The current evidence does not demonstrate conclusively that NSB consumption has uniquely contributed to obesity or that reducing NSB consumption will reduce BMI levels in general .
Nutritively sweetened beverages ( NSBs ) may play a role in the obesity epidemic .
Subgroup analysis and other (mis)uses of baseline data in clinical trials
BACKGROUND Baseline data collected on each patient at r and omisation in controlled clinical trials can be used to describe the population of patients , to assess comparability of treatment groups , to achieve balanced r and omisation , to adjust treatment comparisons for prognostic factors , and to undertake subgroup analyses . We assessed the extent and quality of such practice s in major clinical trial reports . METHODS A sample of 50 consecutive clinical -trial reports was obtained from four major medical journals during July to September , 1997 . We tabulated the detailed information on uses of baseline data by use of a st and ard form . FINDINGS Most trials presented baseline comparability in a table . These tables were often unduly large , and about half the trials inappropriately used significance tests for baseline comparison . Methods of r and omisation , including possible stratification , were often poorly described . There was little consistency over whether to use covariate adjustment and the criteria for selecting baseline factors for which to adjust were often unclear . Most trials emphasised the simple unadjusted results and covariate adjustment usually made negligible difference . Two-thirds of the reports presented subgroup findings , but mostly without appropriate statistical tests for interaction . Many reports put too much emphasis on subgroup analyses that commonly lacked statistical power . INTERPRETATION Clinical trials need a predefined statistical analysis plan for uses of baseline data , especially covariate-adjusted analyses and subgroup analyses . Investigators and journals need to adopt improved st and ards of statistical reporting , and exercise caution when drawing conclusions from subgroup findings
The current evidence does not demonstrate conclusively that NSB consumption has uniquely contributed to obesity or that reducing NSB consumption will reduce BMI levels in general .
Nutritively sweetened beverages ( NSBs ) may play a role in the obesity epidemic .