title: Statistical issues in a metaregression analysis of randomized trials: impact on the dietary sodium intake and blood pressure relationship.
abstract: In a meta-analysis of randomized trials of the effects of dietary sodium interventions on blood pressure, we found substantial heterogeneity among the studies. We were interested in evaluating whether measurement error, known to be a problem for dietary sodium measures, publication bias, or confounding factors could be responsible for the heterogeneity. A measurement error correction was developed that corrects both the slope and the intercept and takes into account the sample size of each study and the number of measurements taken on an individual. The measurement error correction had a minimal effect on the estimates, although it performed well in simulated data. A smoothed scatter plot was used to assess publication bias. Metaregressions provide a convenient way to jointly assess the effects of several factors, but care must be taken to fit an appropriate model.
authors.affiliation: Division of Medical Genetics, Montreal General Hospital, Quebec, Canada. celia@ustat.utoronto.ca
authors.forename: C M
authors.initials: CM
authors.lastname: Greenwood
authors.forename: J P
authors.initials: JP
authors.lastname: Midgley
authors.forename: A G
authors.initials: AG
authors.lastname: Matthew
authors.forename: A G
authors.initials: AG
authors.lastname: Logan
mesh_terms: D015982:Bias; D001699:Biometry; D001794:Blood Pressure / Q000187:drug effects; D003627:Data Interpretation, Statistical; D006801:Humans; D006973:Hypertension / Q000178:diet therapy / Q000503:physiopathology; D015201:Meta-Analysis as Topic; D010349:Patient Compliance; D011643:Publishing; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012982:Sodium, Dietary / Q000008:administration & dosage
chemical_list: D012982:Sodium, Dietary