Anticoagulation prediction score for AF less useful in DVT patients

The SAMe-TT2R2 score for predicting adequate warfarin control in AF patients is less useful in the DVT setting, a Queensland study has found.

A Griffith University-led study of almost 600 patients in a warfarin care program  found no significant difference between the mean time in therapeutic range (TTR) in patients with a favourable SAMe-TT2R2 score of 0–1 compared to those with a score ≥2 typically linked to sub-optimal control.

However there was a significantly higher (p<0.0001) percentage of patients achieving a TTR ≥ 65% when categorised according to SAMe-TT2R2 score 0–1 (93.8%) versus a score ≥2 (69.2%).

The study authors said it was possible that, compared to AF patients, DVT patients had fewer comorbidities – a key component of the six-item SAMe-TT2R2 score.

And the study was unable to incorporate race – another component in the score due to polymorphisms which determine drug metabolism – as the study site did not collect that information.

However the relatively high mean TTR of 78% overall, and 78% versus 76% in the SAMe-TT2R2 groups respectively, was also a contributing factor.

Lead author Dr Nijole Bernaitis, from Griffith University’s School of Pharmacy, told the limbic the evidence suggested SAMe-TT2R2 score was not as useful in a centre with a high quality of warfarin control.

“Whereas in people with low TTR – we did a study in Singapore where they have a very low TTR of around 58% – SAMe-TT2R2 better differentiated patients regarding warfarin control.”

She noted dedicated warfarin care programs usually had a closer follow-up of patients and closer monitoring of factors such as medication changes which can influence TTR.

Dr Bernaitis said the SAMe-TT2R2 score was also becoming less useful as DOACs became more widely used.

“Now the DOACs are considered to be first line agents for many conditions but there are still some people that need to have warfarin either because of their kidney function or because, in AF patients, maybe they’ve got valvular disease.”

In these patients who start warfarin, the SAMe-TT2R2 score >2.0 could at least flag patients who might need increased follow-up.

The findings are published in the Journal of Thrombosis and Thrombolysis.

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