Intercurrent Events

The background

Intercurrent event: event occurring after initiation of study intervention which either precludes the observation of the outcome variable or affects its measurement or interpretation.

The data

• 800 subjects randomised 1:1 to Treatment A or Treatment B
• Patients respond to a visual analogue scale (0=worst outcome, 100=best outcome) monthly for one year
• Variables: (1) USUBJID (2) TRT (3) AVISIT (4) AVAL (5) ICE
  • ICE is an indicator variable (Y or N), reflecting whether the visit is preceeded by an intercurrent event

The data can be found here.

The challenge

Compare the two treatment arms, considering how intercurrent events might be handled.

Considerations

• Possible outcomes:
  • Mean score / mean change / mean % change
  • % of patients achieving a score >=X
• How to handle intercurrent events?
  • Ignore
  • Set to missing and impute
  • Impute as non-response
  • Something else?