[R-meta] meta-analysis of mean differences with only the difference and its SD

Martin Lobo m|obo4370 @end|ng |rom hotm@||@com
Tue Oct 5 16:00:41 CEST 2021 

Hi Gerta, I'm sorry, I was later.

I need to do a mean difference analysis. For example, there was a decrease in LDL with a drug versus a placebo. But I do not have the average value of each branch with its standard deviations. I have the difference of each branch with its confidence intervals. The metacont function asks me for n.e, mean value.e, SD.e, n.c, mean value.c, SD.c. Therefore, I do not know what function to use to analyze the difference between the two branches with their CIs or their deviations, having these data and the n of each branch. I do not know if I have been clear.
Thank you

PD
I have
n.e, ( mean.e - mean.c), IC ( mean.e - mean.c), n.c

I think there would be no problem in converting the IC to SD, so it would be like this

n.e, ( mean.e - mean.c), SD ( mean.e - mean.c), n.c




Lorenzo Martín Lobo MTSAC, FACC, FESC
Especialista Jerarquizado en Cardiología
Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital Militar Campo de Mayo.
Jefe de Cardiología Hospital Militar Campo de Mayo
Ex Jefe de Unidad Coronaria Hospital Militar Campo de Mayo
Miembro Titular de la Sociedad Argentina de Cardiología
Fellow American College of Cardiology
Fellow European Society of Cardiology
Ex Miembro del Area de Investigación de la SAC
Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC
Miembro Asesor del Consejo de Aterosclerosis y Trombosis de la SAC
Ex Director del Consejo de Epidemiología y Prevención Cardiovascular de la SAC

Miembro Asesor del Consejo de Epidemiología y Prevención Cardiovascular de la SAC


Experto en Lipidos de la Sociedad Argentina de Lipidos.
Miembro de la Sociedad Argentina de Lipidos.
Instructor de ACLS de la American Heart Association


________________________________
De: Dr. Gerta Rücker <ruecker using imbi.uni-freiburg.de>
Enviado: viernes, 17 de septiembre de 2021 09:44
Para: Martin Lobo <mlobo4370 using hotmail.com>; r-sig-meta-analysis using r-project.org <r-sig-meta-analysis using r-project.org>
Asunto: Re: [R-meta] meta-analysis of mean differences with only the difference and its SD


Dear Martin,

Again: Where is the problem? If you have the differences and their standard deviation from all studies, you can simply pool them in a meta-analysis of change scores. Or is the problem that you have differences for some studies and post values for others?

Probably this helps: https://training.cochrane.org/handbook/current/chapter-10#section-10-5-2<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftraining.cochrane.org%2Fhandbook%2Fcurrent%2Fchapter-10%23section-10-5-2&data=04%7C01%7C%7C05240848802d49dd05b508d979d8d6fb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637674794702961214%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=k2pBsOMbHyJKJQbbR%2F%2BcdDPIuEMcYeIpbILpnM2FOKU%3D&reserved=0>

Best,

Gerta

Am 17.09.2021 um 14:35 schrieb Martin Lobo:
Hi Gerta.  Thanks.  My question is how to perform the meta analysis having only the difference.  The ones that I have done put the pre and post values, in this I already have the difference.  it would be a single branch.

Than`s again

Lorenzo Martín Lobo MTSAC, FACC, FESC

________________________________
From: Dr. Gerta Rücker <ruecker using imbi.uni-freiburg.de><mailto:ruecker using imbi.uni-freiburg.de>
Sent: Thursday, September 16, 2021 2:33:48 PM
To: Martin Lobo <mlobo4370 using hotmail.com><mailto:mlobo4370 using hotmail.com>; r-sig-meta-analysis using r-project.org<mailto:r-sig-meta-analysis using r-project.org> <r-sig-meta-analysis using r-project.org><mailto:r-sig-meta-analysis using r-project.org>
Subject: Re: [R-meta] meta-analysis of mean differences with only the difference and its SD


Dear Martin,

I don't understand your problem.

- You write you want to do meta-analysis of differences of means. Do you mean pre-post differences? It is not clear.

- You further write you have the difference with its standard deviations, not the initial (pre) or the final (post) values. So, why do you ask how to calculate the difference if you already have it?

Please clarify.

Best,

Gerta

Am 15.09.2021 um 15:23 schrieb Martin Lobo:

Hello everyone,
 I need to do a meta-analysis of differences of means. I have the difference with its standard deviations, I do not have the initial or final values. What method should I use in this case to have only the value of the difference? The generic method of variance?
Thank you




Lorenzo Mart�n Lobo MTSAC, FACC, FESC
Especialista Jerarquizado en Cardiolog�a
Jefe de Dpto Enf. Cardiovasculares y Cardiometabolismo Hospital Militar Campo de Mayo.
Jefe de Cardiolog�a Hospital Militar Campo de Mayo
Ex Jefe de Unidad Coronaria Hospital Militar Campo de Mayo
Miembro Titular de la Sociedad Argentina de Cardiolog�a
Fellow American College of Cardiology
Fellow European Society of Cardiology
Ex Miembro del Area de Investigaci�n de la SAC
Ex Director del Consejo de Aterosclerosis y Trombosis de la SAC
Miembro Asesor del Consejo de Aterosclerosis y Trombosis de la SAC
Ex Director del Consejo de Epidemiolog�a y Prevenci�n Cardiovascular de la SAC

Miembro Asesor del Consejo de Epidemiolog�a y Prevenci�n Cardiovascular de la SAC


Experto en Lipidos de la Sociedad Argentina de Lipidos.
Miembro de la Sociedad Argentina de Lipidos.
Instructor de ACLS de la American Heart Association








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Dr. rer. nat. Gerta Rücker, Dipl.-Math.

Guest Scientist
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Zinkmattenstr. 6a, D-79108 Freiburg, Germany

Mail:     ruecker using imbi.uni-freiburg.de<mailto:ruecker using imbi.uni-freiburg.de>
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--

Dr. rer. nat. Gerta Rücker, Dipl.-Math.

Guest Scientist
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Zinkmattenstr. 6a, D-79108 Freiburg, Germany

Mail:     ruecker using imbi.uni-freiburg.de<mailto:ruecker using imbi.uni-freiburg.de>
Homepage: https://www.uniklinik-freiburg.de/imbi-en/employees.html?imbiuser=ruecker<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.uniklinik-freiburg.de%2Fimbi-en%2Femployees.html%3Fimbiuser%3Druecker&data=04%7C01%7C%7C05240848802d49dd05b508d979d8d6fb%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637674794702981208%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=VoDSfCkqy5O5zp4tT%2Bi%2BAmSnFb1aHGdxJbDkY%2F5yeHY%3D&reserved=0>

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