Can the Charlson comorbidity index help to guide DOAC dosing in patients with atrial fibrillation and improve the efficacy and safety of treatment? A subanalysis of the MAS study.

Background: Frailty influences the effectiveness and safety of anticoagulant therapy in patients with atrial fibrillation (AF). The age-weighted Charlson comorbidity index may offer a valuable tool to assess the risk of adverse events in AF patients treated with direct oral anticoagulants (DOACs). This sub-analysis of MAS trial data aimed to assess whether using the Charlson index, instead of the standard criteria, would have led to different dosing and improved adverse event occurrence during treatment.

Methods: The MAS study looked for a relationship between DOAC levels assessed at baseline and adverse events during follow-up. The study is described in detail elsewhere.

Results: Among the 1,657 patients studied, 832 (50.2 %) had a relatively low Charlson index (up to 6, general median class), of whom 132 (15.9 %) were treated with reduced doses. Conversely, among the 825 patients with a high Charlson index (≥7), 257 (31.1 %) received standard doses. A weak but statistically significant positive correlation (r = 0.1413, p < 0.0001 by ANOVA) was observed between increasing Charlson classes and DOAC levels standardized to allow comparability among drug results. However, no significant differences were found in the incidence or number of adverse events during follow-up, or in other parameters, between patients with low and high Charlson's scores.

Conclusions: Utilizing the Charlson index would have led to notable differences in DOAC dosing compared to standard criteria. However, we found no evidence that its use would have improved the prediction of adverse events in AF patients enrolled in the MAS study.