Table 1. Prevalence and incidence of idiopathic pulmonary fibrosis (IPF) by geographic region

First author [ref.]	Country and study period	Study methods and case definition (year of estimate)	Age yrs	IPF prevalence per 100,000 population (95% CI)			Annual IPF incidence per 100,000 population (95% CI)
First author [ref.]	Country and study period	Study methods and case definition (year of estimate)	Age yrs	All	Male	Female	All	Male	Female
North America
Coultas [9]	USA, 1988–1990	Population-based ILD registry (1988–1990) Cases were identified using medical records, pathology reports, death certificates and autopsy reports	≥18		20.2	13.2		10.7	7.4
Fernández Pérez [11]	USA, 1997–2005	Olmsted County historical cohort (2005) Narrow case definition^#	≥50	27.9			8.8	13.38	6.08
				(10.4–45.4)			(5.28–12.38)	(6.51–20.24)	(2.08–10.08)
		Broad case definition^¶		63.0 (36.4–89.6)			17.43 (12.42–22.44)	24.02 (14.84–33.20)	13.43 (7.50–19.37)
Raghu [16]	USA, 1996–2000	Healthcare claims database (2000) Narrow case definition⁺	≥18	14.0			6.8
		Broad case definition^§		42.7			16.3
Europe
Thomeer [18]	Belgium, 1992–1996	Population-based ILD registry in 20 centres (1992–1996) Biopsy proven UIP were identified as IPF	All	1.25			0.22
Kolek [14]	Czech Republic, 1981–1990	Retrospective observational study in 24 centres (1990) Diagnosis based on histology or typical clinical symptoms, radiological pattern and functional changes	All	12.1			0.94
Hodgson [12]	Finland, 1997–1998	Pulmonary clinic databases nationwide (29 clinics) (1997–1998) IPF diagnosis according to ATS/ERS consensus (2000) [22]	All	16–18^ƒ
Karakatsani [13]	Greece, 2004	National survey of pulmonologists (2004) IPF diagnosis according to ATS/ERS consensus (2000) [22]	All	3.38			0.93
Von Plessen [20]	Norway, 1984–1998	Hospital records (1998) IPF cases identified based on physician diagnoses using ICD-8 (codes 517, 517.00, 517.01, 517.09) and ICD-9 (codes 515, 516.3, 516.8, and 516.9)	≥16	23.4^## (14.9–33.0)	16.8	30.7	4.3^##	4.0 (3.1–4.9)	4.6 (3.7–5.6)
Gribbin [7]	UK, 1991–2003	THIN database (1991–2003) IPF was diagnosed clinically or by open-lung biopsy	≥40				4.6 (4.3–4.9)	5.69 (5.24–6.18)	3.44 (3.10–3.82)
Navaratnam [8]	UK, 2000–2009	THIN database (2000–2009) IPF cases identified from primary care data and death records using ICD codes (ICD-8 code 517; ICD-9 codes 516.3 and 515; ICD-10 code J84.1)	≥40				7.44 (7.12–7.77)	9.46 (8.96–9.98)	5.46 (5.07–5.86)

ILD: interstitial lung disease; UIP: usual interstitial pneumonia; ATS: American Thoracic Society; ERS: European Respiratory Society; ICD: International Classification of Diseases; THIN: The Health Improvement Network. ^#: UIP on a surgical lung biopsy specimen or a definite UIP pattern on a high-resolution computed tomography (HRCT) image. ^¶: UIP on a surgical lung biopsy specimen, or a definite or possible UIP pattern on a HRCT image. ⁺: met broad case definition (see ^§) plus at least one medical claim with a procedure code for surgical lung biopsy, transbronchial lung biopsy or computed tomography of the thorax; on or before date of last medical claim with a diagnosis code for IPF. ^§: age ≥18 yrs, at least one medical claim with a diagnosis code for IPF (ICD-9-CM 516.3), no medical claims with a diagnosis code for any other ILDs on or after date of last medical claim with a diagnosis code for IPF. ^ƒ: IPF patients were estimated from evaluation, sampling and extrapolation methods combined. ^##: incidence and prevalence of hospitalised IPF.