Abdul Sultan, A, West, J, Stephansson, O, Grainge, MJ, Tata, LJ, Fleming, KM, Humes, D and Ludvigsson, JF (2015) Defining venous thromboembolism and measuring its incidence using Swedish health registries: a nationwide pregnancy cohort study. BMJ Open, 5 (11). e008864-e008864. ISSN 2044-6055

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Abstract

OBJECTIVE: To accurately define venous thromboembolism (VTE) in the routinely collected Swedish health registers and quantify its incidence in and around pregnancy. STUDY DESIGN: Cohort study using data from the Swedish Medical Birth Registry (MBR) linked to the National Patient Registry (NPR) and the Swedish Prescribed Drug Register (PDR). SETTING: Secondary care centres, Sweden. PARTICIPANT: 509,198 women aged 15-44 years who had one or more pregnancies resulting in a live birth or stillbirth between 2005 and 2011. MAIN OUTCOME MEASURE: To estimate the incidence rate (IR) of VTE in and around pregnancy using various VTE definitions allowing direct comparison with other countries. RESULTS: The rate of VTE varied based on the VTE definition. We found that 43% of cases first recorded as outpatient were not accompanied by anticoagulant prescriptions, whereas this proportion was much lower than those cases first recorded in the inpatient register (9%). Using our most inclusive VTE definition, we observed higher rates of VTE compared with previously published data using similar methodology. These reduced by 31% (IR=142/100,000 person-years; 95% CI 132 to 153) and 22% (IR=331/100,000 person-years; 95% CI 304 to 361) during the antepartum and postpartum periods, respectively, using a restrictive VTE definition that required anticoagulant prescriptions associated with diagnosis, which were more in line with the existing literature. CONCLUSIONS: We found that including VTE codes without treatment confirmation risks the inclusion of false-positive cases. When defining VTE using the NPR, anticoagulant prescription information should therefore be considered particularly for cases recorded in an outpatient setting.

Item Type:	Article
Uncontrolled Keywords:	HAEMATOLOGY; OBSTETRICS
Subjects:	R Medicine > RG Gynecology and obstetrics
Divisions:	Public Health Institute
Publisher:	BMJ Publishing
Related URLs:	Author
Date Deposited:	19 May 2016 10:46
Last Modified:	04 Sep 2021 12:55
DOI or ID number:	10.1136/bmjopen-2015-008864
URI:	https://researchonline.ljmu.ac.uk/id/eprint/3625

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