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Table 2 Handling of missing data in primary analysis among 73 trials who reported missing outcome data

From: Handling missing data in RCTs; a review of the top medical journals

  N (%)1
Proportion of patients with missing outcome1  
 No missing data 4 (5)
 0 – 1% 2 (3)
 1 – 5% 11 (14)
 5 – 10% 24 (31)
 > 10% 36 (47)
Reported number of patients with missing outcomes by randomized treatment arm 71 (97)
Reported reasons why missing 66 (90)
Mentioned attempts to avoid missing data before and during trial 26 (36)
Methods  
 Complete case 33 (45)
 Simple imputation  
 Linear interpolation 3 (5)
 Worst-case 8 (11)
 LOCF 9 (12)
 Multiple imputation 6 (8)
 Model based  
 GEE (un-weighted) 3 (4)
 Mixed model/hierarchical/multilevel 11 (15)
  1. 1The denominator for the proportion of patients with missing outcome is 77; the other denominators are 73 (the number of studies with any missing data).