Subgroup Analysis Using Multiple Linear Regression: Confounding, Interaction, Synergism

Abstract

When the size of the study permits, important demographic or baseline value-defined subgroups of patients can be studied for unusually large or small efficacy responses; e.g. comparison of effects by age, sex; by severity or prognostic groups. Naturally, such analyses are not intended to “salvage” an otherwise negative study, but may be may be helpful in refining patient or dose selection for subsequent studies.¹