Table 1

Studies reporting IPF prevalence per 100 000 persons by various case definitions

Case definitions	Prevalence estimate (per 100 000 persons)	Case descriptions	Country, author-published year
General/primary	36	Patients with at least 1 hospitalisation or at least 1 outpatient visits with IPF diagnosis	Italy, Harari,13 2016
General/primary	13	Patients with at least 1 claim with IPF diagnosis.	USA, Raghu,2 2016
Overall IPF	20	Patients with at least 1 IPF inpatient claim, or 2 IPF outpatient claims with ICD code with no other ILD claim	USA, Raimundo,14 2016
Overall IPF	35	IPF diagnostic K codes	South Korea, Lee,15 2016
Broad	1160	Patients who had a code for IPF with no other ILD	USA, Zhang,16 2021
Broad	11	Patients with code of ICD 516.3, patients excluded if they had a claim with code 515 after the last ICD code 516.3	USA, Raghu,2 2016
Broad	42	Patients with code ICD code J84.1, cases with diagnosis of another ILD excluded	Canada, Hopkins,17 2016
Broad	22	Patients with IPF code and no claims for other ILD diagnosis	Italy, Harari,13 2016
Broad	39	Patients with Read codes: H563.00, H563.12, H563300, H563.13, H563100, H563200 and H563.11	UK, Strongman,18 2018
Narrow	13	Patients that satisfied the broad definition Had 1> claim with procedure code for SLB, TLB or CT thorax	Italy, Harari,13 2016
Narrow	725	Patients who had a code for IPF And if they did not have any other code for an alternative ILD And patients who had procedure code for an SLB or a thorax	USA, Zhang,16 2021
Narrow	7	Patients with an ICD code of 516.3 and they were excluded if they had a claim with the ICD code 515 And further restricted by requiring a claim for an SLB, TLB or CT thorax	USA, Raghu,2 2016
Narrow	20	Patients with ICD codes J84.1 with no other ILD and excluded cases that did not have chest CT, bronchus or SLB or bronchoscopy	Canada, Hopkins,17 2016

ICD, International Classification of Diseases; ILD, interstitial lung disease; IPF, Idiopathic pulmonary fibrosis; SLB, surgical lung biopsy; TLB, transbronchial lung biopsy.