[R-meta] Fwd: meta analysis package "metafor" --- one group survival outcome?

Viechtbauer Wolfgang (SP) wolfgang.viechtbauer at maastrichtuniversity.nl
Wed Jun 28 16:57:32 CEST 2017

A method for pooling KM estimates (at a particular time point) across multiple studies is described in:

Coplen, S. E., Antman, E. M., Berlin, J. A., Hewitt, P., & Chalmers, T. C. (1990). Efficacy and safety of quinidine therapy for maintenance of sinus rhythm after cardioversion: A meta-analysis of randomized control trials. Circulation, 82(4), 1106-1116.

In essence, we can just pool the KM estimates in the usual manner (FE/RE model). The variance of the KM estimates can be computed using Greenwood's formula (https://en.wikipedia.org/wiki/Kaplan%E2%80%93Meier_estimator#Statistical_considerations).

You can do the pooling with metafor (or other packages). In metafor, just use rma(yi, vi) where yi are the KM estimates and vi the corresponding variances.

This approach uses the KM estimates directly. Indeed, the sampling distribution of KM estimates may not be normal, but that may not be a major issue unless you suspect that the underlying true survival rates are close to 0 or 1.

As for your question about a sample size calculation -- I am not quite sure what you are after. You (typically) do not have any influence on the number of studies included in a meta-analysis or the sample sizes thereof. So what are you trying to accomplish here?


>-----Original Message-----
>From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-
>project.org] On Behalf Of Hong Zhao
>Sent: Wednesday, June 28, 2017 04:26
>To: r-sig-meta-analysis at r-project.org
>Subject: [R-meta] Fwd: meta analysis package "metafor" --- one group
>survival outcome?
>Dear all,
>I have a question for R package "metafor". On page 35 of the package file,
>I saw the meta-analysis for a two sample survival analysis, does anyone
>know whether I can use this package to do one-sample survival analysis?
>Here is what I have: three 3 studies with all the survival information
>(time to event and censor information). I want to combine the survival
>rates (KM estimates) at 6 months for these 3 studies using meta-analysis.
>Since the survival rates are not normally distributed and I cannot just
>simply treat them as proportions to use meta-analysis method for normal
>data or proportion data, I am not sure whether I can just transform them
>using log(survival rate) (and get their variance accordingly) and use
>meta-analysis for normal data. Does anyone know a better way to do it? Or
>can the package perform the meta-analysis for a single group survival
>BTW, does anyone know any method for sample size calculation for
>meta-analysis (outcome is one-sample binomial or survival outcome as I
>mentioned above)? I want to perform non-inferiority test, but did not find
>anything available from online for meta-analysis sample size
>calculation for either binomial or survival outcome. I guess I may need to
>just do simulation if there is no available sources.
>Thanks so much for your kind help!

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