Defining venous thromboembolism and measuring its incidence using Swedish health registries: a nationwide pregnancy cohort study

Sultan, Alyshah Abdul, West, Joe, Stephansson, Olof, Grainge, Matthew J, Tata, Laila J, Fleming, Kate M ORCID: 0000-0002-6572-5016, Humes, David and Ludvigsson, Jonas F (2015) Defining venous thromboembolism and measuring its incidence using Swedish health registries: a nationwide pregnancy cohort study. BMJ OPEN, 5 (11). e008864-.

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Abstract

<h4>Objective</h4>To accurately define venous thromboembolism (VTE) in the routinely collected Swedish health registers and quantify its incidence in and around pregnancy.<h4>Study design</h4>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).<h4>Setting</h4>Secondary care centres, Sweden.<h4>Participant</h4>509,198 women aged 15-44 years who had one or more pregnancies resulting in a live birth or stillbirth between 2005 and 2011.<h4>Main outcome measure</h4>To estimate the incidence rate (IR) of VTE in and around pregnancy using various VTE definitions allowing direct comparison with other countries.<h4>Results</h4>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.<h4>Conclusions</h4>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:	Humans, Pregnancy Complications, Hematologic, Registries, Incidence, Risk Factors, Cohort Studies, Pregnancy, Adult, Sweden, Female, Venous Thromboembolism, Young Adult, Secondary Care
Depositing User:	Symplectic Admin
Date Deposited:	10 Oct 2017 13:15
Last Modified:	19 Jan 2023 06:53
DOI:	10.1136/bmjopen-2015-008864
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3009911