Why are outcomes different for registry patients enrolled prospectively and retrospectively? Insights from the global anticoagulant registry in the FIELD-Atrial Fibrillation (GARFIELD-AF)
European Heart Journal - Quality of Care and Clinical Outcomes. 2017-08-16; 4(1): 27-35
DOI: 10.1093/EHJQCCO/QCX030
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1. Eur Heart J Qual Care Clin Outcomes. 2018 Jan 1;4(1):27-35. doi:
10.1093/ehjqcco/qcx030.
Why are outcomes different for registry patients enrolled prospectively and
retrospectively? Insights from the global anticoagulant registry in the
FIELD-Atrial Fibrillation (GARFIELD-AF).
Fox KAA(1), Accetta G(2), Pieper KS(3), Bassand JP(4)(5), Camm AJ(6)(7),
Fitzmaurice DA(8), Kayani G(2), Kakkar AK(4)(9); GARFIELD-AF Investigators.
Author information:
(1)Centre for Cardiovascular Science, University of Edinburgh, Queen’s Medical
Research Institute, 47 Little France Crescent, Edinburgh EH16?4TJ, UK.
(2)Thrombosis Research Institute, Emmanuel Kaye Building, Manresa Road, London
SW3?6LR, UK.
(3)Duke Clinical Research Institute, 2400 Pratt St, Durham, NC 27705, USA.
(4)Thrombosis Research Institute, Emmanuel Kaye Building, Manresa Road, London
SW3 6LR, UK.
(5)University of Besançon, 1 Rue Claude Goudimel, Besançon 25000, France.
(6)Molecular and Clinical Sciences Research Institute, Cardiology Clinical
Academic Group, St George’s, University of London, Cranmer Terrace, London SW17
0RE, UK.
(7)Imperial College London, Kensington, London SW7 2AZ, UK.
(8)Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK.
(9)University of London, Gower St, Kings Cross, London WC1E 6BT, UK.
Comment in
Eur Heart J Qual Care Clin Outcomes. 2018 Jan 1;4(1):6-7.
Aims: Retrospective and prospective observational studies are designed to reflect
real-world evidence on clinical practice, but can yield conflicting results. The
GARFIELD-AF Registry includes both methods of enrolment and allows analysis of
differences in patient characteristics and outcomes that may result.
Methods and results: Patients with atrial fibrillation (AF) and ≥1 risk factor
for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or
prospectively (n = 5501) from 19 countries and then followed prospectively. The
retrospectively enrolled cohort comprised patients with established AF (for a
least 6, and up to 24 months before enrolment), who were identified
retrospectively (and baseline and partial follow-up data were collected from the
emedical records) and then followed prospectively between 0 and 18 months (such
that the total time of follow-up was 24 months; data collection December 2009 and
October 2010). In the prospectively enrolled cohort, patients with newly
diagnosed AF (≤6 weeks after diagnosis) were recruited between March 2010 and
October 2011 and were followed for 24 months after enrolment. Differences between
the cohorts were observed in clinical characteristics, including type of AF,
stroke prevention strategies, and event rates. More patients in the
retrospectively identified cohort received vitamin K antagonists (62.1% vs.
53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs. 4.2%).
All-cause mortality rates per 100 person-years during the prospective follow-up
(starting the first study visit up to 1 year) were significantly lower in the
retrospective than prospectively identified cohort (3.04 [95% CI 2.51-3.67] vs.
4.05 [95% CI 3.53-4.63]; P = 0.016).
Conclusion: Interpretations of data from registries that aim to evaluate the
characteristics and outcomes of patients with AF must take account of differences
in registry design and the impact of recall bias and survivorship bias that is
incurred with retrospective enrolment.
Clinical trial registration: http://www.clinicaltrials.gov. Unique identifier for
GARFIELD-AF (NCT01090362).
Published on behalf of the European Society of Cardiology. All rights reserved. ©
The Author 2017. For permissions please email: .
DOI: 10.1093/ehjqcco/qcx030
PMID: 28950344 [Indexed for MEDLINE]