title: Multiple imputation of missing repeated outcome measurements did not add to linear mixed-effects models.
abstract: OBJECTIVE
  To assess the added value of multiple imputation (MI) of missing repeated outcomes measures in longitudinal data sets analyzed with linear mixed-effects (LME) models.
  
  
  METHODS
  Data were used from a trial on the effects of Rosuvastatin on rate of change in carotid intima-media thickness (CIMT). The reference treatment effect was derived from a complete data set. Scenarios and proportions of missing values in CIMT measurements were applied and LME analyses were used before and after MI. The added value of MI, in terms of bias and precision, was assessed using the mean-squared error (MSE) of the treatment effects and coverage of the 95% confidence interval.
  
  
  RESULTS
  The reference treatment effect was -0.0177 mm/y. The MSEs for LME analysis without and with MI were similar in scenarios with up to 40% missing values. Coverage was large in all scenarios and was similar for LME with and without MI.
  
  
  CONCLUSIONS
  Our study empirically shows that MI of missing end point data before LME analyses does not increase precision in the estimated rate of change in the end point. Hence, MI had no added value in this setting and standard LME modeling remains the method of choice.
authors.affiliation: Julius Center for Health Sciences and Primary Care, Stratenum 6.131, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. s.a.e.peters@umcutrecht.nl
authors.forename: Sanne A E
authors.initials: SA
authors.lastname: Peters
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Bots
authors.forename: Hester M
authors.initials: HM
authors.lastname: den Ruijter
authors.forename: Mike K
authors.initials: MK
authors.lastname: Palmer
authors.forename: Diederick E
authors.initials: DE
authors.lastname: Grobbee
authors.forename: John R
authors.initials: JR
authors.lastname: Crouse
authors.forename: Daniel H
authors.initials: DH
authors.lastname: O'Leary
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Evans
authors.forename: Joel S
authors.initials: JS
authors.lastname: Raichlen
authors.forename: Karel G M
authors.initials: KG
authors.lastname: Moons
authors.forename: Hendrik
authors.initials: H
authors.lastname: Koffijberg
mesh_terms: D000465:Algorithms; D050197:Atherosclerosis / Q000188:drug therapy / Q000473:pathology; D001699:Biometry; D059168:Carotid Intima-Media Thickness; D002986:Clinical Trials as Topic; D016001:Confidence Intervals; D005260:Female; D005464:Fluorobenzenes / Q000627:therapeutic use*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011743:Pyrimidines / Q000627:therapeutic use*; D012107:Research Design; D000068718:Rosuvastatin Calcium; D013449:Sulfonamides / Q000627:therapeutic use*
chemical_list: D005464:Fluorobenzenes; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011743:Pyrimidines; D013449:Sulfonamides; D000068718:Rosuvastatin Calcium