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Novel anticoagulants in an older and frail population with atrial fibrillation: the effect of inappropriate dosing on clinical outcomes

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Key summary points

AbstractSection Aim

To evaluate the proportion of patients underdosed (prescribed a reduced dose despite lack of indication) with a novel oral anticoagulant (NOAC) in an older and frail population with atrial fibrillation (AF).

AbstractSection Findings

Around half (51%) of patients received a reduced dose despite lacking formal criteria for dose reduction. Adjusted combined stroke, systemic embolism and major bleeding event rate was higher in underdosed patients, but not adjusted survival.

AbstractSection Message

A very significant proportion of frail and older patients with AF remains under an inappropriately reduced-dosed NOAC, and these patients have a worse prognosis.

Abstract

Purpose

An individualized approach should be taken regarding the use of novel oral anticoagulants (NOAC) in frail and older patients with atrial fibrillation (AF). We hypothesized that there would be a high proportion of underdosed patients among an older and frail population, where bleeding risk is higher.

Methods

We retrospectively analyzed patients admitted to an Internal Medicine ward with a previous diagnosis of AF and discharged with a NOAC (n = 327). We compared survival and incidence of dosing-related events (stroke, systemic embolism, and major bleeding) at 1-year between inappropriately underdosed patients (dose reduction without a formal indication) and the rest of the population.

Results

A total of 167 patients (51%) received a reduced dose despite lacking formal criteria for dose reduction. Before adjustment, underdosed patients, in comparison with non-underdosed patients, had a higher mortality at 1 year (HR = 1.6, 95% CI 1.2–2.1, p = 0.003) and a higher combined stroke, systemic embolism, and major bleeding event rate at 1-year (HR = 3.2, 95% CI 1.3–8.0, p = 0.015). After adjustment, combined stroke, systemic embolism, and major bleeding event rate was higher in underdosed patients (HR 3.7, 95% CI 1.1–12.3, p = 0.030), but survival was not different in the adjusted model (HR 1.4, 95% CI 0.9–2.1, p = 0.110).

Conclusions

Underdosed patients have a significant survival disadvantage and this may be due to clinician prescription bias, since this difference does not remain after adjusting for confounders. Combined stroke, systemic embolism, and major bleeding event rate was higher in underdosed patients.

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Authors and Affiliations

  1. Department of Cardiology, Coimbra University Hospital, Coimbra, Portugal

    José Paulo Henriques Cabral Lopes de Almeida, Ana Sofia Martinho, James Milner, Maria João Vidigal Ferreira, Rui Terenas Baptista & Lino Gonçalves

  2. Department of Medicine, Coimbra University Hospital, Coimbra, Portugal

    Adriana Girão & Armando Carvalho

  3. Department of Medicine, Figueira da Foz Hospital, Figueira da Foz, Portugal

    Ivo Barreiro

  4. Faculty of Medicine of Coimbra University, Coimbra, Portugal

    Maria João Vidigal Ferreira, Armando Carvalho, Rui Terenas Baptista & Lino Gonçalves

Authors
  1. José Paulo Henriques Cabral Lopes de Almeida
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  2. Ana Sofia Martinho
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  3. Adriana Girão
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  4. Ivo Barreiro
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  5. James Milner
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  6. Maria João Vidigal Ferreira
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  8. Rui Terenas Baptista
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  9. Lino Gonçalves
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Corresponding author

Correspondence to José Paulo Henriques Cabral Lopes de Almeida.

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None of the authors has any conflicts of interest to declare.

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All the data were collected and treated in accordance with the ethical standards of the institutional and with the 1964 Helsinki Declaration and its later amendments, fully respecting the anonymity of the patients.

Informed consent

Given the retrospective non-interventional design of the study and the full anonymization of patient data, informed consent was waived.

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de Almeida, J.P.H.C.L., Martinho, A.S., Girão, A. et al. Novel anticoagulants in an older and frail population with atrial fibrillation: the effect of inappropriate dosing on clinical outcomes. Eur Geriatr Med 11, 813–820 (2020). https://doi.org/10.1007/s41999-020-00343-w

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  • DOI: https://doi.org/10.1007/s41999-020-00343-w

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