Hello, thank you all. I don't quite understand how to test different sensitivity analyzes with different correlation coefficients. What had occurred to me was to use the values ??after the intervention in the two groups and do a meta-regression using the baseline LDL level as a covariate, and thus adjust the result for it, but I don't know if that would be correct. In any case, I want to explain the case again, since out there it was interpreted as paired measurements and it is not. I have group A and Group B, in each group I have a baseline value of LDL and the value after the intervention, and I need to meta-analyze the impact on this variable. I usually do it already having the difference between baseline and post-treatment of the two groups with their deviations, but in this case I only have these data to make a difference of means. That's why I also asked how to do it with change scores, something like that had been explained to me by gerta but I didn't understand. Thanks a lot 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
De: Michael Dewey <lists at dewey.myzen.co.uk>
Enviado: lunes, 31 de enero de 2022 08:59 Para: Martin Lobo <mlobo4370 at hotmail.com>; Viechtbauer, Wolfgang (SP) <wolfgang.viechtbauer at maastrichtuniversity.nl>; r-sig-meta-analysis at r-project.org <r-sig-meta-analysis at r-project.org> Asunto: Re: [R-meta] Meta-analysis of mean differences Dear Martin I think the relevant part of the link to which Wolfgang directed you is "In practice, one is likely to encounter difficulties in actually obtaining those correlations from the information reported in the articles. In that case, one can substitute approximate values (e.g., based on known properties of the dependent variable being measured) and conduct a sensitivity analysis to ensure that the conclusions from the meta-analysis are unchanged when those correlations are varied." I suggest that you choose a range of plausible values for r and fit the model for each. If the scientific conclusion is unchanged over a range of values then you have your answer. If the exact value of r makes an important difference then you are a bit stuck unless you can persuade any of the authors to supply their r value. Michael On 30/01/2022 22:46, Martin Lobo wrote: > thanks wolfgang, the problem is that I don't get the correlation coefficients. Would it be valid to perform the meta-analysis with the post-treatment values ??and perform a meta-regression using the pre-treatment value as a covariate to assess whether the result is maintained regardless of the baseline value? > best reagards > > > > > 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 > > > ________________________________ > De: Viechtbauer, Wolfgang (SP) <wolfgang.viechtbauer at maastrichtuniversity.nl> > Enviado: domingo, 30 de enero de 2022 12:27 > Para: Martin Lobo <mlobo4370 at hotmail.com>; r-sig-meta-analysis at r-project.org <r-sig-meta-analysis at r-project.org> > Asunto: RE: [R-meta] Meta-analysis of mean differences > > Dear Lorenzo, > > This is relevant: > > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.metafor-project.org%2Fdoku.php%2Fanalyses%3Amorris2008&data=04%7C01%7C%7C917452bf7fa649f2762508d9e4b12212%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637792271704657168%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=mpX54JCpJmlPXjt1nA9ThhqAizRVr0Vb15QCoS5c1vI%3D&reserved=0 > > Best, > Wolfgang > >> -----Original Message----- >> From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On >> Behalf Of Martin Lobo >> Sent: Friday, 28 January, 2022 15:40 >> To: Dr. Gerta R?cker; r-sig-meta-analysis at r-project.org >> Subject: [R-meta] Meta-analysis of mean differences >> >> Hi all. How should I do a meta-analysis of mean differences having the initial >> and final values ??with their standard deviations for each group. With the metacont >> function I can only put mean 1, standard deviation 1 mean 1 and standard >> deviation 2 with their respective n. >> >> I think I should use a meta analysis of score changes but I don't know how to do >> it in R. >> >> regards >> >> 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 > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-meta-analysis mailing list > R-sig-meta-analysis at r-project.org > https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-meta-analysis&data=04%7C01%7C%7C917452bf7fa649f2762508d9e4b12212%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637792271704657168%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2B7ToiaeY1tbSCRdjj28GXAWEGXRbUYFN%2BCfU41Zw83E%3D&reserved=0 > > -- Michael https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.dewey.myzen.co.uk%2Fhome.html&data=04%7C01%7C%7C917452bf7fa649f2762508d9e4b12212%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637792271704657168%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=zkKdWDGjywPbH9fpWKAWg5%2Bvd4nWsAnDWUxdTGEW%2BIA%3D&reserved=0