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Approaches for combining primary care electronic health record data from multiple sources: a systematic review of observational studies

Dedman D, Cabecinha M, Williams R, Evans SJW, Bhaskaran K, Douglas IJ

BMJ open, 2020

Abstract

OBJECTIVE: To identify observational studies which used data from more than one primary care electronic health record (EHR) database, and summarise key characteristics including: objective and rationale for using multiple data sources; methods used to manage, analyse and (where applicable) combine data; and approaches used to assess and report heterogeneity between data sources.

DESIGN: A systematic review of published studies.

DATA SOURCES: Pubmed and Embase databases were searched using list of named primary care EHR databases; supplementary hand searches of reference list of studies were retained after initial screening.

STUDY SELECTION: Observational studies published between January 2000 and May 2018 were selected, which included at least two different primary care EHR databases.

RESULTS: 6054 studies were identified from database and hand searches, and 109 were included in the final review, the majority published between 2014 and 2018. Included studies used 38 different primary care EHR data sources. Forty-seven studies (44%) were descriptive or methodological. Of 62 analytical studies, 22 (36%) presented separate results from each database, with no attempt to combine them; 29 (48%) combined individual patient data in a one-stage meta-analysis and 21 (34%) combined estimates from each database using two-stage meta-analysis. Discussion and exploration of heterogeneity was inconsistent across studies.

CONCLUSIONS: Comparing patterns and trends in different populations,…

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