Stroke, transient ischaemic attack or thromboembolism; Vascular disease; Age 65-74 years; Sex category, i.e., female; DOAC, direct oral anticoagulant; TIA: transient ischaemic attack; VKA: vitamin K antagonists. ª Additional supporting information may be found online in the Supporting Information section at the end of the article.Data S1. Study protocol: Vitamin K antagonist (VKA) therapy versus New Oral Anticoagulant (NOAC) therapy in patients with currently well controlled VKA therapy for nonvalvular atrial fibrillation: a pilot study.

BackgroundVitamin 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.ObjectivesTo evaluate the predictive value and clinical usefulness of the SAMe-TT2R2 score to identify those at risk for poor VKA control.MethodsWe 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.Results16 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).ConclusionThe 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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