Background
Methods
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b the number of resampling steps.
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ncontrol the number of control patients in already recruited study arm.
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ntreated,interim the number of treated patients at interim analysis.Step 1Repeat (a) - (d) b times:(a)Sample ntreated,interim patients without replacement out of the control group.(b)Calculate propensity scores for sampled control patients and treated patients.(c)Conduct a 1:1 matching according to the logit of the propensity scores.(d)Calculate the matching rate mr.Step 2Calculate the mean matching rate \(\overline {mr}\) of the b matching rates calculated in step 1.
Simulation setting
General setting
Variable | Group | Distribution | Model |
---|---|---|---|
X
1
| both | Bin(1;0.5) | |
X
2
| both | Bin(1;0.2) | |
X
3
| both | N(70;15) | |
Z
|
\(logit\left (\frac {P(Z=1)}{1-P(Z=1)}\right)\)
| ||
=−0.6+0.35X1−0.01X3 | |||
X
4
| control | Bin(10;0.8) | |
X
4
| treated | Bin(10;0.75) | |
X
5
| control | N(17;5) | |
X
5
| treated | N(16;4) | |
\(Y_{H_{0}}\)
| both | Bin(1;0.5) | |
\(Y_{H_{1}}\)
| both |
\(logit\left (\frac {P(Y=1)}{1-P(Y=1)}\right)\)
| |
=−0.5+Z+0.2X4 |
Fixed time point - varying number of control patients
Time point of interim analysis
Results
Simulation results
Fixed time point - varying number of control patients
Interim | Final | Interim | Final | |
---|---|---|---|---|
n
control
| Naiv | 99%-CI | ||
50 | 0.89 | 0.79 | 0.49 | 0.92 |
75 | 0.93 | 0.81 | 0.58 | 0.92 |
100 | 0.95 | 0.82 | 0.64 | 0.92 |
125 | 0.96 | 0.83 | 0.67 | 0.92 |
150 | 0.97 | 0.84 | 0.70 | 0.92 |
175 | 0.98 | 0.84 | 0.72 | 0.92 |
200 | 0.98 | 0.84 | 0.73 | 0.92 |
225 | 0.98 | 0.85 | 0.74 | 0.92 |
250 | 0.99 | 0.85 | 0.76 | 0.92 |
275 | 0.99 | 0.85 | 0.76 | 0.92 |
300 | 0.99 | 0.86 | 0.77 | 0.92 |
95%-CI | 90%-CI | |||
50 | 0.54 | 0.91 | 0.56 | 0.90 |
75 | 0.62 | 0.91 | 0.64 | 0.90 |
100 | 0.67 | 0.91 | 0.68 | 0.91 |
125 | 0.70 | 0.91 | 0.71 | 0.91 |
150 | 0.72 | 0.91 | 0.73 | 0.91 |
175 | 0.74 | 0.91 | 0.75 | 0.91 |
200 | 0.75 | 0.91 | 0.76 | 0.91 |
225 | 0.76 | 0.91 | 0.77 | 0.91 |
250 | 0.77 | 0.91 | 0.78 | 0.91 |
275 | 0.78 | 0.91 | 0.79 | 0.91 |
300 | 0.79 | 0.91 | 0.80 | 0.91 |
n
control
| Naiv | 99%-CI | 95%-CI | 90%-CI |
---|---|---|---|---|
50 | 57.20 | 103.05 | 94.11 | 89.97 |
75 | 81.88 | 130.51 | 122.83 | 119.10 |
100 | 106.24 | 158.13 | 150.99 | 147.45 |
125 | 130.73 | 187.46 | 180.42 | 176.88 |
150 | 155.34 | 215.80 | 208.85 | 205.32 |
175 | 179.98 | 245.10 | 238.09 | 234.52 |
200 | 204.84 | 273.86 | 266.81 | 263.19 |
225 | 229.42 | 303.28 | 296.11 | 292.42 |
250 | 254.39 | 331.75 | 324.53 | 320.80 |
275 | 279.19 | 361.06 | 353.69 | 349.90 |
300 | 304.00 | 389.50 | 382.07 | 378.21 |