Modified SAMe-TT₂R₂ score for predicting the therapeutic range of digoxin

Area of Science:

• Pharmacology
• Cardiology
• Clinical Medicine

Background:

• Digoxin, a common treatment for atrial fibrillation (AF), has faced scrutiny due to associations with increased mortality, particularly when serum digoxin concentrations (SDC) are not within the therapeutic range.
• Understanding factors that predict SDC is crucial for optimizing digoxin therapy and patient safety.

Purpose of the Study:

• To evaluate the predictive capability of the SAMe-TT2R2 and modified SAMe-TT2R2 scores for identifying patients with serum digoxin concentrations outside the therapeutic range (oTR).
• To assess the clinical utility of these scores in managing digoxin therapy.

Main Methods:

• A retrospective analysis of 2418 patients treated with digoxin between 2008 and 2018 was conducted.
• Serum digoxin concentrations (SDC) were recorded, with levels <0.5 ng/ml or >1.2 ng/ml defined as out of the therapeutic range (oTR).
• Multivariable regression analyses were used to identify independent predictors of oTR.

Main Results:

• The modified SAMe-TT2R2 score, abnormal body mass index, and elevated white blood cell count were identified as independent predictors of oTR.
• A modified SAMe-TT2R2 score greater than 3 demonstrated high predictive value for oTR, with 86% sensitivity and 65% specificity (AUC: 0.825).
• The modified SAMe-TT2R2 score showed a significant association with being out of the therapeutic range (OR: 4.19).

Conclusions:

• The modified SAMe-TT2R2 score is a valuable, independent predictor of out-of-therapeutic-range digoxin levels in patients with atrial fibrillation.
• This scoring system can assist clinicians in identifying patients at higher risk of suboptimal digoxin concentrations, potentially improving treatment outcomes.
• Despite mortality concerns, digoxin remains a relevant therapy, and tools like the modified SAMe-TT2R2 score can enhance its safe and effective use.