Re: [R] Meta-Analysis of proportions

From: Chuck Cleland <ccleland_at_optonline.net>
Date: Thu, 28 Jun 2007 07:51:49 -0400

Monica Malta wrote:
> Dear colleagues,
>
> I'm conducting a meta-analysis of studies evaluating adherence of HIV-positive drug users into AIDS treatment, therefore I'm looking for some advice and syntax suggestion for running the meta-regression using proportions, not the usual OR/RR frequently used on RCT studies.
>
> Have already searched already several handbooks, R-manuals, mailing lists, professors, but... not clue at all...
>
> Does anyone have already tried this? A colleague of mine recently published a similar study on JAMA, but he used OpenBUGS - a software I'm not familiar with...
>
> If there is any tip/suggestion for a possible syntax, could someone send me? I need to finish this paper before my PhD qualify, but I'm completely stuck...
>
> So, any tip will be more than welcome...I will really appreciate it!!!
>
> Thanks in advance and congrats on the amazing mailing-list.

  Specifying adherence as the "effect size", if you can also specify a sampling variance perhaps you can use a tool like mima (http://www.wvbauer.com/downloads/mima_tutorial.pdf). For example, working with logits rather than proportions directly, consider the following example data:

> df

   ntot nadhere mod      prop      logit        se
1   100      76   0 0.7600000 -1.1526795 0.2341463
2   125      98   0 0.7840000 -1.2891306 0.2173501
3    50      37   0 0.7400000 -1.0459686 0.3224127
4   200     159   0 0.7950000 -1.3553321 0.1751557
5   150     114   0 0.7600000 -1.1526795 0.1911796
6    80      56   1 0.7000000 -0.8472979 0.2439749
7   160     113   1 0.7062500 -0.8772402 0.1735688
8   200     130   1 0.6500000 -0.6190392 0.1482498
9   120      75   1 0.6250000 -0.5108256 0.1885618
10  105      78   1 0.7428571 -1.0608720 0.2232879

  Then do the meta-regression as follows:

> source("http://www.wvbauer.com/downloads/mima.ssc")

> with(df, mima(yi=logit, vi=se, mods=mod))

Estimate of (Residual) Heterogeneity: 0

Test for (Residual) Heterogeneity:

QE      =  1.2419
df      =  8
p-value =  0.9962

Parameter Estimates:

           [,1]
intrcpt -1.2161
mods 0.4520

Variance-Covariance Matrix of Parameter Estimates:

        intrcpt mods
intrcpt 0.0436 -0.0436
mods -0.0436 0.0815

Omnibus Test of all Moderators:

QME     =  2.5058
df      =  1
p-value =  0.1134

Individual Moderator Tests:

        estimate SE zval pval CI_L CI_U intrcpt -1.2161 0.2089 -5.8213 0.0000 -1.6256 -0.8067 mods 0.4520 0.2856 1.5830 0.1134 -0.1077 1.0117

> Bests from Rio de Janeiro, Brazil.
>
> Monica
>
> Monica Malta
> Researcher
> Oswaldo Cruz Foundation - FIOCRUZ
> Social Science Department - DCS/ENSP
> Rua Leopoldo Bulhoes, 1480 - room 905
> Manguinhos
> Rio de Janeiro - RJ 21041-210
> Brazil
> phone +55.21.2598-2715
> fax +55.21.2598-2779
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>
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-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
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New York, NY 10010
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Received on Thu 28 Jun 2007 - 13:03:45 GMT

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