Idiopathic pulmonary fibrosis: tracking the true occurrence is challenging

TrxR/Trx inhibitor butaselen ameliorates pulmonary fibrosis by suppressing NF-κB/TGF-β1/Smads signaling

Pulmonary fibrosis is highly lethal with limited treatments. Butaselen (BS) is an inhibitor of thioredoxin reductase (TrxR)/thioredoxin (Trx) with anti-tumor activity. However, its impact on pulmonary fibrosis and the involved mechanisms remain unclear. Here, we demonstrate that BS is a potential drug for the treatment of pulmonary fibrosis. Specifically, BS can inhibit pulmonary fibrosis both in vitro and in vivo, with comparable efficacy and enhanced safety when compared with pirfenidone. BS and dexamethasone display a synergistic effect in inhibiting pulmonary fibrosis both in vitro and in vivo. Mechanistic studies reveal that BS can inhibit the TrxR activity during pulmonary fibrosis. RNA-sequencing analysis identifies that genes of ECM-related signaling pathways are notably affected by BS. BS can not only inhibit the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and reduce pulmonary fibrosis-related inflammation, but also reduce NF-κB-activated transcriptional expression of transforming growth factor-β1 (TGF-β1), which leads to the inactivation of Smad2/Smad3 and decrease of collagen formation and fibrosis. Moreover, the knockdown of Trx1 with siRNA can also inhibit NF-κB/TGF-β1/Smads signaling. In conclusion, the TrxR/Trx inhibitor butaselen can suppress pulmonary fibrosis by inhibiting NF-κB/TGF-β1/Smads signaling.

Lifestyle, Genetic Susceptibility, and the Risk of Idiopathic Pulmonary Fibrosis: A Large Prospective Cohort Study

BACKGROUND

Lifestyle is an important contributor of age-related chronic disease, but the association between lifestyle and the risk of idiopathic pulmonary fibrosis (IPF) remains unknown. The extent to which genetic susceptibility modifies the effects of lifestyle on IPF also remains unclear.

RESEARCH QUESTION

Is there a joint effect or interaction of lifestyle and genetic susceptibility on the risk of developing IPF?

STUDY DESIGN AND METHODS

This study included 407,615 participants from the UK Biobank study. A lifestyle score and a polygenic risk score were constructed separately for each participant. Participants were then classified into three lifestyle categories and three genetic risk categories based on the corresponding score. Cox models were fitted to assess the association of lifestyle and genetic risk with the risk of incident IPF.

RESULTS

With favorable lifestyle as the reference group, intermediate lifestyle (hazard ratio, 1.384; 95% CI, 1.218-1.574) and unfavorable lifestyle (hazard ratio, 2.271; 95% CI, 1.852-2.785) were significantly associated with an increased risk of IPF. For the combined effect of lifestyle and polygenic risk score, participants with unfavorable lifestyle and high genetic risk had the highest risk of IPF (hazard ratio, 7.796; 95% CI, 5.482-11.086) compared with those with favorable lifestyle and low genetic risk. Moreover, approximately 32.7% (95% CI, 11.3-54.1) of IPF risk could be attributed to the interaction of an unfavorable lifestyle and high genetic risk.

INTERPRETATION

Exposure to unfavorable lifestyle significantly increased the risk of IPF, particularly in those with high genetic risk.

New therapeutic approaches against pulmonary fibrosis

Pulmonary fibrosis is the end-stage change of a large class of lung diseases characterized by the proliferation of fibroblasts and the accumulation of a large amount of extracellular matrix, accompanied by inflammatory damage and tissue structure destruction, which also shows the normal alveolar tissue is damaged and then abnormally repaired resulting in structural abnormalities (scarring). Pulmonary fibrosis has a serious impact on the respiratory function of the human body, and the clinical manifestation is progressive dyspnea. The incidence of pulmonary fibrosis-related diseases is increasing year by year, and no curative drugs have appeared so far. Nevertheless, research on pulmonary fibrosis have also increased in recent years, but there are no breakthrough results. Pathological changes of pulmonary fibrosis appear in the lungs of patients with coronavirus disease 2019 (COVID-19) that have not yet ended, and whether to improve the condition of patients with COVID-19 by means of the anti-fibrosis therapy, which are the questions we need to address now. This review systematically sheds light on the current state of research on fibrosis from multiple perspectives, hoping to provide some references for design and optimization of subsequent drugs and the selection of anti-fibrosis treatment plans and strategies.

Air pollutants, genetic susceptibility and risk of incident idiopathic pulmonary fibrosis

BACKGROUND

Air pollutants are considered as non-negligible risk factors of idiopathic pulmonary fibrosis (IPF). However, the relationship between long-term air pollution and the incidence of IPF is unknown. Our objective was to explore the associations of air pollutants with IPF risk and further assess the modification effect of genetic susceptibility.

METHODS

We used land-use regression model estimated concentrations of nitrogen dioxide (NO₂), nitrogen oxides (NO _x ) and particulate matter (fine particulate matter with diameter <2.5 μm (PM_2.5) and particulate matter with diameter <10 μm (PM₁₀)). The polygenic risk score (PRS) was constructed using 13 independent single nucleotide polymorphisms. Cox proportional hazard models were used to evaluate the associations of air pollutants with IPF risk and further investigate the modification effect of genetic susceptibility. Additionally, absolute risk was calculated.

RESULTS

Among 433 738 participants from the UK Biobank, the incidence of IPF was 27.45 per 100 000 person-years during a median follow-up of 11.78 years. The adjusted hazard ratios of IPF for each interquartile range increase in NO₂, NO _x and PM_2.5 were 1.11 (95% CI 1.03-1.19), 1.07 (95% CI 1.01-1.13) and 1.09 (95% CI 1.02-1.17), respectively. PM_2.5 had the highest population attribution risk, followed by NO _x and NO₂. There were additive interactions between NO₂, NO _x and PM_2.5 and genetic susceptibility. Participants with a high PRS and high air pollution had the highest risk of incident IPF compared with those with a low PRS and low air pollution (adjusted hazard ratio: NO₂ 3.94 (95% CI 2.77-5.60), NO _x 3.08 (95% CI 2.21-4.27), PM_2.5 3.65 (95% CI 2.60-5.13) and PM₁₀ 3.23 (95% CI 2.32-4.50)).

CONCLUSION

Long-term exposures to air pollutants may elevate the risk of incident IPF. There are additive effects of air pollutants and genetic susceptibility on IPF risk.

A mitochondrial-targeted near-infrared fluorescent probe for visualizing the fluctuation of hypochlorite acid in idiopathic pulmonary fibrosis mice

Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory disease destroying lungs irreversibly with high mortality rates. There are challenges in diagnosing IPF and treating it at an early stage. Mounting evidence suggests that hypochlorous acid (HClO) can help in diagnosing inflammation and relevant conditions. Pulmonary fibrosis is linked to the mitochondrial oxidative stress where excessive HClO production is a key molecular mechanism. Measuring mitochondrial HClO levels assists in the investigations of how the mitochondrial oxidative stress affects IPF. Herein, NIR-PTZ-HClO was developed and optimized as a probe for detecting fluctuations in HClO concentrations of cells and mice models through near-infrared (NIR) fluorescence. The probe featured large Stokes shift of 150 nm, NIR turn-on signal at 650 nm, high sensitivity (45-fold) and quick HClO detection (2 s). The probe is selective for HClO in the presence of range of other analytes. NIR-PTZ-HClO visualized both endogenous and exogenous HClO in living cells (RAW264.7, H460 and A549). The probe monitored HClO in mice models with IPF and moreover the HClO profile could be tracked during the IPF process. The probe also detected precipitous decrease in HClO levels in IPF mice treated with OFEV. NIR-PTZ-HClO probe has thus the potential for earlier diagnosis of lung fibrosis, thereby improving the treatment efficacy.

Matrix metalloproteinases inhibitors in idiopathic pulmonary fibrosis: Medicinal chemistry perspectives

Idiopathic pulmonary fibrosis (IPF) is a lethal disease with limited therapeutic options and a particularly poor prognosis. Matrix metalloproteinases (MMPs), promising targets for the treatment of IPF, have been identified as playing a pivotal role in IPF. Although the pathological processes of MMPs and IPF have been verified, there are no MMP inhibitors for the treatment of IPF in the clinic. In this review, we will present the latest developments in MMP inhibitors, including pharmacophores, binding modes, selectivity and optimization strategies. In addition, we will also discuss the future development direction of MMP inhibitors based on emerging tools and techniques.

The development of HEC-866 and its analogues for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with a typical survival time between three to five years. Two drugs, pirfenidone and nintedanib have been approved for the treatment of IPF, but they have limited efficacy. Thus, the development of new drugs to treat IPF is an urgent medical need. In this paper we report the discovery of a series of orally active pyrimidin-4(3H)-one analogs which exhibit potent activity in in vitro assays. Among them, HEC-866 showed promising efficacy in rat IPF models. Since HEC-866 also had good oral bioavailability, a long half-life and favorable long-term safety profiles, it was selected for further clinical evaluation.

National Registry of Interstitial Lung Disease from Pakistan

Introduction

Interstitial lung disease (ILD) is a heterogeneous group of over 200 parenchymal lung diseases with a myriad of etiologies. Interstitial lung disease registries from around the world show varying prevalence and incidence of these diseases. The aim of this study was to determine the epidemiology and characteristics of ILD in Pakistan.

Methods

This web-based registry, which is the first multicenter registry of ILD from Pakistan, recruited patients from 10 centers of five major cities between January 2016 and March 2019.

Results

A total of 744 patients were enrolled in the registry. The five most frequent ILDs were idiopathic pulmonary fibrosis (IPF) 34.4%, hypersensitivity pneumonitis (HP) - 17.7%, idiopathic nonspecific interstitial pneumonitis (iNSIP) - 16.8%, connective tissue disease-associated ILD (CTD-ILD) - 16.3%, and sarcoidosis - 9.1%.

Conclusion

Idiopathic pulmonary fibrosis is the most prevalent ILD in Pakistan, followed by HP and iNSIP. An ongoing prospective registry with longitudinal follow-up will help us further elaborate on the clinical characteristics, treatment, and survival outcome of patients with ILD.

Hirsutella sinensis mycelium regulates autophagy of alveolar macrophages via TLR4/NF-κB signaling pathway

Background: Hirsutella sinensis mycelium (HSM) has potent anti-pulmonary fibrotic activities and has been proposed as an effective treatment for idiopathic pulmonary fibrosis. Macrophages are the main innate immune cells in the lung tissue, playing key roles in pulmonary fibrosis repair and homeostasis. Excessive macrophage autophagy plays a vital role in pulmonary fibrosis. The protective effect of HSM on macrophages of bleomycin (BLM)-induced pulmonary fibrotic mice remain unclear. Methods: In this study, we collected lung tissue and bronchoalveolar lavage fluid (BALF) samples from pulmonary fibrotic mice. Meanwhile, alveolar macrophages were isolated and murine macrophage RAW264.7 cell line was cultured for further study of HSM autophagy. Results: First, we found that HSM decreased the number of autophagosomes, as well as the levels of LC3B and ATG5, and increased the protein level of P62 during the development of pulmonary fibrosis. Meanwhile, HSM reduced alveolar macrophages infiltration into the BALF and inhibited their accumulation in the fibrotic lung tissue. Flow cytometry analysis showed that HSM administration inhibited the autophagy marker LC3B expression in CD11bloCD11chi alveolar macrophages in BLM-induced lung fibrosis without affecting CD11bhiCD11clo interstitial macrophages. Transmission electron microscopy and JC-1 staining for mitochondrial membrane potential of alveolar macrophages also verified that the HSM significantly decreased autophagy in the alveolar macrophages of BLM-treated mice. In vitro, autophagosomes-lysosome fusion inhibitor chloroquine (CQ) was pre-incubated with RAW264.7 cells, and HSM reduced CQ-induced autophagosomes accumulation. TLR4 signaling inhibitor CLI095 reversed the above effects, suggesting HSM could reduce the cumulation of autophagosomes dependent on TLR4. Furthermore, lipopolysaccharide (LPS)-stimulated TLR4-related autophagy was significantly inhibited by HSM treatment. In addition, the protein expressions of TLR4 and phospho-NF-κB p65 were markedly inhibited in cells treated with HSM. Conclusions: These results indicated that HSM could inhibit the autophagy of alveolar macrophages through TLR4/NF-κB signaling pathway to achieve anti-fibrotic effect.

Ophiocordyceps lanpingensis polysaccharides attenuate pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with growing prevalence. Currently available therapies for treating IPF are not desirable due to the limited efficacy and multiple side effects. Ophiocordyceps lanpingensis is one strain of entomogenous fungi, which has been collected from the eastern part of the Himalayas. This study revealed that O. lanpingensis polysaccharides (OLP) could attenuate bleomycin (BLM) induced lung fibrosis in mice. Results showed that OLP treatments significantly reduced BLM-induced collagen deposition and decreased the accumulation of macrophages. The oxidative stress of the lung was alleviated by OLP. The expression levels of pro-inflammatory and pro-fibrogenic factors in OLP groups were also decreased compared with those in the BLM group, which might explain the improved alveolar integrity and function in the OLP treated groups. Our findings indicated that OLP treatment could alleviate pulmonary fibrosis progression mainly through reducing the recruitment of macrophages to the lungs.

Epidemiology and Clinico-radiological features of Interstitial Lung Diseases

Objective:

The literature on interstitial lung diseases is limited. The aim of this research was to make this entity of diseases more understandable to clinicians and general population of the region of Pakistan.

Methods:

We conducted a cross-sectional study on 253 Pakistani subjects who are a part of the hospital-based registry of JPMC. We performed statistical analyses on SPSS version 22.0. We included patients above 15 years of age who exhibited clinical clues and radiological signs of ILD during March 2016 through February 2018 and excluded those who were on tuberculosis treatment, suspected to be suffering from post-infection bronchiectasis, expectant females or had failed to follow-up.

Results:

There was a 2:3 male to female ratio. Mean age was 49.0±13.2 years. Majority were non-smokers. Idiopathic Pulmonary Fibrosis (IPF) was the commonest ILD (38.8%) followed by Non-Specific Interstitial Pneumonitis (NSIP) (15.1%). Most patients presented with dyspnea and dry cough and about half were clubbed (47.3%). Substantial IPF cases (52.6%) were suffering from GERD symptoms.

Conclusion:

IPF and NSIP were the major ILDs, GERD was the only predictor of IPF. This entity of lung diseases needs to be explored further to identify patterns of presentation and to make diagnosis at a manageable stage.

Viral Infection Increases the Risk of Idiopathic Pulmonary Fibrosis: A Meta-Analysis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease with a poor prognosis. Although many factors have been identified that possibly trigger or aggravate IPF, such as viral infection, the exact cause of IPF remains unclear. Until now, there has been no systematic review to assess the role of viral infection in IPF quantitatively.

OBJECTIVE

This meta-analysis aims to present a collective view on the relationship between viral infection and IPF.

METHODS

We searched studies reporting the effect of viral infection on IPF in the PubMed, Embase, Cochrane Library, Web of Science, and Wiley Online Library databases. We calculated ORs with 95% CIs to assess the risk of virus in IPF. We also estimated statistical heterogeneity by using I² and Cochran Q tests and publication bias by using the funnel plot, Begg test, Egger test, and trim-and-fill methods. Regression, sensitivity, and subgroup analyses were performed to assess the effects of confounding factors, such as sex and age.

RESULTS

We analyzed 20 case-control studies from 10 countries with 1,287 participants. The pooled OR of all viruses indicated that viral infection could increase the risk of IPF significantly (OR, 3.48; 95% CI, 1.61-7.52; P = .001), but not that of exacerbation of IPF (OR, 0.99; 95% CI, 0.47-2.12; P = .988). All analyzed viruses, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8), were associated with a significant elevation in the risk of IPF, except human herpesvirus 6 (HHV-6).

CONCLUSIONS

The presence of persistent or chronic, but not acute, viral infections, including EBV, CMV, HHV-7, and HHV-8, significantly increases the risk of developing IPF, but not exacerbation of IPF. These findings imply that viral infection could be a potential risk factor for IPF.

Differences Between COPD Patients of a Pulmonary Rehabilitation Program According to the mMRC Dyspnea Scale

Background:

The modified Medical Research Council scale (mMRC) is a standardized measure of the effect of dyspnea on the activities of the daily life of patients suffering from Chronic Obstructive Pulmonary Disease (COPD). The aim of this study was to determine the differences in the quality of life, tolerance to effort and symptoms among patients with COPD with lower (mMRC 0-1) and greater symptoms (mMRC ≥2).

Methods:

Cross-sectional study that included patients admitted to a pulmonary rehabilitation program and who were classified into 2 groups: a group containing the less symptomatic patients and another group with the more symptomatic ones. We collected these patients’ sociodemographic, clinical, anthropometric, anxiety, depression and quality of life (SGRQ) data. Likewise, the subjects performed the 6-minute walk test (6MWT). Finally, we measured the multidimensional BODE index score.

Results:

130 subjects were included, 35 presenting an mMRC of 0 to1 and 95 having an mMRC ≥ 2, with an age of 70.87 ± 9.45 years old. The 6MWT distance, the VO2e, the total score of SGRQ, and its domains of activities and impact showed significant differences between the groups (p <0.05). Significant correlations were found in the group presenting an mMRC of 0-1 between the mMRC and the FEV1 (p = 0.028), and in the group with an mMRC ≥2 for the FVC (p = 0.031), the 6MWT distance (p = 0.000), the VO2e (p = 0.010) and the BODE index (p = 0.000).

Conclusion:

Patients with an mMRC of 0 to1 had better results in the 6MWT, the VO2e and the SGRQ in comparison with the most symptomatic ones.

Mortality from idiopathic pulmonary fibrosis: a temporal trend analysis in Brazil, 1979-2014

Objective:

To analyze mortality from idiopathic pulmonary fibrosis (IPF) in Brazil over the period 1979-2014.

Methods:

Microdata were extracted from the Brazilian National Ministry of Health Mortality Database. Only deaths for which the underlying cause was coded as International Classification of Diseases version 9 (ICD-9) 515 or 516.3 (until 1995) or as ICD version 10 (ICD-10) J84.1 (from 1996 onward) were included in our analysis. Standardized mortality rates were calculated for the 2010 Brazilian population. The annual trend in mortality rates was analyzed by joinpoint regression. We calculated risk ratios (RRs) by age group, time period of death, and gender, using a person-years denominator.

Results:

A total of 32,092 deaths were recorded in the study period. Standardized mortality rates trended upward, rising from 0.24/100,000 population in 1979 to 1.10/100,000 population in 2014. The annual upward trend in mortality rates had two inflection points, in 1992 and 2008, separating three distinct time segments with an annual growth of 2.2%, 6.8%, and 2.4%, respectively. The comparison of RRs for the age groups, using the 50- to 54-year age group as a reference, and for the study period, using 1979-1984 as a reference, were 16.14 (14.44-16.36) and 6.71 (6.34-7.12), respectively. Men compared with women had higher standardized mortality rates (per 100,000 person-years) in all age groups.

Conclusion:

Brazilian IPF mortality rates are lower than those of other countries, suggesting underdiagnosis or underreporting. The temporal trend is similar to those reported in the literature and is not explained solely by population aging.

Changing causes of death for patients with chronic respiratory disease in England, 2005-2015

BACKGROUND

Chronic respiratory diseases (CRD) are common, are increasing in prevalence, and cause significant morbidity and mortality worldwide. However, we have limited knowledge on causes of death of patients with CRD in the general population.

OBJECTIVE

We evaluated mortality rates and causes of death over time in patients with CRD.

METHODS

We used linked primary care and mortality data to determine mortality rates and the most common causes of death in people with CRD (including asthma, bronchiectasis, COPD and interstitial lung diseases (ILD)) during 2005-2015 in England.

RESULTS

We identified 558 888 patients with CRD (451 830 asthma, 137 709 COPD, 19 374 bronchiectasis, 10 745 ILD). The age-standardised mortality rate of patients with CRD was 1607 per 100 000 persons (asthma=856, COPD=1503, ILD=2609, bronchiectasis=1463). CRD mortality was overall 54% higher than the general population. A third of patients with CRD died from respiratory-related causes. Respiratory-related mortality was constant, while cardiovascular-related mortality decreased significantly over time. COPD accounted for the majority of respiratory-related deaths (66% overall) in all patient groups except ILD.

CONCLUSIONS

Patients with CRD continue to experience substantial morbidity and mortality due to respiratory diseases. Disease-modifying intervention strategies are needed to improve outcomes for patients with CRD.

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disease characterized by progressive lung scarring and the histological picture of usual interstitial pneumonia (UIP). It is associated with increasing cough and dyspnoea and impaired quality of life. IPF affects ∼3 million people worldwide, with incidence increasing dramatically with age. The diagnostic approach includes the exclusion of other interstitial lung diseases or overlapping conditions and depends on the identification of the UIP pattern, usually with high-resolution CT; lung biopsy might be required in some patients. The UIP pattern is predominantly bilateral, peripheral and with a basal distribution of reticular changes associated with traction bronchiectasis and clusters of subpleural cystic airspaces. The biological processes underlying IPF are thought to reflect an aberrant reparative response to repetitive alveolar epithelial injury in a genetically susceptible ageing individual, although many questions remain on how to define susceptibility. Substantial progress has been made in the understanding of the clinical management of IPF, with the availability of two pharmacotherapeutic agents, pirfenidone and nintedanib, that decrease physiological progression and likely improve progression-free survival. Current efforts are directed at identifying IPF early, potentially relying on combinations of biomarkers that include circulating factors, demographics and imaging data.

Interstitial Lung Disease in India. Results of a Prospective Registry

RATIONALE

Interstitial lung disease (ILD) is a heterogeneous group of acute and chronic inflammatory and fibrotic lung diseases. Existing ILD registries have had variable findings. Little is known about the clinical profile of ILDs in India.

OBJECTIVES

To characterize new-onset ILDs in India by creating a prospective ILD using multidisciplinary discussion (MDD) to validate diagnoses.

METHODS

Adult patients of Indian origin living in India with new-onset ILD (27 centers, 19 Indian cities, March 2012-June 2015) without malignancy or infection were included. All had connective tissue disease (CTD) serologies, spirometry, and high-resolution computed tomography chest. ILD pattern was defined by high-resolution computed tomography images. Three groups independently made diagnoses after review of clinical data including that from prompted case report forms: local site investigators, ILD experts at the National Data Coordinating Center (NDCC; Jaipur, India) with MDD, and experienced ILD experts at the Center for ILD (CILD; Seattle, WA) with MDD. Cohen's κ was used to assess reliability of interobserver agreement.

MEASUREMENTS AND MAIN RESULTS

A total of 1,084 patients were recruited. Final diagnosis: hypersensitivity pneumonitis in 47.3% (n = 513; exposure, 48.1% air coolers), CTD-ILD in 13.9%, and idiopathic pulmonary fibrosis in 13.7%. Cohen's κ: 0.351 site investigator/CILD, 0.519 site investigator/NDCC, and 0.618 NDCC/CILD.

CONCLUSIONS

Hypersensitivity pneumonitis was the most common new-onset ILD in India, followed by CTD-ILD and idiopathic pulmonary fibrosis; diagnoses varied between site investigators and CILD experts, emphasizing the value of MDD in ILD diagnosis. Prompted case report forms including environmental exposures in prospective registries will likely provide further insight into the etiology and management of ILD worldwide.

Incidence and prevalence of idiopathic pulmonary fibrosis in US adults 18–64 years old

We sought to present the epidemiology of idiopathic pulmonary fibrosis (IPF) in adults 18–64 years old in the USA.

From adults aged 18–64 years in a large administrative claims data in 2004–2010, patients with IPF were identified using diagnosis codes. We estimated annual incidence and cumulative prevalence of IPF over time, and examined potential risk factors for the IPF diagnosis.

The annual cumulative prevalence increased steadily in the first few years (from 13.4 cases per 100 000 persons in 2005 to 18.2 cases in 2010 per 100 000 persons), which is likely due to a methodological reason, while the annual incidence of IPF decreased over time (from 7.9 cases per 100 000 person-years in 2005 to 5.8 cases in 2010 per 100 000 person-years). The overall decrease was mainly driven by a decreasing trend in the younger patients (aged 18–44 years), while the incidence in older patients remained stable. Consistent trends were observed in subgroups defined by previously published more restrictive algorithms for diagnosis. Older age and male sex were associated with a higher incidence of disease (p<0.05).

In US adults younger than 65 years, we observed a decreasing incidence of IPF over time which may partially explain the plateau of cumulative prevalence in the last few years of our data.