Meta-analysis using individual participant data: one-stage and two-stage approaches, and why they may differ

Meta-analysis using individual participant data (IPD) obtains and synthesises the raw, participant-level data from a set of relevant studies. The IPD approach is becoming an increasingly popular tool as an alternative to traditional aggregate data meta-analysis, especially as it avoids reliance on published results and provides an opportunity to investigate individual-level interactions, such as treatment-effect modifiers. There are two statistical approaches for conducting an IPD meta-analysis: one-stage and two-stage. The one-stage approach analyses the IPD from all studies simultaneously, for example, in a hierarchical regression model with random effects. The two-stage approach derives aggregate data (such…

• NI
  National Institute for Health and Care Research
• MR
  Medical Research Council

  Awards: MR/J013595/2, MR/J013595/1, MR/J013595/1
• NS
  NIHR School for Primary Care Research