TABLE 1

Study characteristics

Characteristic
Continent
 North America50 (40)
 Asia36 (29)
 Europe36 (29)
 South America2 (2)
 Africa1 (1)
 Oceania1 (1)
 Total126 (100)+
Study type
 Retrospective cohort study85 (67)
 Prospective cohort study25 (20)
 Case−control study10 (8)
 Cross-sectional study5 (4)
 Case series1 (1)
 Mean (median, range) number of IPF patients270 (70, 8–9286)
 Mean# age of IPF patients years65.3
Comorbidities
Respiratory
 Pulmonary hypertension43 (34)
 Chronic obstructive pulmonary disease/emphysema23 (18)
 Lung cancer15 (12)
 Obstructive sleep apnoea7 (6)
 Pulmonary embolism3 (2)
Nonrespiratory
 Cardiovascular34 (27)
 Metabolic30 (24)
 Gastro-oesophageal reflux disease23 (18)
  • Data are presented as n (%), unless otherwise stated. IPF: idiopathic pulmonary fibrosis. #: value is mean of the mean age reported in the studies (n=92 studies); : papers could have reported more than one comorbidity; +: may not total 100% due to rounding.