RT Journal Article T1 Standardizing effect size from linear regression models with log-transformed variables for meta-analysis A1 Rodríguez-Barranco, Miguel A1 Tobías, Aurelio A1 Redondo, Daniel A1 Molina-Portillo, Elena A1 Sanchez-Perez, Maria-Jose K1 Meta-analysis K1 Systematic review K1 Log-transformation K1 Linear regression K1 Effect size K1 Regression coefficients K1 Metaanálisis K1 Revisión K1 Modelos lineales K1 Modelos estadísticos AB BackgroundMeta-analysis is very useful to summarize the effect of a treatment or a risk factor for a given disease. Often studies report results based on log-transformed variables in order to achieve the principal assumptions of a linear regression model. If this is the case for some, but not all studies, the effects need to be homogenized.MethodsWe derived a set of formulae to transform absolute changes into relative ones, and vice versa, to allow including all results in a meta-analysis. We applied our procedure to all possible combinations of log-transformed independent or dependent variables. We also evaluated it in a simulation based on two variables either normally or asymmetrically distributed.ResultsIn all the scenarios, and based on different change criteria, the effect size estimated by the derived set of formulae was equivalent to the real effect size. To avoid biased estimates of the effect, this procedure should be used with caution in the case of independent variables with asymmetric distributions that significantly differ from the normal distribution. We illustrate an application of this procedure by an application to a meta-analysis on the potential effects on neurodevelopment in children exposed to arsenic and manganese.ConclusionsThe procedure proposed has been shown to be valid and capable of expressing the effect size of a linear regression model based on different change criteria in the variables. Homogenizing the results from different studies beforehand allows them to be combined in a meta-analysis, independently of whether the transformations had been performed on the dependent and/or independent variables. PB Biomed Central YR 2017 FD 2017-03-17 LK http://hdl.handle.net/10668/2888 UL http://hdl.handle.net/10668/2888 LA en NO Rodríguez-Barranco M, Tobias A, Redondo D, Molina-Portillo E, Sánchez-Pérez MJ. Standardizing effect size from linear regression models with log-transformed variables for meta-analysis. BMC Med Res Methodol. 2017 Mar 17:17(1):44 DS RISalud RD Apr 17, 2025