The Identification and Validation of Neural Tube Defects in the General Practice Research Database
THE IDENTIFICATION AND VALIDATION OF NEURAL TUBE DEFECTS IN THE GENERAL PRACTICE RESEARCH DATABASE Scott T. Devine A dissertation submitted to the faculty of the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Public Health (Epidemiology). Chapel Hill 2007 Approved by Advisor: Suzanne West Reader: Elizabeth Andrews Reader: Patricia Tennis Reader: John Thorp Reader: Andrew Olshan © 2007 Scott T Devine ALL RIGHTS RESERVED - ii- ABSTRACT Scott T. Devine The Identification And Validation Of Neural Tube Defects In The General Practice Research Database (Under the direction of Dr. Suzanne West) Background: Our objectives were to develop an algorithm for the identification of pregnancies in the General Practice Research Database (GPRD) that could be used to study birth outcomes and pregnancy and to determine if the GPRD could be used to identify cases of neural tube defects (NTDs). Methods: We constructed a pregnancy identification algorithm to identify pregnancies in 15 to 45 year old women between January 1, 1987 and September 14, 2004. The algorithm was evaluated for accuracy through a series of alternate analyses and reviews of electronic records. We then created electronic case definitions of anencephaly, encephalocele, meningocele and spina bifida and used them to identify potential NTD cases. We validated cases by querying general practitioners (GPs) via questionnaire. Results: We analyzed 98,922,326 records from 980,474 individuals and identified 255,400 women who had a total of 374,878 pregnancies. There were 271,613 full-term live births, 2,106 pre- or post-term births, 1,191 multi-fetus deliveries, 55,614 spontaneous abortions or miscarriages, 43,264 elective terminations, 7 stillbirths in combination with a live birth, and 1,083 stillbirths or fetal deaths.
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