[R-meta] converting Odds Ratio to Risk Ratio in CHE model

Thu, Apr 18, 2024 4:24 AM

I totally understand that part, but I am not quite sure which OR values you want to convert. If you fitted a model to standardized mean differences, then one cannot really transform the estimates from such a model to risk ratios (well, maybe, with a lot of creativity, but let's not go there). If you are simply asking how to convert ORs to RRs, then this can be done, but requires assuming a baseline risk. The transf.lnortorr() function in metafor will do this (to be precise, it transforms log odds ratios to risk ratios). For example, say the OR is 2.5. Then the corresponding RR is:

transf.lnortorr(log(2.5), pc=0.10)

2.17, assuming that the baseline risk is 10%. But if the baseline risk is 20%, then

transf.lnortorr(log(2.5), pc=0.20)

shows that the corresponding RR is 1.92.

Best,
Wolfgang

-----Original Message-----
From: Sicong Liu <64zone at gmail.com>
Sent: Thursday, April 18, 2024 13:04
To: Viechtbauer, Wolfgang (NP) <wolfgang.viechtbauer at maastrichtuniversity.nl>; R
Special Interest Group for Meta-Analysis <r-sig-meta-analysis at r-project.org>
Subject: Re: converting Odds Ratio to Risk Ratio in CHE model

Thank you for your response Wolfgang!

I apologize for not being clear and the question is totally motivated by making
the interpreation easier. The targeted audience of the work is in public health.
Although OR is  used in this domain,  some people find it difficult to think in
terms of "odds", which is not as easy as "chance"  interpreted from RR, hence
the question. Thank you!

Cheers,
Sicong (Zone)
-------------

From: Viechtbauer, Wolfgang (NP) <wolfgang.viechtbauer at maastrichtuniversity.nl>
Date: Thursday, April 18, 2024 at 6:16 PM
To: R Special Interest Group for Meta-Analysis <r-sig-meta-analysis at r-
project.org>
Cc: Liu Sicong <64zone at gmail.com>
Subject: RE: converting Odds Ratio to Risk Ratio in CHE model
Dear Sicong,

I don't understand the question (seems to be pattern for me today ...). If you
converted everything to SMDs, then the results from the model provides estimates
in terms of this (SMD) measure. So where / why do you want to convert ORs to
RRs?

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis <r-sig-meta-analysis-bounces at r-project.org> On

Behalf

Of Liu Sicong via R-sig-meta-analysis
Sent: Wednesday, April 17, 2024 10:07
To: r-sig-meta-analysis at r-project.org
Cc: Liu Sicong <64zone at gmail.com>
Subject: [R-meta] converting Odds Ratio to Risk Ratio in CHE model

Dear All,

Hope all is well.

I have been applying the correlated and hierarchical model (CHE, Pustejovsky &
Tipton, 2021) to fitting data consisting of ~98 clinical trials with binary
outcomes. The effect sizes took the initial form of odds ratio (OR) and were
converted to the standard mean difference (SMD) when fitting the CHE model.
Because OR is challenging for interpretation and I wonder if there are ways to
transform from OR to risk ratio (RR) when reporting the model parameter
estimates? Or, as some literature (see Knol et al., 2012) suggests, converting
to RR entails a change of model?

Thank you all very much!

Pustejovsky, J. E., & Tipton, E. (2022). Meta-analysis with robust variance
estimation: Expanding the range of working models. Prevention Science, 23(3),
425-438.

Knol, M. J., Le Cessie, S., Algra, A., Vandenbroucke, J. P., & Groenwold, R.

H.

(2012). Overestimation of risk ratios by odds ratios in trials and cohort
studies: alternatives to logistic regression. Cmaj, 184(8), 895-899.

Best regards,
Sicong

------------------------------------------
Sicong (Zone) Liu, Ph.D.
Professor
South China Normal University
------------------------------------------

[R-meta] converting Odds Ratio to Risk Ratio in CHE model

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