Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
Surrogacy Case Study: Prostate Specific Antigen (PSA ... - Isped
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Meta-analytic validation<br />
First stage: a joint model for<br />
individual observations on surrogate<br />
and true endpoints (Tij,Sij)<br />
Second stage: a linear model for the<br />
trial-specific trt effects ⎛αi<br />
⎞ ⎛α<br />
⎞ ⎛a<br />
i<br />
⎜<br />
⎟ = ⎜ ⎟ +<br />
⎜<br />
⎝ βi<br />
⎠ ⎝ β ⎠ ⎝b<br />
i<br />
⎟ ⎞<br />
⎠<br />
Trial-unit 1<br />
Trial-unit 2<br />
Trial-unit 3<br />
Trial-unit 4<br />
.<br />
.<br />
Trial-unit k<br />
(α <strong>PSA</strong><br />
, β OS<br />
)<br />
(α <strong>PSA</strong><br />
, β OS<br />
)<br />
(α <strong>PSA</strong><br />
, β OS<br />
)<br />
(α <strong>PSA</strong><br />
, β OS<br />
)<br />
.<br />
.<br />
(α <strong>PSA</strong><br />
, β OS<br />
)<br />
β OS<br />
R 2 trial<br />
close to 1<br />
Slope = R² trial<br />
α <strong>PSA</strong><br />
To allow precise prediction of the survival<br />
treatment effect from the <strong>PSA</strong> treatment<br />
effect<br />
Ref: Buyse et al, Biostatistics 2000; Burzykowski et al, Applied Statistics 2001
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