Unravelling the health and economic burden of interstitial lung diseases in adults in Australia.

BACKGROUND: Interstitial lung diseases (ILD) are a heterogenous group of over 200 disorders affecting the pulmonary interstitium. Although there have been advances in knowledge on ILDs in Australia, the characterisation of the health and economic burden of disease remained largely undetermined until recently. OBJECTIVE: The main objective of this review is to provide a synopsis of health and economic burden of ILDs in Australia, based on recently completed research. DISCUSSION: Recent research has demonstrated that idiopathic pulmonary fibrosis (IPF) is the most frequent ILD in Australia. Incidence and prevalence of IPF have demonstrated an increasing trend over the past decades. Mortality has also increased over the past decades, but has shown a slight decreasing trend recently, since the introduction of antifibrotic medication. Health-related quality of life is poor in patients with IPF, and care is estimated to cost approximately AU$299 million per year in Australia. Early diagnosis and referral to tertiary care is crucial for favourable outcomes, and general practitioners are considerably important to this as the first interface to identify patients at risk and detect early symptoms of ILDs.

Genetics and Genomics of Pulmonary Fibrosis: Charting the Molecular Landscape and Shaping Precision Medicine.

Recent genetic and genomic advancements have elucidated the complex etiology of idiopathic pulmonary fibrosis (IPF) and other progressive fibrotic interstitial lung diseases (ILDs), emphasizing the contribution of heritable factors. This state-of-the-art review synthesizes evidence on significant genetic contributors to pulmonary fibrosis (PF), including rare genetic variants and common single nucleotide polymorphisms (SNPs). The MUC5B promoter variant is unusual, a common SNP that markedly elevates the risk of early and established PF. We address the utility of genetic variation in enhancing understanding of disease pathogenesis, clinical phenotypes, improving disease definitions, and informing prognosis and treatment response. Critical research gaps are highlighted, particularly the underrepresentation of non-European ancestries in PF genetic studies and the exploration of PF phenotypes beyond usual interstitial pneumonia (UIP)/IPF. We discuss the role of telomere length, often critically short in PF, and its link to progression and mortality, underscoring the genetic complexity involving telomere biology genes (TERT, TERC) and others like SFTPC and MUC5B. Additionally, we address the potential of gene-by-environment interactions to modulate disease manifestation, advocating for precision medicine in PF. Insights from gene expression profiling studies and multi-omic analyses highlight the promise for understanding disease pathogenesis and offer new approaches to clinical care, therapeutic drug development, and biomarker discovery. Finally, we discuss the ethical, legal, and social implications of genomic research and therapies in PF, stressing the need for sound practices and informed clinical genetic discussions. Looking forward, we advocate for comprehensive genetic testing panels and polygenic risk scores to improve the management of PF and related ILDs across diverse populations.

Agreement between local and central anti-synthetase antibodies detection: results from the Classification Criteria of Anti-Synthetase Syndrome project biobank.

OBJECTIVES: The CLASS (Classification Criteria of Anti-Synthetase Syndrome) project is a large international multicentre study that aims to create the first data-driven anti-synthetase syndrome (ASSD) classification criteria. Identifying anti-aminoacyl tRNA synthetase antibodies (anti-ARS) is crucial for diagnosis, and several commercial immunoassays are now available for this purpose. However, using these assays risks yielding false-positive or false-negative results, potentially leading to misdiagnosis. The established reference standard for detecting anti-ARS is immunoprecipitation (IP), typically employed in research rather than routine autoantibody testing. We gathered samples from participating centers and results from local anti-ARS testing. As an "ad-interim" study within the CLASS project, we aimed to assess how local immunoassays perform in real-world settings compared to our central definition of anti-ARS positivity. METHODS: We collected 787 serum samples from participating centres for the CLASS project and their local anti-ARS test results. These samples underwent initial central testing using RNA-IP. Following this, the specificity of ARS was reconfirmed centrally through ELISA, line-blot assay (LIA), and, in cases of conflicting results, protein-IP. The sensitivity, specificity, positive likelihood ratio and positive and negative predictive values were evaluated. We also calculated the inter-rater agreement between central and local results using a weighted κ co-efficient. RESULTS: Our analysis demonstrates that local, real-world detection of anti-Jo1 is reliable with high sensitivity and specificity with a very good level of agreement with our central definition of anti-Jo1 antibody positivity. However, the agreement between local immunoassay and central determination of anti-non-Jo1 antibodies varied, especially among results obtained using local LIA, ELISA and "other" methods. CONCLUSIONS: Our study evaluates the performance of real-world identification of anti-synthetase antibodies in a large cohort of multi-national patients with ASSD and controls. Our analysis reinforces the reliability of real-world anti-Jo1 detection methods. In contrast, challenges persist for anti-non-Jo1 identification, particularly anti-PL7 and rarer antibodies such as anti-OJ/KS. Clinicians should exercise caution when interpreting anti-synthetase antibodies, especially when commercial immunoassays test positive for non-anti-Jo1 antibodies.

Drug-induced interstitial lung disease: a narrative review of a clinical conundrum.

INTRODUCTION: Drug-induced interstitial lung disease (DI-ILD) is increasing in incidence, due to the use of many new drugs across a broad range of cancers and chronic inflammatory diseases. The presentation and onset of DI-ILD are variable even for the same drug across different individuals. Clinical suspicion is essential for identifying these conditions, with timely drug cessation an important determinant of outcomes. AREAS COVERED: This review provides a comprehensive and up-to-date summary of epidemiology, risk factors, pathogenesis, diagnosis, treatment, and prognosis of DI-ILD. Relevant research articles from PubMed and Medline searches up to September 2023 were screened and summarized. Specific drugs including immune checkpoint inhibitors, CAR-T cell therapy, methotrexate, and amiodarone are discussed in detail. The potential role of pharmacogenomic profiling for lung toxicity risk is considered. EXPERT OPINION: DI-ILD is likely to be an increasingly important contributor to respiratory disability in the community. These conditions can negatively impact quality of life and patient longevity, due to associated respiratory compromise as well as cessation of evidence-based therapy for the underlying disease. This clinical conundrum is relevant to all areas of medicine, necessitating increased understanding and greater vigilance for drug-related lung toxicity.

Zinpentraxin Alfa for Idiopathic Pulmonary Fibrosis: The Randomized Phase III STARSCAPE Trial.

Rationale: A phase II trial reported clinical benefit over 28 weeks in patients with idiopathic pulmonary fibrosis (IPF) who received zinpentraxin alfa. Objectives: To investigate the efficacy and safety of zinpentraxin alfa in patients with IPF in a phase III trial. Methods: This 52-week phase III, double-blind, placebo-controlled, pivotal trial was conducted at 275 sites in 29 countries. Patients with IPF were randomized 1:1 to intravenous placebo or zinpentraxin alfa 10 mg/kg every 4 weeks. The primary endpoint was absolute change from baseline to Week 52 in FVC. Secondary endpoints included absolute change from baseline to Week 52 in percent predicted FVC and 6-minute walk distance. Safety was monitored via adverse events. Post hoc analysis of the phase II and phase III data explored changes in FVC and their impact on the efficacy results. Measurements and Main Results: Of 664 randomized patients, 333 were assigned to placebo and 331 to zinpentraxin alfa. Four of the 664 randomized patients were never administered study drug. The trial was terminated early after a prespecified futility analysis that demonstrated no treatment benefit of zinpentraxin alfa over placebo. In the final analysis, absolute change from baseline to Week 52 in FVC was similar between placebo and zinpentraxin alfa (-214.89 ml and -235.72 ml; P = 0.5420); there were no apparent treatment effects on secondary endpoints. Overall, 72.3% and 74.6% of patients receiving placebo and zinpentraxin alfa, respectively, experienced one or more adverse events. Post hoc analysis revealed that extreme FVC decline in two placebo-treated patients resulted in the clinical benefit of zinpentraxin alfa reported by phase II. Conclusions: Zinpentraxin alfa treatment did not benefit patients with IPF over placebo. Learnings from this program may help improve decision making around trials in IPF. Clinical trial registered with www.clinicaltrials.gov (NCT04552899).

Multiple serum biomarkers associate with mortality and interstitial lung disease progression in systemic sclerosis.

OBJECTIVES: To investigate the prognostic utility of 28 serum biomarkers in systemic sclerosis (SSc), SSc-associated interstitial lung disease (SSc-ILD) and clinically relevant disease subgroups. METHODS: Participants with sera, high-resolution computed tomography, and lung function within 12 months of baseline were identified from the Australian Scleroderma Cohort Study. Baseline was the time of serum collection. 27 of the prespecified 28 serum biomarkers were analysed and biomarker associations with mortality and ILD progression were investigated in univariable and multivariable analyses, including within disease subgroups and combined with established risk factors for poorer prognosis in SSc. RESULTS: 407 participants were identified, 252 (61.9%) with SSc-ILD. The median follow up after biomarker measurement was 6.31 (3.11-9.22) years. 16 biomarkers were associated with increased mortality. High levels of VCAM-1 were most strongly associated with mortality (HR 3.55; 95%CI 2.37-5.33; p< 0.001). Five additional biomarkers had a HR > 2: SP-D (2.28, 1.57-3.31; p< 0.001), E-selectin (2.19; 1.53-3.14; p< 0.001), IL-6 (2.15 1.50-3.09; p< 0.001), MMP3 (1.42-2.95; p< 0.001) and ET-1 (2.03, 1.40-2.92; p< 0.001). 11 biomarkers were independently associated with mortality following adjustment for sex, age and baseline forced vital capacity (FVC%predicted). Three biomarkers were associated with ILD progression at one year follow up: CXCL4 (OR 2.67, 1.46-4.88; p= 0.001), MMP-1 (2.56, 1.43-4.59; p= 0.002) and ET-1 (2.18, 1.24-3.83; p= 0.007). CONCLUSION: Multiple biomarkers, especially VCAM-1, E-Selectin, SP-D and CXCL4, provide prognostic utility beyond that of established risk factors for patients with SSc.

Disease Behaviour Classification: A pragmatic model for predicting outcomes in Interstitial Lung Disease.

BACKGROUND AND OBJECTIVE: The interstitial lung diseases (ILD) are a heterogenous group of disorders with similar clinical presentation, but widely varying prognoses. The use of a pragmatic disease behaviour classification (DBC), first proposed in international guidelines in 2013, categorises diseases into five behavioural classes based on their predicted clinical course. This study aimed to determine the prognostic utility of the DBC in an ILD cohort. METHODS: Consecutive patients presented at the weekly multidisciplinary meeting (MDM) of a specialist ILD centre were included. MDM consensus was obtained for diagnosis and DBC category (1-5). Baseline and serial clinical and physiological data were collected over the study period (median 3.9 years, range 0-5.4 years). The relationship between DBC and prognostic outcomes was explored. RESULTS: 137 ILD patients, [64 (47%) female] were included with mean age 67.0 ± 1.1 years, baseline FVC% 72.7 ± 1.7, and baseline DLco% 57.8 ± 1.6%. Patients were stratified into DBC by consensus at MDM: DBC1 n = 0 (0%), DBC2 n = 16 (12%), DBC3 n = 10 (7.3%), DBC4 n = 55 (40%), and DBC5 n = 56 (41%). On univariable Cox regression, increasing DBC class was associated with poorer progression-free survival (HR 1.6, 95% CI 1.2-2.0, p < 0.001). On multivariable Cox regression, DBC remained predictive of PFS when combined with age and gender (HR 1.4, 95% CI 1.1-1.9, p = 0.011), baseline FVC% (HR 1.5, 95% CI 1.1-1.8, p = 0.003) and ILD diagnosis (HR 1.6, 95% CI 1.2-2.2, p < 0.0001). CONCLUSION: DBC as determined at ILD multidisciplinary meeting may be a useful prognostic tool for the management of ILD patients.

Treatment of idiopathic pulmonary fibrosis and progressive pulmonary fibrosis: A position statement from the Thoracic Society of Australia and New Zealand 2023 revision.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease leading to significant morbidity and mortality. In 2017 the Thoracic Society of Australia and New Zealand (TSANZ) and Lung Foundation Australia (LFA) published a position statement on the treatment of IPF. Since that time, subsidized anti-fibrotic therapy in the form of pirfenidone and nintedanib is now available in both Australia and New Zealand. More recently, evidence has been published in support of nintedanib for non-IPF progressive pulmonary fibrosis (PPF). Additionally, there have been numerous publications relating to the non-pharmacologic management of IPF and PPF. This 2023 update to the position statement for treatment of IPF summarizes developments since 2017 and reaffirms the importance of a multi-faceted approach to the management of IPF and progressive pulmonary fibrosis.

Mortality surrogates in combined pulmonary fibrosis and emphysema.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) with coexistent emphysema, termed combined pulmonary fibrosis and emphysema (CPFE) may associate with reduced forced vital capacity (FVC) declines compared to non-CPFE IPF patients. We examined associations between mortality and functional measures of disease progression in two IPF cohorts. METHODS: Visual emphysema presence (>0% emphysema) scored on computed tomography identified CPFE patients (CPFE/non-CPFE: derivation cohort n=317/n=183, replication cohort n=358/n=152), who were subgrouped using 10% or 15% visual emphysema thresholds, and an unsupervised machine-learning model considering emphysema and interstitial lung disease extents. Baseline characteristics, 1-year relative FVC and diffusing capacity of the lung for carbon monoxide (D LCO) decline (linear mixed-effects models), and their associations with mortality (multivariable Cox regression models) were compared across non-CPFE and CPFE subgroups. RESULTS: In both IPF cohorts, CPFE patients with ≥10% emphysema had a greater smoking history and lower baseline D LCO compared to CPFE patients with <10% emphysema. Using multivariable Cox regression analyses in patients with ≥10% emphysema, 1-year D LCO decline showed stronger mortality associations than 1-year FVC decline. Results were maintained in patients suitable for therapeutic IPF trials and in subjects subgrouped by ≥15% emphysema and using unsupervised machine learning. Importantly, the unsupervised machine-learning approach identified CPFE patients in whom FVC decline did not associate strongly with mortality. In non-CPFE IPF patients, 1-year FVC declines ≥5% and ≥10% showed strong mortality associations. CONCLUSION: When assessing disease progression in IPF, D LCO decline should be considered in patients with ≥10% emphysema and a ≥5% 1-year relative FVC decline threshold considered in non-CPFE IPF patients.

Occupational interstitial lung diseases.

Millions of workers are exposed to substances known to cause occupational interstitial lung diseases (ILDs), particularly in developing countries. However, the burden of the disease is likely to be underestimated due to under-recognition, under-reporting or both. The diagnosis of occupational ILD requires a high level of suspicion and a thorough occupational history, as occupational and non-occupational ILDs may be clinically, functionally and radiologically indistinguishable, leading to delayed diagnosis and inappropriate management. A potential occupational aetiology should always be considered in the differential diagnosis of ILD, as removal from the workplace exposure, with or without treatment, is a key therapeutic intervention and may lead to significant improvement. In this article, we provide an overview of the 'traditional' inorganic dust-related ILDs but also address idiopathic pulmonary fibrosis and the immunologically mediated chronic beryllium disease, sarcoidosis and hypersensitivity pneumonitis, with emphasis on the importance of surveillance and prevention for reducing the burden of these conditions. To this end, health-care professionals should be specifically trained about the importance of occupational exposures as a potential cause of ILD.

Pulmonary hypertension associated with lung disease: new insights into pathomechanisms, diagnosis, and management.

Patients with chronic lung diseases, particularly interstitial lung disease and chronic obstructive pulmonary disease, frequently develop pulmonary hypertension, which results in clinical deterioration, worsening of oxygen uptake, and an increased mortality risk. Pulmonary hypertension can develop and progress independently from the underlying lung disease. The pulmonary vasculopathy is distinct from that of other forms of pulmonary hypertension, with vascular ablation due to loss of small pulmonary vessels being a key feature. Long-term tobacco exposure might contribute to this type of pulmonary vascular remodelling. The distinct pathomechanisms together with the underlying lung disease might explain why treatment options for this condition remain scarce. Most drugs approved for pulmonary arterial hypertension have shown no or sometimes harmful effects in pulmonary hypertension associated with lung disease. An exception is inhaled treprostinil, which improves exercise capacity in patients with interstitial lung disease and pulmonary hypertension. There is a pressing need for safe, effective treatment options and for reliable, non-invasive diagnostic tools to detect and characterise pulmonary hypertension in patients with chronic lung disease.

Long-term exposure to low concentrations of air pollution and decline in lung function in people with idiopathic pulmonary fibrosis: Evidence from Australia.

BACKGROUND AND OBJECTIVE: Little is known about the association between ambient air pollution and idiopathic pulmonary fibrosis (IPF) in areas with lower levels of exposure. We aimed to investigate the impact of air pollution on lung function and rapid progression of IPF in Australia. METHODS: Participants were recruited from the Australian IPF Registry (n = 570). The impact of air pollution on changes in lung function was assessed using linear mixed models and Cox regression was used to investigate the association with rapid progression. RESULTS: Median (25th-75th percentiles) annual fine particulate matter (<2.5 µm, PM2.5 ) and nitrogen dioxide (NO2 ) were 6.8 (5.7, 7.9) µg/m3 and 6.7 (4.9, 8.2) ppb, respectively. Compared to living more than 100 m from a major road, living within 100 m was associated with a 1.3% predicted/year (95% confidence interval [CI] -2.4 to -0.3) faster annual decline in diffusing capacity of the lungs for carbon monoxide (DLco). Each interquartile range (IQR) of 2.2 µg/m3 increase in PM2.5 was associated with a 0.9% predicted/year (95% CI -1.6 to -0.3) faster annual decline in DLco, while there was no association observed with NO2 . There was also no association between air pollution and rapid progression of IPF. CONCLUSION: Living near a major road and increased PM2.5 were both associated with an increased rate of annual decline in DLco. This study adds to the evidence supporting the negative effects of air pollution on lung function decline in people with IPF living at low-level concentrations of exposure.

Novel diagnostic techniques in interstitial lung disease.

Research into novel diagnostic techniques and targeted therapeutics in interstitial lung disease (ILD) is moving the field toward increased precision and improved patient outcomes. An array of molecular techniques, machine learning approaches and other innovative methods including electronic nose technology and endobronchial optical coherence tomography are promising tools with potential to increase diagnostic accuracy. This review provides a comprehensive overview of the current evidence regarding evolving diagnostic methods in ILD and to consider their future role in routine clinical care.

A Composite Serum Biomarker Index for the Diagnosis of Systemic Sclerosis-Associated Interstitial Lung Disease: A Multicenter, Observational Cohort Study.

OBJECTIVE: In patients with systemic sclerosis (SSc), we investigated composite serum biomarker panels for the diagnosis and risk stratification of SSc-associated interstitial lung disease (SSc-ILD). METHODS: We analyzed 28 biomarkers in 640 participants: 259 patients with SSc-ILD and 179 SSc patients without ILD (Australian Scleroderma Cohort Study), 172 patients with idiopathic pulmonary fibrosis (IPF-controls) (Australian IPF Registry), and 30 healthy controls. A composite index was developed from biomarkers associated with ILD in multivariable analysis derived at empirical thresholds. We evaluated the performance of the index to identify ILD, and specifically SSc-ILD, and its association with lung function, disease extent on radiography, and patient health-related quality of life in derivation and validation cohorts. Biomarkers to distinguish SSc-ILD from IPF-controls were identified. RESULTS: A composite biomarker index, comprising surfactant protein D (SP-D), Ca15-3, and intercellular adhesion molecule 1 (ICAM-1), was strongly associated with SSc-ILD diagnosis, independent of age, sex, smoking history, and lung function (for biomarker index score 3, pooled adjusted odds ratio was 12.72 (95% confidence interval 4.59-35.21) (P < 0.001). The composite index strengthened the performance of individual biomarkers for SSc-ILD identification. In SSc patients, a higher index was associated with worse baseline disease severity (for biomarker index score 3 relative to biomarker index score 0, the adjusted absolute change in forced vital capacity percent predicted was -17.84% and the diffusing capacity for carbon monoxide percent predicted was -20.16%; both P < 0.001). CONCLUSION: A composite serum biomarker index, comprising SP-D, Ca15-3, and ICAM-1, may improve the identification and risk stratification of ILD in SSc patients at baseline.

Mapping EQ5D utilities from forced vital capacity and diffusing capacity in fibrotic interstitial lung disease.

OBJECTIVES: Fibrotic interstitial lung disease (ILD) includes a large group of conditions that lead to scarring of the lungs. The lack of available 5-level EuroQol 5D (EQ5D) data has limited the ability to conduct economic evaluations in ILD. The purpose of this study was to develop and validate a mapping algorithm that predicts EQ5D utilities from commonly collected pulmonary function measurements (forced vital capacity [FVC] and diffusing capacity of the lung for carbon monoxide [DLCO]) in fibrotic ILDs. METHODS: EQ5D utility and pulmonary function measurements from the Canadian Registry for Pulmonary Fibrosis were included. Ordinary least squares (OLS), beta regression, two-part, and tobit models were used to map EQ5D utilities from FVC or DLCO. Model performance was assessed by comparing the predicted and observed utilities. Subgroup analyses were also conducted to test how well models performed across different patient characteristics. The models were then externally validated in the Australian Idiopathic Pulmonary Fibrosis Registry. RESULTS: The OLS model performed as well as other more complex models (root mean squared error: 0.17 for FVC and 0.16 for DLCO). As with the other models, the OLS algorithm performed well across the different subgroups (except for EQ5D utilities < 0.5) and in the external validation cohort. CONCLUSION: We developed a mapping algorithm that predicts EQ5D utilities from FVC and DLCO, with the intent that this algorithm can be applied to clinical trial populations and real-world cohorts that have not prioritized collection of health-related utilities. The mapping algorithm can be used in future economic evaluations of potential ILD therapies.

Sex- and Race-Based Differences in the Treatment of Interstitial Lung Diseases in North America and Australasia.

BACKGROUND: Biological sex, gender, and race are important considerations in patients with interstitial lung diseases (ILDs). RESEARCH QUESTION: Does a patient's sex assigned at birth, and race, influence ILD treatment initiation? STUDY DESIGN AND METHODS: Patients with ILD from three longitudinal prospective registries were compared in this observational study. ILD-related medications included antifibrotics and immunomodulating medications. Race was dichotomized as "White" vs "non-White." Time to treatment initiation was determined from the date of the initial ILD registry visit to the date of first medication initiation. Proportions of treated patients were compared between groups by χ2 test. Cox proportional analysis was used to determine how sex and race were associated with time to treatment initiation stratified by ILD diagnosis. RESULTS: A total of 4,572 patients were included across all cohorts. The proportion of men who received treatment was higher than for women in the Canadian cohort (47% vs 40%; P < .001), and the proportion of White patients who received treatment was also higher compared with non-White patients (46% vs 36%; P < .001). In contrast, the proportion of treated men in the Chicago cohort was lower compared with women (56% vs 64%; P = .005), and that of White patients was lower compared with non-White patients (56% vs 69%; P < .001). No sex- or race-based differences in proportions of patients treated were found in the Australasian cohort. White race was significantly associated with earlier treatment initiation compared with non-White race across diagnoses in the Canadian cohort, whereas the opposite association was found in the Australasian cohort. INTERPRETATION: Sex- and race-based differences exist in the initiation of ILD treatment, with variability across different cohorts in different countries. Reasons for these differences need to be further explored in future studies.

Idiopathic Pulmonary Fibrosis Is Associated with Common Genetic Variants and Limited Rare Variants.

Rationale: Idiopathic pulmonary fibrosis (IPF) is a rare, irreversible, and progressive disease of the lungs. Common genetic variants, in addition to nongenetic factors, have been consistently associated with IPF. Rare variants identified by candidate gene, family-based, and exome studies have also been reported to associate with IPF. However, the extent to which rare variants, genome-wide, may contribute to the risk of IPF remains unknown. Objectives: We used whole-genome sequencing to investigate the role of rare variants, genome-wide, on IPF risk. Methods: As part of the Trans-Omics for Precision Medicine Program, we sequenced 2,180 cases of IPF. Association testing focused on the aggregated effect of rare variants (minor allele frequency ⩽0.01) within genes or regions. We also identified individual rare variants that are influential within genes and estimated the heritability of IPF on the basis of rare and common variants. Measurements and Main Results: Rare variants in both TERT and RTEL1 were significantly associated with IPF. A single rare variant in each of the TERT and RTEL1 genes was found to consistently influence the aggregated test statistics. There was no significant evidence of association with other previously reported rare variants. The SNP heritability of IPF was estimated to be 32% (SE = 3%). Conclusions: Rare variants within the TERT and RTEL1 genes and well-established common variants have the largest contribution to IPF risk overall. Efforts in risk profiling or the development of therapies for IPF that focus on TERT, RTEL1, common variants, and environmental risk factors are likely to have the largest impact on this complex disease.