title: Limitations in Using Multiple Imputation to Harmonize Individual Participant Data for Meta-Analysis.
abstract: Individual participant data (IPD) meta-analysis is a meta-analysis in which the individual-level data for each study are obtained and used for synthesis. A common challenge in IPD meta-analysis is when variables of interest are measured differently in different studies. The term harmonization has been coined to describe the procedure of placing variables on the same scale in order to permit pooling of data from a large number of studies. Using data from an IPD meta-analysis of 19 adolescent depression trials, we describe a multiple imputation approach for harmonizing 10 depression measures across the 19 trials by treating those depression measures that were not used in a study as missing data. We then apply diagnostics to address the fit of our imputation model. Even after reducing the scale of our application, we were still unable to produce accurate imputations of the missing values. We describe those features of the data that made it difficult to harmonize the depression measures and provide some guidelines for using multiple imputation for harmonization in IPD meta-analysis.
authors.affiliation: Department of Preventive Medicine, Northwestern University, 680 N. Lake Shore Dr., Suite 1400, Chicago, IL, 60611, USA. siddique@Northwestern.edu.
authors.forename: Juned
authors.identifier: 0000-0002-1501-4152
authors.initials: J
authors.lastname: Siddique
authors.affiliation: Department of Preventive Medicine, Northwestern University, 680 N. Lake Shore Dr., Suite 1400, Chicago, IL, 60611, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: de Chavez
authors.affiliation: Department of Psychology, George Washington University, Washington, DC, USA.
authors.forename: George
authors.initials: G
authors.lastname: Howe
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, IL, USA.
authors.forename: Gracelyn
authors.initials: G
authors.lastname: Cruden
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, IL, USA.
authors.forename: C Hendricks
authors.initials: CH
authors.lastname: Brown
mesh_terms: D000293:Adolescent; D015982:Bias; D000077558:Big Data; D002648:Child; D000078332:Data Analysis; D003863:Depression; D005260:Female; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D035842:Research Subjects / Q000706:statistics & numerical data
keywords: Data synthesis; Individual participant data meta-analysis; Multiple imputation; Posterior predictive checking