TABLE 1

Characteristics of studies identified

CharacteristicsDetails
Study type
  • 154 cohort studies (64% retrospective design)#

  • 16 RCTs

Publication year
  • Before 1990: n=6

  • 1990–1999: n=17

  • 2000–2009: n=38

  • Since 2010: n=109

Location
  • Europe: n=60

  • Asia: n=47

  • American continent: n=45

  • Australia: n=5

IPF diagnostic criteria
  • 2011 ATS/ERS/JRS/ALAT guideline: n=41

  • 2000 ATS/ERS international consensus statement: n=57

  • Other: n=72

DesignCohort study#
  • Prospective design (n=55): 73% single-centre, 20% multicentre, 5% registry/database, 2% unclear

  • Retrospective design (n=98): 79% single-centre, 12% multicentre, 8% registry/database, 1% unclear

RCT (n=16): all multicentre trials
Participant numberCohort study#
  • Prospective design (n=55): median (range) 44 (7–588)

  • Retrospective design (n=98): median (range) 81 (11–13 615)

RCT (n=16): median (range) 94 (28–423)
DurationCohort study#,+
  • Prospective design (n=55): 40% between 1 year and <2 years; 33% between 2–5 years; 13% ≥5 years

  • Retrospective design (n=98): 43% between 1 year and <2 years; 12% between 2–5 years; 10% ≥5 years

RCT (n=16): all with a study duration of 1 year and <2 years

IPF: idiopathic pulmonary fibrosis; ATS: American Thoracic Society; ERS: European Respiratory Society; JRS: Japanese Respiratory Society; ALAT: Latin American Thoracic Association; RCT: randomised controlled trial. #: not including Mura et al. [110]: a single-centre study with both prospective (n=70) and retrospective (n=68) cohorts, with a study duration ≥3 years; : number of participants in the placebo arm only; +:: all studies had a study duration ≥1 year. Some studies provided mean or median follow-up duration which could not be incorporated into the table.