Table 1

Treatment effect modifiers examined in this IPD-MA

Treatment effect modifier
Participant’s demographic characteristicsAge at entry to trial
Participant’s clinical characteristicsEffect of specific diagnostic subgroups
Phase of illness (first-episode psychosis/multiple-episode psychosis)
Illness duration
Duration of untreated psychosis
Initial severity of psychotic symptoms (measured by baseline PANSS scores)
Initial severity of comorbid affective symptoms (measured by baseline anxiety scores)
Initial severity of comorbid affective symptoms (measured by baseline depression scores)
Dosage equivalence of baseline antipsychotic medication(s)27
Number of antipsychotic medications received at baseline
Specific intervention characteristicsTime period over which treatment was delivered*
Number of therapy sessions offered in the study*
Number of therapy sessions attended by the individual
Minimum study required level of therapist’s training and competence*
Measures of therapeutic alliance
Use of manualised interventions*
Use of formulation-based interventions*
Indicator for whether the intervention was designed to target the outcome under scrutiny*
Individual versus group interventions*
Length of study follow-up
  • *Treatment effect modifiers which are study-level variables, the remaining are individual-level variables.

  • IPD-MA, individual participant data meta-analysis; PANSS, Positive and Negative Syndrome Scale.