| Type of studies |  | |
---|---|---|---|
Characteristics reported | Trials | Observational studies | All studies |
 | N (%)* | N (%)* | N (%)* |
 | (n = 73) | (n = 30) | (n = 103) |
Imputation details | Â | Â | Â |
Any imputation details provideda | 60 (82) | 27 (90) | 87 (85) |
Imputation method stated | 29 (40) | 9 (30) | 38 (37) |
    MI using chained equations (MICE) | 14 | 6 | 20 |
    MI using multivariate normal model (MVNI)b | 7 | 1 | 8 |
    MI using predictive mean matching (PMM) | 1 | 0 | 1 |
    MI using regression-based imputationc | 4 | 1 | 5 |
    MI using MICE & PMMd | 1 | 1 | 2 |
    MI using propensity score | 1 | 0 | 1 |
    MI using propensity score or regression modellinge | 1 | 0 | 1 |
General procedure/command specified | 5 (7) | 2 (7) | 7 (7) |
    Proc MI | 4 | 1 | 5 |
    MI command | 0 | 1 | 1 |
    Model-based MIf | 1 | 0 | 1 |
    Imputation method inferred | 11 (15) | 10 (33) | 21 (20) |
    MICE (SAS- IVEware) | 1 | 2 | 3 |
    MICE (Stata- pre V11) | 1 | 2 | 3 |
    MICE (Multiple packageg) | 1 | 0 | 1 |
    MVNI (SAS- pre V9.3-imputed more than 1 variable) | 5 | 1 | 6 |
    MVNI (R-Amelia II) | 0 | 2 | 2 |
    MVNI (S-plus) | 2 | 0 | 2 |
    Regression-based imputation (SAS pre V9.3-imputed 1 categorical variable) | 1 | 3 | 4 |
Non-normal variables transformed prior to imputation | 6 (8) | 6 (20) | 12 (12) |
    Log transformationh | 4 | 4 | 8 |
    Logit transformation | 0 | 1 | 1 |
    General comment about applying normalising transformation | 2 | 1 | 3 |
Provided details on the variables included in the imputation model | 26 (36) | 13 (43) | 39 (38) |
    Included auxiliary variable(s) | 6 | 4 | 10 |
    Included interaction term(s) | 2 | 2 | 4 |
    Included auxiliary variable and interaction | 3 | 2 | 5 |
    No information provided on auxiliary variables and interaction terms | 15 | 5 | 20 |
Number of imputations | 28 (38) | 19 (63) | 47 (46) |
    ≤5 | 8 | 3 | 11 |
    10 | 6 | 3 | 9 |
    11-50 | 8 | 6 | 14 |
    100 | 4 | 6 | 10 |
    >100 | 2 | 1 | 3 |
Carried out diagnostic checks of the imputation modeli | 0 (0) | 2 (7) | 2 (2) |
Assessed differences between results obtained from CC/LOCF and MI in the text/tablej | 45 (62) | 17 (57) | 62 (60) |
Software details | Â | Â | Â |
Imputation software statedk,l | 51 (70) | 25 (83) | 76 (74) |
    SAS | 23 | 10 | 33 |
    Stata | 18 | 9 | 27 |
    R | 6 | 6 | 12 |
    Other packages (SOLAS, S-plus, SPSS) | 4 | 0 | 4 |
Analysis status of MI | Â | Â | Â |
MI used in the primary analysis | 26 (36) | 12 (40) | 38 (37) |
MI used as a secondary analysis | 47 (64) | 19 (63) | 66l (64) |
    Methods used for primary analysis if MI applied as a secondary analysis |  |  |  |
      Complete case analysis (CC)m,n | 43 | 19 | 62 |
      Last observation carried forward (LOCF) | 4 | 0 | 4 |
Sensitivity analysis following MI | 3 (4) | 0 (0) | 3 (3) |
    Pattern-mixture model approach | 1 | 0 | 1 |
    Selection model approach | 0 | 0 | 0 |
    Performed but the method not statedo | 2 | 0 | 2 |