Thromb Haemost 2020; 120(04): 692-701
DOI: 10.1055/s-0040-1701483
Stroke, Systemic or Venous Thromboembolism
Georg Thieme Verlag KG Stuttgart · New York

Derivation and Validation of a Prediction Model for Venous Thromboembolism in Primary Care

Francesco Dentali
1   Department of Internal Medicine, Hospital of Luino, ASST-Sette Laghi, University of Insubria, Varese, Italy
Andrea Fontanella
2   Department of Internal Medicine, Hospital “Buon Consiglio-Fatebenefratelli,” Naples, Italy
Alexander T. Cohen
3   Department of Haematological Medicine, Guy's and St Thomas' NHS Foundation Trust, King's College London, London, United Kingdom
Monica Simonetti
4   Health Search, Italian College of General Practitioners and Primary Care, Florence, Italy
Luca Parretti
5   Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Perugia, Italy
Ettore Marconi
4   Health Search, Italian College of General Practitioners and Primary Care, Florence, Italy
Damiano Parretti
6   Italian College of General Practitioners and Primary Care, Florence, Italy
Gualberto Gussoni
7   Clinical Research Department, FADOI Foundation, Milan, Italy
Mauro Campanini
8   Department of Internal Medicine, Hospital “Maggiore della Carità,” Novara, Italy
Giancarlo Agnelli
9   Department of Internal and Cardiovascular Medicine-Stroke Unit, Hospital “S. Maria della Misericordia,” University of Perugia, Perugia, Italy
Claudio Cricelli
6   Italian College of General Practitioners and Primary Care, Florence, Italy
4   Health Search, Italian College of General Practitioners and Primary Care, Florence, Italy
› Author Affiliations
Funding This study was funded by grants from AlfaSigma, which were not directly involved in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.
Further Information

Publication History

19 April 2019

24 December 2019

Publication Date:
14 April 2020 (online)


Background Most episodes of venous thromboembolism (VTE) occurred in primary care. To date, no score potentially able to identify those patients who may deserve an antithrombotic prophylaxis has been developed.

Aim The objective of this study is to develop and validate a prediction model for VTE in primary care.

Methods Using the Health Search Database, we identified a cohort of 1,359,880 adult patients between 2002 and 2013. The date of the first General Practitioner's (GP) visit was the cohort entry date. All VTE cases (index date) observed up to December 2014 were identified. The cohort was randomly divided in a development and a validation cohort. According to nested case-cohort analysis, up to five controls were matched to their respective cases on month and year of cohort entry and duration of follow-up.

The score was evaluated according to explained variance (pseudo R2) as a performance measure, ratio of predicted to observed cases as model calibration and area under the curve (AUC) as discrimination measure.

Results The score was able to explain 27.9% of the variation for VTE occurrence. The calibration measure revealed a margin of error lower than 10% in 70% of the population. In terms of discrimination, AUC was 0.82 (95% confidence interval: 0.82–0.83). Results of sensitivity analyses substantially confirmed these findings.

Conclusion The present score demonstrated a very good accuracy in predicting the risk of VTE in primary care. This score may be therefore implemented in clinical practice so aiding GPs in making decision on patients potentially at risk of VTE.

Authors' Contributions

All persons that contributed to this manuscript met the criteria for authorship and are listed as authors.

Supplementary Material

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