Evidence synthesis — meta-analysis forest and funnel plots

// Random-effects meta-analysis of twelve randomised trials drawn twice from one set of study rows: a forest plot with subgroups, pooled diamonds and the prediction interval, and a funnel plot with Egger's test and trim-and-fill.
//
// Every string below is EXAMPLE text from a fictional review: replace it.
//
// Each study is a contrast row carrying its own 2×2 table: events_a / n_a
// in the exercise-based cardiac rehabilitation arm, events_b / n_b under
// usual care, for all-cause hospital admission at 12 months. The risk
// ratio and its interval for every row, the inverse-variance weights,
// tau², I², Q, the subgroup diamonds, the test for subgroup differences,
// the prediction interval, Egger's regression and the funnel's pseudo-
// confidence contours are all computed from those counts. Change one
// count and both figures, and every statistic on them, move together;
// there is no pooled number typed anywhere in this document.
//
// Pooling: random effects, DerSimonian–Laird tau² with the
// Hartung–Knapp–Sidik–Jonkman interval, which Cochrane recommends when
// the number of studies is small. Subgroups (centre-based versus
// home-based programmes) were specified in the protocol before any data
// were extracted.

meta rehab_admission {
  title: "Cardiac rehabilitation versus usual care: admission at 12 months"
  measure: rr
  scale: log
  model: hksj
  level: 0.95
  k: 12
  n: 2406
  subgroup centre_based {
    variable: "Programme setting"
    category: "Centre-based"
    prespecified: true
    contrast okafor {
      label: "Okafor 2012"
      events_a: 12
      n_a: 60
      events_b: 25
      n_b: 60
    }
    contrast lindqvist {
      label: "Lindqvist 2013"
      events_a: 37
      n_a: 155
      events_b: 53
      n_b: 155
    }
    contrast moreau {
      label: "Moreau 2015"
      events_a: 58
      n_a: 210
      events_b: 80
      n_b: 210
    }
    contrast silva {
      label: "Silva 2017"
      events_a: 6
      n_a: 32
      events_b: 13
      n_b: 32
    }
    contrast abdi {
      label: "Abdi 2019"
      events_a: 29
      n_a: 91
      events_b: 21
      n_b: 91
    }
    contrast haddad {
      label: "Haddad 2021"
      events_a: 45
      n_a: 270
      events_b: 69
      n_b: 270
    }
    contrast ito {
      label: "Ito 2023"
      events_a: 9
      n_a: 38
      events_b: 8
      n_b: 38
    }
  }
  subgroup home_based {
    variable: "Programme setting"
    category: "Home-based"
    prespecified: true
    contrast hartmann {
      label: "Hartmann 2014"
      events_a: 10
      n_a: 48
      events_b: 13
      n_b: 48
    }
    contrast tanaka {
      label: "Tanaka 2016"
      events_a: 26
      n_a: 75
      events_b: 28
      n_b: 75
    }
    contrast novak {
      label: "Novak 2018"
      events_a: 28
      n_a: 114
      events_b: 35
      n_b: 114
    }
    contrast kowalczyk {
      label: "Kowalczyk 2020"
      events_a: 11
      n_a: 44
      events_b: 8
      n_b: 44
    }
    contrast brennan {
      label: "Brennan 2022"
      events_a: 20
      n_a: 66
      events_b: 31
      n_b: 66
    }
  }
}

view forest_plot: forest(rehab_admission)
view small_study_effects: funnel_plot(rehab_admission)