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Table 1 Amount of covariates missing values among subjects with missing outcome and those without missing outcome

From: Association between dietary polyphenols intake and an oxidative stress biomarker: interest of multiple imputation for handling missing covariates and outcomes

  Missing outcome (TBARS)    Available outcome (TBARS)   
  n = 2,013 n = 2,116
Covariates introduced in the imputation models (n = 37)a Total of subjects included (covariates all measured) Total of subjects excluded due to missing covariates % of missing values Total of subjects included (covariates all measured) Total of subjects excluded due to missing covariates % of missing values
Potential predictorsb
 Gender 2,013 0 0 2,116 0 0
 Age 2,013 0 0 2,116 0 0
 Intervention group 2,013 0 0 2,116 0 0
 Number of dietary records 2,013 0 0 2,116 0 0
 Energy intake 2,013 0 0 2,116 0 0
 Weight at inclusion 1,999 14 0.7 2,093 23 1.1
 Height at inclusion 1,999 14 0.7 2,089 27 1.3
 Zinc 1,952 61 3.1 2,024 92 4.5
 Smoking status at inclusion 1,951 62 3.2 2,045 71 3.5
 Selenium 1,944 69 3.5 2,024 92 4.5
 Alcohol intake at inclusion 1,875 138 7.4 1,976 140 7.1
 Alpha-tocophérol 1,729 284 16.4 1,824 292 16.0
 Beta carotene 1,729 284 16.4 1,824 292 16.0
 Retinol levels 1,729 284 16.4 1,824 292 16.0
 Vitamin C 1,651 362 21.9 1,441 675 46.8
Total 1,279 734   1,112 1,004  
Number of missing values
 1   391 19.4   617 29.2
 2   47 2.3   71 3.4
 3   268 13.3   276 13.0
  > 5   28 1.4   40 1.9
Auxiliary covariates
 Years of inclusion 2,013 0 0 2,116 0 0
 Physical activity at inclusion 1,975 38 1.9 2,081 35 1.7
 Educational level 1,979 34 1.7 2,080 36 1.7
 Smoking status at SU.VI.MAX2 2,000 13 0.7 2,095 21 0.01
Total 1,112 901     
  1. aBeside the 15 predictive covariates included in the analysis (and thus in the imputation model) and the 4 auxiliary covariates only included in the imputation model, the imputation model also included the 17 subclasses of polyphenols (with no missing value) and the outcome (TBARS)
  2. bCovariates included in the analysis model (n = 15)