Incidence and Prevalence

Latest Estimates of Incidence and Prevalence of Idiopathic Pulmonary Fibrosis Globally

Global Trends

The incidence of IPF is increasing worldwide as populations age. For studies from 2000 onwards, a conservative incidence range of 3-9 cases per 100,000 per year was estimated for Europe and North America, with lower incidence reported in East Asia and South America. Most studies show an increase in incidence over time, with rates converging across countries.

A 2021 study estimated the adjusted global prevalence of IPF to be in the range of 0.33-4.51 per 10,000 persons. The most recent data (2024) indicates that interstitial lung disease (ILD) has an incidence ranging from 1 to 31.5 per 100,000 person-years and prevalence from 6.3 to 71 per 100,000 people.

Regional Estimates

North America

In the United States, IPF prevalence estimates varied between 14 and 27.9 cases per 100,000 population using narrow case definitions and 42.7 to 63 per 100,000 using broad definitions. A 2020 study reported IPF prevalence at 58.7 per 100,000 persons. The annual incidence was estimated at 6.8-8.8 per 100,000 (narrow definition) and 16.3-17.4 per 100,000 (broad definition).

In Canada, incidence rates were 18.7 per 100,000 (broad definition) and 9.0 per 100,000 (narrow definition). In Quebec, incidences were 25.8 and 21.7 per 100,000 for broad and narrow definitions, respectively.

Europe

In Europe, IPF prevalence ranged from 1.25 to 23.4 cases per 100,000 population, with adjusted prevalence estimates of 0.33 to 2.51 per 10,000. The annual incidence ranged between 0.22 and 7.4 per 100,000 population.

A 2023 study found the incidence rate in 24 European Union countries was 3.90 per 100,000 person-years from 2013 to 2018, rising from 3.70 in 2013 to 4.00 in 2018 (average annual percent change 1.74%).

In Italy, prevalence rates varied between 2.6 to 24.3 per 100,000 person-year using algorithm 1, and incidence rates between 1.25 and 3.77 per 100,000 person-years.

In Poland's Silesian Voivodeship, the standardized incidence rate increased between 2006-2010, ranging from 2.9-3.8/100,000 population.

Asia-Pacific

Adjusted prevalence estimates ranged from 0.57 to 4.51 per 10,000 in Asia-Pacific countries. In Taiwan, from 2011 to 2019, the annual standardized incidence rates increased from 1.66 to 11.35 per 100,000, while prevalence rates increased from 1.98 to 27.25 per 100,000.

In Korea, the incidence rate was 1.7 per 100,000 based on the 2011 ATS/ERS/JRS/ALAT statement. South Korea had the highest incidence and prevalence estimates globally.

Other Regions

Studies from South America found much lower rates (0.4-1.2 cases per 100,000 per year). In large populated areas such as Brazil, Russia, India, and China (the BRIC region), there may be approximately 2 million people living with IPF.

Demographic Patterns

IPF prevalence and incidence increase with age and are higher among males. Patients aged 61 years or older, those with GERD, and former smokers were at significantly greater risk of developing IPF.

Study Design Parameters

Study Design Parameters and Endpoints in Key IPF Trials

Primary Endpoints

• Forced vital capacity (FVC) is the most common primary endpoint in IPF trials as it's the best surrogate for mortality
• Studies show a strong association between FVC decline and mortality over 52 weeks
• A greater rate of decline in FVC % predicted and lower current FVC % predicted values are associated with increased mortality risk
• The PRECISIONS trial uses a composite primary endpoint of time to 10% relative FVC decline, first respiratory hospitalization, lung transplantation, or death

Secondary Endpoints

• Safety and tolerability data are primary endpoints in early-phase trials
• Clinical functional and radiological status assessments serve as exploratory secondary endpoints
• Quantitative lung fibrosis (QLF) scores from HRCT images show utility as efficacy endpoints
• Death plus hospitalization can serve as a composite endpoint to reduce sample size requirements
• Patient-reported outcome scores and treatment-emergent adverse events are used in trials like PRECISIONS
• Acute exacerbation of IPF (AE-IPF) is considered an important endpoint

Study Design Considerations

• Cohort enrichment strategies substantially impact sample size requirements
• Domiciliary spirometry (home-based) permits more frequent FVC measurement than hospital-based assessment
• Daily home spirometry shows excellent correlation with hospital readings and rate of decline is highly predictive of outcome at 3, 6, and 12 months
• Daily FVC may be valuable as a primary endpoint in short proof-of-concept studies

Patient Selection Parameters

• Common inclusion criteria include FVC > 50% and DLCO > 35% of predicted values
• Reversible airflow limitation occurs in approximately 9.1% of IPF patients
• Risk factors for acute exacerbation include rapid %VC decline and high baseline AaDO2

Key Trials

• INPULSIS™: Phase III, randomized, double-blind studies comparing nintedanib 150 mg twice daily with placebo

• Primary endpoint: annual rate of FVC decline

• Secondary endpoints: St. George's Respiratory Questionnaire score and time to first acute exacerbation

• Enrolled 1066 patients in 24 countries

• INBUILD/INBUILD-ON: Assessed nintedanib in progressive pulmonary fibrosis

• Showed nintedanib slowed FVC decline versus placebo

• Safety profile characterized mainly by gastrointestinal events, primarily diarrhea

• STRIVE-IPF: Phase IIb trial comparing therapeutic plasma exchange, rituximab, and IVIG to treatment as usual in AE-IPF patients

• Primary endpoint: six-month survival

• Bexotegrast trial: Phase-2a multicenter trial randomizing participants to receive bexotegrast or placebo

• Primary endpoint: treatment-emergent adverse events

Emerging Approaches

• RIsk Stratification scorE (RISE) combines physiological parameters, patient-reported dyspnea, and exercise capacity
• Future trials may use an oncological approach with combination of therapies
• Experts anticipate changes in clinical trial endpoints and a more inclusive approach for IPF diagnosis