Table 2

Published estimates of IPF incidence, stratified by various case definitions

Incidence estimateCase definitionsCase descriptionsCountry,
author, published year
183.3 per 100 000 personsNRSelf-reportedUK, Belbasis, 202177
5.8 per 100 000 pyPrimaryPatients with at least one claim for idiopathic fibrosing alveolitisUSA, Raghu, 20162
5.2 (5.1–5.4) per 100 000 personsGeneralPatients with at least one hospitalisation or at least one outpatient visits with IPF diagnosisItaly, Harari, 201613
12.9 per 100 000 personsOverallDiagnostic codesSouth Korea, Lee, 201615
35.8 per 100 000 personsOverallDiagnostic codesSouth Korea, Lim, 201978
3.6–5.1 per 100 000 pyBroadPrimary patients with an exclusion of ICD code 515 after the last diagnosis code 516.3.USA, Raghu, 20162
18.7 per 100 000 personsBroadPatients with IPF diagnosis excluding cases with a diagnosis for another ILDCanada, Hopkins, 201617
331 per 100 000 pyBroadPatients who had a diagnosis code for IPFUSA, Zhang, 202116
3.7 (3.6–3.9) per 100 000 personsBroadPatients that satisfied the general definition and had no claims with another ILDItaly, Harari, 201613
8.7 (8.4–8.9) per 100 000 pyBroadIncluded Read codes

  • Idiopathic fibrosing alveolitis

  • Cryptogenic fibrosing alveolitis

  • Idiopathic fibrosing alveolitis NOS

  • Usual interstitial pneumonia (UIP)

  • IPF

UK, Strongman, 201818
2.4–2.9 per 100 000 pyNarrowBroad cases further restricted by requiring a claim for a surgical lung biopsy, TLB or CT thorax scanUSA, Raghu, 20162
9 per 100 000 personsNarrowPatients with IPF diagnosis excluding cases that did not have chest CT, bronchus or lung biopsy, or bronchoscopy recordCanada, Hopkins, 201617
2.3 (2.2–2.5) per 100 000 personsNarrow

  • Patients that satisfied the broad definition

  • Patients with a claim for SLB, TLB or CT thorax

Italy, Harari, 201613
2.8 (2.7–3) per 100 000 pyNarrowAdditional Read codes to the broad definitionUK, Strongman, 201818
210 per 100 000 pyNarrow

  • Patients who had a diagnosis code for IPF

  • And no other ILD diagnosis

  • Patients with SLB or a CT thorax before the last IPF diagnosis

USA, Zhang, 202116
48.5 per 100 000 personsDefinition 1ICD codes; (bronchoalveolar lavage, BAL) or lung biopsySouth Korea, Gjonbrataj, 201579
32.2 per 100 000 personsDefinition 2Diagnostic ICD code and HRCT, bronchoalveolar lavage or SLBSouth Korea, Gjonbrataj, 201579
16.2 per 100 000 personsDefinition 3ICD codeSouth Korea, Gjonbrataj, 201579
11.4 per 100 000 personsDefinition 4ICD code and HRCT, BAL or SLB; andSouth Korea, Gjonbrataj, 201579
11.4 per 100 000 personsDefinition 5ICD code based on the 2011 international statement.South Korea, Gjonbrataj, 201579

  • Details on the study population, sample size and ILD diagnosis methods are summarised in online supplemental tables E1–E31.

  • HRCT, high-resolution CT; ICD, International Classification of Disease; ILD, interstitial lung disease; IPF, idiopathic pulmonary fibrosis; NOS, Newcastle Ottawa scale; NR, not reported; py, person-years; SLB, surgical lung biopsy; TLB, transbronchial lung biopsy.