Background
Methods
Databases
Imputation of missing stage information
1. Selection of variables
Breast cancer data set | Malignant melanoma data set | ||||
---|---|---|---|---|---|
Observed | Simulated* | Observed | Simulated* | ||
Number of cases | 21,428 | 17,162 | 5,520 | 1,685 | |
Sex (in %) | Female | 100 | 100 | 45.8 | 45.1 |
Male | 0 | 0 | 54.2 | 54.9 | |
Age | Median (1st and 3rd Quartile) | 62.0 (53.0; 71.0) | 61.0 (52.0; 69.0) | 61.0 (45.0; 70.2) | 59.0 (43.0; 68.0) |
T-stage (in %) | 1 | 47.3 | 49.2 | 36.9 | 36.9 |
2 | 34.0 | 34.3 | 11.8 | 12.4 | |
3 | 5.5 | 5.1 | 8.0 | 7.6 | |
4 | 7.3 | 5.7 | 4.7 | 4.4 | |
Unknown | 6.0 | 5.7 | 38.6 | 38.7 | |
N-stage (in %) | 0 | 53.4 | 55.1 | 29.5 | 32.5 |
1 | 25.4 | 25.2 | 1.7 | 1.4 | |
2 | 6.1 | 5.9 | 0.6 | 0.4 | |
3 | 3.7 | 3.5 | 0.2 | 0.1 | |
Unknown | 11.4 | 10.3 | 67.9 | 65.6 | |
M-stage (in %) | 0 | 77.9 | 80.8 | 31.0 | 33.5 |
1 | 5.6 | 3.7 | 2.2 | 0.7 | |
Unknown | 16.5 | 15.4 | 66.8 | 65.8 | |
UICC-stage (in %) | I | 32.0 | 29.7 | 23.9 | 7.4 |
II | 33.2 | 30.0 | 3.3 | 0.7 | |
III | 11.4 | 10.4 | 2.8 | 0.8 | |
IV | 5.6 | 3.7 | 0.5 | 0.7 | |
Unknown | 17.8 | 26.1 | 69.5 | 90.4 | |
Survival time (days) | Median (1st and 3rd Quartile) | 1279 (549; 2161) | 1279 (580; 2130) | 1552 (700; 2253) | 1765 (975; 2557) |
Censoring (in %) | Censored | 84.6 | 88.5 | 88.1 | 90.5 |
Year of diagnosis | 2000 | 10.2 | 9.7 | 10.8 | 15.1 |
2001 | 10.7 | 10.2 | 11.5 | 14.4 | |
2002 | 11.1 | 10.6 | 10.0 | 10.9 | |
2003 | 10.8 | 10.9 | 14.3 | 12.2 | |
2004 | 10.7 | 10.7 | 12.8 | 14.6 | |
2005 | 10.7 | 10.9 | 10.7 | 8.9 | |
2006 | 11.5 | 11.6 | 10.0 | 10.8 | |
2007 | 11.6 | 12.1 | 9.7 | 5.0 | |
2008 | 12.7 | 13.4 | 10.3 | 8.1 | |
Grading (in %) | 1 | 10.6 | 10.6 | 3.4 | 5.7 |
2 | 54.2 | 53.7 | 0.3 | 0.2 | |
3 | 30.0 | 30.1 | 0.2 | 0.2 | |
4 | 0.2 | 0.1 | < 0.1 | 0.1 | |
Unknown | 5.0 | 5.5 | 96.1 | 93.8 | |
Radiotherapy (in %) | Yes | 66.4 | 80.2 | 1.4 | 0.5 |
no | 17.8 | 15.3 | 52.2 | 64.5 | |
Unknown | 15.8 | 4.5 | 46.4 | 35.0 | |
Chemotherapy (in %) | Yes | 46.1 | 47.9 | 1.8 | 1.4 |
No | 37.4 | 36.7 | 51.8 | 63.9 | |
Unknown | 16.6 | 15.5 | 46.5 | 34.8 | |
Hormone therapy (in %) | Yes | 60.6 | 62.3 | 0.0 | 0.0 |
No | 19.1 | 18.1 | |||
Unknown | 20.3 | 19.6 | |||
Morphology (in %) | Infiltrating duct carcinoma | 69.0 | 70.6 | ||
Lobular carcinoma | 12.3 | 11.9 | |||
Infiltrating duct and lobular carcinoma | 7.4 | 7.9 | |||
Nodular melanoma | 12.4 | 13.6 | |||
Lentigo maligna melanoma | 5.3 | 5.1 | |||
Superficial spreading melanoma | 41.4 | 48.4 | |||
Others and NOS | 10.5 | 9.6 | 41.0 | 32.8 | |
Topography (in %) | Central portion of breast | 5.3 | 5.1 | ||
Upper-inner quadrant of breast | 9.3 | 9.6 | |||
Lower-inner quadrant of breast | 4.6 | 4.7 | |||
Upper-outer quadrant of breast | 35.7 | 36.3 | |||
Lower-outer quadrant of breast | 6.3 | 6.3 | |||
Axillary tail of breast | 0.2 | 0.1 | |||
Overlapping lesion of breast | 8.9 | 8.2 | |||
Trunc | 32.2 | 35.9 | |||
Extremity | 46.7 | 50.1 | |||
Head/Neck | 13.5 | 11.3 | |||
NOS | 29.9 | 29.7 | 7.6 | 2.7 |
2. Simulation of a breast cancer data set and a malignant melanoma data set
3. Specification of the imputation models
4. Creation of ten complete data sets out of each simulated data sets using multiple imputation
5. Statistical analysis and model evaluation
6. Sensitivity analyses for malignant melanoma
Software
Descriptive statistics
Results
Missing information
Simulated data sets
Accuracy of the imputations on individual level
Breast cancer | Malignant melanoma | |||||||
---|---|---|---|---|---|---|---|---|
PR (in %) | PMM (in %) | RF (in %) | Prop (in %) | PR (in %) | PMM (in %) | RF (in %) | Prop (in %) | |
T-stage | ||||||||
Concordance | 48.7 | 48.0 | 31.4 | 39.4 | 47.7 | 47.2 | 40.6 | 42.5 |
Dislocation by 1 stage | 37.8 | 38.4 | 55.4 | 41.5 | 32.0 | 32.3 | 30.8 | 31.0 |
Dislocation by 2 stages | 10.1 | 10.3 | 8.2 | 11.4 | 15.4 | 15.5 | 19.9 | 18.1 |
Dislocation by 3 stages | 3.4 | 3.4 | 5.0 | 7.7 | 4.9 | 5.0 | 8.7 | 8.4 |
UICC-stage | ||||||||
Concordance | 79.5 | 79.1 | 58.8 | 74.2 | 80.6 | 80.8 | 77.9 | 79.5 |
Dislocation by 1 stage | 17.3 | 17.6 | 25.0 | 19.9 | 11.1 | 10.8 | 13.3 | 11.5 |
Dislocation by 2 stages | 2.9 | 2.9 | 14.2 | 4.8 | 6.2 | 5.7 | 8.1 | 7.4 |
Dislocation by 3 stages | 0.3 | 0.3 | 1.9 | 1.1 | 2.1 | 2.7 | 0.6 | 1.6 |
Estimations of the stage-specific numbers of cases
Breast cancer | Malignant melanoma | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Observed | PR | PMM | RF | Prop | Observed | PR | PMM | RF | Prop | ||
T-stage | |||||||||||
1 | N | 8,909.0 | 8,903.2 | 8,903.5 | 8,788.2 | 8,950.5 | 1,017.0 | 1,009.8 | 1,014.5 | 962.3 | 1,013.7 |
SD
|
94.4
|
96.5
|
96.5
|
108.6
|
97.6
|
31.9
|
37.4
|
38.2
|
207.2
|
37.3
| |
2 | N | 6,235.0 | 6,236.7 | 6,239.5 | 6,394.9 | 6,228.6 | 338.0 | 341.8 | 340.2 | 332.7 | 341.2 |
SD
|
79.0
|
82.6
|
83.0
|
83.3
|
84.1
|
18.4
|
26.8
|
29.9
|
116.8
|
25.7
| |
3 | N | 944.0 | 944.5 | 946.7 | 944.9 | 936.4 | 214.0 | 212.1 | 209 | 242.1 | 209.0 |
SD
|
30.7
|
33.0
|
33.3
|
33.8
|
32.7
|
14.6
|
18.7
|
19.2
|
129.6
|
17.7
| |
4 | N | 1,074.0 | 1,077.6 | 1,072.3 | 1,034.1 | 1,046.5 | 116.0 | 121.3 | 121.3 | 147.9 | 121.1 |
SD
|
32.8
|
36.3
|
35.9
|
57.3
|
35.3
|
10.8
|
13.6
|
15.5
|
121.8
|
16.6
| |
MAD | 59.8 | 57.8 | 341.9 | 104.1 | 48.4 | 55.4 | 409.2 | 49.2 | |||
SD
|
23.3
|
30.1
|
97.5
|
30.4
|
23.5
|
26.1
|
242.6
|
20.3
| |||
UICC-stage | |||||||||||
I | N | 6,859.0 | 6,865.7 | 6,856.7 | 6,096.1 | 6,642 | 1,321.0 | 1,269.8 | 1,276.8 | 1,213.7 | 1,267.8 |
SD
|
82.8
|
85.4
|
85.4
|
261.0
|
85.5
|
36.3
|
39.5
|
41.1
|
222.0
|
41.7
| |
II | N | 7,123.0 | 7,119.5 | 7,133.9 | 6,891.8 | 7,295.9 | 216.0 | 204.4 | 208.4 | 271.1 | 238.6 |
SD
|
84.4
|
87.5
|
87.4
|
425.7
|
88.8
|
14.7
|
24.7
|
24.8
|
143.1
|
21.5
| |
III | N | 2,371.0 | 2,361.7 | 2,351.9 | 3,206.1 | 2,462.6 | 122.0 | 149.9 | 124.5 | 173.4 | 143.6 |
SD
|
48.7
|
53.2
|
53.0
|
381.6
|
58.4
|
11.0
|
21.2
|
22.9
|
199.8
|
17.5
| |
IV | N | 809.0 | 815.1 | 819.5 | 968.0 | 761.5 | 26.0 | 60.9 | 75.2 | 26.9 | 35.0 |
SD
|
28.4
|
31.3
|
31.6
|
593.6
|
32.2
|
5.1
|
14.8
|
18.4
|
8.6
|
9.5
| |
MAD | 68.5 | 72.7 | 2182.4 | 528.8 | 133.9 | 126.9 | 344.4 | 107.5 | |||
SD
|
25.8
|
30.9
|
988.5
|
47.2
|
28.1
|
35.6
|
411.8
|
41.5
|