Research pointers: Risk of subsequent thromboembolism for patients with pre-eclampsia

Abstract

The study was approved by our research ethics board and took place in Ontario, Canada, where all hospital services are publicly funded. We used an administrative database that is based on anonymised populations and which records all hospitalisations from 1 April 1988 onwards. All discharges between 1 April 1990 and 1 January 1994 with a primary ICD-9 (international classification of diseases, 9th revision) code of pre-eclampsia, severe pre-eclampsia, eclampsia, or toxaemia were identified (see appendix A on bmj.com). These codes had a sensitivity of 89% (95% confidence interval 78% to 94%) and a specificity of 67% (79% to 94%) for patients with true pre-eclampsia (appendix B).