Acute exacerbation of idiopathic pulmonary fibrosis: role of Chlamydophila pneumoniae infection

Idiopathic Pulmonary Fibrosis and Post-COVID-19 Lung Fibrosis: Links and Risks

Idiopathic pulmonary fibrosis (IPF) is considered the paradigmatic example of chronic progressive fibrosing disease; IPF does not result from a primary immunopathogenic mechanism, but immune cells play a complex role in orchestrating the fibrosing response. These cells are activated by pathogen-associated or danger-associated molecular patterns generating pro-fibrotic pathways or downregulating anti-fibrotic agents. Post-COVID pulmonary fibrosis (PCPF) is an emerging clinical entity, following SARS-CoV-2 infection; it shares many clinical, pathological, and immune features with IPF. Similarities between IPF and PCPF can be found in intra- and extracellular physiopathological pro-fibrotic processes, genetic signatures, as well as in the response to antifibrotic treatments. Moreover, SARS-CoV-2 infection can be a cause of acute exacerbation of IPF (AE-IPF), which can negatively impact on IPF patients’ prognosis. In this narrative review, we explore the pathophysiological aspects of IPF, with particular attention given to the intracellular signaling involved in the generation of fibrosis in IPF and during the SARS-CoV-2 infection, and the similarities between IPF and PCPF. Finally, we focus on COVID-19 and IPF in clinical practice.

Acute exacerbations in children's interstitial lung disease

INTRODUCTION

Acute exacerbations (AEs) increase morbidity and mortality of patients with chronic pulmonary diseases. Little is known about the characteristics and impact of AEs on children's interstitial lung disease (chILD).

METHODS

The Kids Lung Register collected data on AEs, the clinical course and quality of life (patient-reported outcomes - PRO) of rare paediatric lung diseases. Characteristics of AEs were obtained.

RESULTS

Data of 2822 AEs and 2887 register visits of 719 patients with chILD were recorded. AEs were characterised by increased levels of dyspnoea (74.1%), increased respiratory rate (58.6%) and increased oxygen demand (57.4%). Mostly, infections (94.4%) were suspected causing an AE. AEs between two register visits revealed a decline in predicted FEV1 (median -1.6%, IQR -8.0 to 3.9; p=0.001), predicted FVC (median -1.8%, IQR -7.5 to 3.9; p=0.004), chILD-specific questionnaire (median -1.3%, IQR -3.6 to 4.5; p=0.034) and the physical health summary score (median -3.1%, IQR -15.6 to 4.3; p=0.005) compared with no AEs in between visits. During the median observational period of 2.5 years (IQR 1.2-4.6), 81 patients died. For 49 of these patients (60.5%), mortality was associated with an AE.

CONCLUSION

This is the first comprehensive study analysing the characteristics and impact on the clinical course of AEs in chILD. AEs have a significant and deleterious effect on the clinical course and health-related quality of life in chILD.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Acute exacerbation is a major cause of morbidity and mortality in patients with idiopathic pulmonary fibrosis. Although the real nature of it is still not clear and there is no proven effective therapy, progress has been made since the consensus definition and diagnostic criteria were proposed. The trial results of several new innovative therapies in idiopathic pulmonary fibrosis have suggested a potential for benefit in acute exacerbation of idiopathic pulmonary fibrosis, leading to double blind randomized clinical trials in this area. This article reviews the present knowledge on acute exacerbation of idiopathic pulmonary fibrosis, focusing on the triggering factors and treatment.

The impact of SARS-COV2 pandemic on the management oF IPF patients: Our narrative experience

Background

The SARS-CoV-2 pandemic has changed the health-care systems around the world in a remarkable way. We describe the strategies adopted to cope with the limitations imposed by the pandemic to the access to health care by patients diagnosed with idiopathic Pulmonary Fibrosis (IPF).

Material and methods

We conducted a retrospective observational analysis including IPF patients under antifibrotic drugs (nintedanib and pirfenidone) that accessed to the Outpatient clinic of the University of Palermo, Italy. Patients received a phone number and an email address in case of any urgency and a virtual meeting was settled up monthly.

Results

40 patients (M/F: 30/10) were followed up, 33 under nintedanib treatment, 7 under pirfenidone. Among patients under nintedanib, 1 patient reported high fever (T max 39 °C) and purulent sputum with no sign of infections, 1 had hemoptysis that was spontaneously resolved. 2 patients accessed to the emergency department for the worsening of dyspnea; 5 patients had diarrhea that resolved with symptomatic drugs in few days. 3 patients had an increase of alkaline phosphatase levels, leading to the withdrawal of the antifibrotic drug for 15 days, and subsequent normalization of the plasmatic levels. Among patients under pirfenidone, one subject had an increase of ferritin serum levels with no symptoms. The remaining subjects were in stable clinical conditions. None of the patients reported hospitalization or exacerbations, and did not experience antifibrotic withdrawal.

Conclusions

We were able to demonstrate that by implementing alternative ways to monitor the disease, patients did not incur in increased rates of acute exacerbations or higher frequency of side effects and antifibrotic treatment withdrawal.

Systematic review and meta-analysis of prognostic factors of acute exacerbation of idiopathic pulmonary fibrosis

OBJECTIVE

To clarify prognostic factors of acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF).

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

Medline, Embase and Science Citation Index Expanded were searched from 2002 through 1 March 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

The review included primary studies addressing the association between the outcomes such as all-cause mortality of AE of IPF and its potential prognostic factors, which were designated as any clinical information related to the outcomes.

DATA EXTRACTION AND SYNTHESIS

Two reviewers extracted relevant data independently and assessed risk of bias. Univariate results were pooled using a random-effect model if at least three studies were available. Prognostic factors were determined based on significant and consistent results on both univariate and multivariate analyses in the majority of studies.

RESULTS

Out of a total of 6763 articles retrieved, 37 were eligible and 31 potential prognostic factors for all-cause mortality were selected. Each study was subject to certain methodological shortcomings. The following five factors were statistically significant by a meta-analysis of univariate results, which was confirmed by multivariate analysis, that is, Acute Physiology and Chronic Health Evaluation (APACHE) II score (HR 1.10, 1.01 to 1.19), partial pressure of arterial oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratio (ORs 0.99 in two studies and HRs 0.31 and 0.99 in two studies, respectively), lactate dehydrogenase (LDH) (HRs 1.002, 1.003, 1.01 and 1.02), white blood cell (WBC) count (OR 1.38, 1.04 to 1.83) and oxygen therapy before AE (HRs 3.68, 1.05 to 12.9 and 2.34, 1.04 to 5.28) (multivariate analysis, 95% CI).

CONCLUSIONS

APACHE II score, PaO₂/FiO₂ ratio, LDH, WBC count and oxygen therapy before AE were deemed as prognostic factors of AE of IPF. Although there are some methodological limitations in this study, these findings are reliable due to consistent results by both univariate and multivariate analyses.

PROSPERO REGISTRATION NUMBER

CRD42018106172.

Study protocol: exploring the efficacy of cyclophosphamide added to corticosteroids for treating acute exacerbation of idiopathic pulmonary fibrosis; a randomized double-blind, placebo-controlled, multi-center phase III trial (EXAFIP)

Background

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease, with a median survival of 2–3 years and variable natural history, characterized by gradual and progressive deterioration. Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is a severe complication, associated with poor survival and a mortality > 50%. To date, no treatment has proven effective in AE-IPF, with cyclophosphamide (CYC) the only therapy suggested to be effective on survival, primarily based on retrospective series. Considering the high fatality rates of AE-IPF, evaluating the efficacy of immunosuppressive agents in a randomized controlled trial proves crucial, as the results could significantly impact treatment and prognosis of AE-IPF.

Methods

The EXAFIP study is a French national multicenter double-blind placebo-controlled randomized trial. Its primary objective is to evaluate the efficacy of CYC compared to placebo on early survival in patients treated with corticosteroids. We hypothesize that adding CYC to high-dose corticosteroids would reduce 3-month mortality in AE-IPF patients. The primary outcome is all-cause mortality rate at Month 3; secondary objectives are to evaluate the efficacy of CYC compared to placebo on overall survival at Months 6 and 12, respiratory disease-specific mortality, respiratory morbidity, and chest high-resolution computed tomography features, and to determine prognostic factors in AE-IPF and compare the safety of the two treatment arms during 6 months’ follow-up.

Discussion

There is an urgent unmet clinical need for effective AE-IPF treatment. The EXAFIP study is the first large Phase III placebo-controlled randomized trial evaluating the efficacy and safety of CYC added to corticosteroids in treating AE-IPF. The results of this study could significantly impact treatment strategy and prognosis of AE-IPF.

Trial registration

Clinical trials, NCT02460588; Date: June 2, 2015, prospectively; Issue date: 14/11/2017; Protocole Amendment Number: 03.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Acute exacerbation (AEx) of idiopathic pulmonary fibrosis (IPF) is a clinically important complication of IPF that carries a high morbidity and mortality. In the last decade we have learned much about this event, but there are many remaining questions: What is it? Why does it happen? How can we prevent it? How can we treat it? This chapter attempts to summarize and update our current understanding of the epidemiology, etiology, and management of acute exacerbation of IPF and point out areas where additional data are needed.

Acute exacerbation of idiopathic pulmonary fibrosis: a 10-year single-centre retrospective study

Introduction

In 2016, an international working group proposed a revised definition and new diagnostic criteria for the acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF). Based on these criteria, AE-IPF was diagnosed regardless of the presence or absence of a known trigger and categorised as triggered (T-AE) or idiopathic (I-AE) AE-IPF. However, the clinical characteristics of the newly defined AE-IPF and clinical differences between T-AE and I-AE are unresolved.

Methods

We retrospectively analysed 64 patients with AE-IPF (I-AE (42), T-AE (22)) admitted to our hospital over a 10- year period.

Results

I-AE and T-AE cases did not show differences in in-hospital and long-term outcomes (in-hospital mortality: I-AE 52.4%, T-AE 59.1%, p=0.61; long-term mortality: p=0.68). In the I-AE group, significantly more patients received corticosteroid therapy before an AE (I-AE 35.7%, T-AE 4.5%; p=0.01). Significantly more patients in the T-AE group had lung cancer (I-AE 7.1%, T-AE 59.1%, p<0.001). I-AE occurred more frequently in winter while T-AE did not show seasonality. The white blood cell (WBC) count and haemoglobin (Hb) level were independent predictors of in-hospital deaths in I-AE (WBC: OR 1.87; 95% CI 1.09 to 4.95, p=0.01; Hb: OR 0.26, 95%  CI 0.04 to 0.78, p=0.01) but not T-AE.

Discussion

With the introduction of new criteria for AE-IPF, a retrospective study over a 10-year period showed a lack of prognostic difference between I-AE and T-AE. The WBC count and Hb level predicted in-hospital outcome in I-AE cases.

Acute Exacerbation in Interstitial Lung Disease

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has been defined as an acute, clinically significant deterioration that develops within less than 1 month without obvious clinical cause like fluid overload, left heart failure, or pulmonary embolism. Pathophysiologically, damage of the alveoli is the predominant feature of AE-IPF which manifests histopathologically as diffuse alveolar damage and radiologically as diffuse, bilateral ground-glass opacification on high-resolution computed tomography. A growing body of literature now focuses on acute exacerbations of interstitial lung disease (AE-ILD) other than idiopathic pulmonary fibrosis. Based on a shared pathophysiology it is generally accepted that AE-ILD can affect all patients with interstitial lung disease (ILD) but apparently occurs more frequently in patients with an underlying usual interstitial pneumonia pattern. The etiology of AE-ILD is not fully understood, but there are distinct risk factors and triggers like infection, mechanical stress, and microaspiration. In general, AE-ILD has a poor prognosis and is associated with a high mortality within 6–12 months. Although there is a lack of evidence based data, in clinical practice, AE-ILD is often treated with a high dose corticosteroid therapy and antibiotics. This article aims to provide a summary of the clinical features, diagnosis, management, and prognosis of AE-ILD as well as an update on the current developments in the field.

Recent lessons learned in the management of acute exacerbation of idiopathic pulmonary fibrosis

Recognising recent advances, the definition and diagnostic criteria for acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) have been updated by an international working group. The new definition describes any acute, clinically significant respiratory deterioration (both idiopathic and triggered events) characterised by evidence of new widespread alveolar abnormality. The new criteria require a previous or concurrent diagnosis of IPF, an acute worsening or development of dyspnoea typically less than 1 month in duration, chest imaging evidence on computed tomography (CT) of new bilateral ground-glass opacity and/or consolidation superimposed on a background imaging pattern of usual interstitial pneumonia not fully explained by cardiac failure or fluid overload. Due to high in-hospital mortality rates, current treatment guidelines say that the majority of patients with AE-IPF should not receive mechanical ventilation. However, new data suggest that the prognosis may have improved. This modest improvement in overall survival seen in more recent studies may be the result of differences in the diagnostic criteria, study design, baseline clinical risk factors and/or improvements in management. Based on our updated knowledge of possible preventive and therapeutic measures, including mechanical ventilation and pharmacological therapies, the current approach to the treatment of AE-IPF requires careful decision-making.

Recent preventive and therapeutic measures for acute exacerbation of IPF may modestly improve short-term survivalhttp://ow.ly/n6GK30e8mN5

Elevated serum D-dimer level is associated with an increased risk of acute exacerbation in interstitial lung disease

BACKGROUND

Early recognition of patients with interstitial lung disease (ILD) who have an increased risk of developing acute exacerbation (AE) or preclinical AE may be clinically useful, since AE is associated with poor outcome and preventive measures would be of interest to ILD researchers. This study evaluated the relationship between elevated serum D-dimer level (≥0.4 mcg/mL) and subsequent AE or preclinical AE in patients with ILD.

METHODS

This single-center, retrospective study was performed from October 2009 through September 2015 in patients with ILD who were ≥18 years old and had idiopathic pulmonary fibrosis, other idiopathic interstitial pneumonias, chronic hypersensitivity pneumonitis, ILD related to collagen tissue disease, or combined pulmonary fibrosis/emphysema. The primary outcome measure was AE development within three months from each D-dimer measurement. The secondary outcome measures were respiratory-related hospitalization, all-cause hospitalization, venous thromboembolism (VTE), and all-cause mortality within three months.

RESULTS

A total of 263 patients (mean age, 64.1 years) with 374 D-dimer measurements (median, 0.44 mcg/mL) were included. The risk of developing AE was significantly higher in patients with elevated serum D-dimer level (adjusted odds ratio: 10.46; 95% CI: 1.24-88.11; p = 0.03). Patients with elevated serum D-dimer level had increased risk for respiratory-related hospitalization, all-cause hospitalization, VTE, and all-cause mortality. The other factors predictive for AE were home oxygen therapy, increased serum lactate dehydrogenase, decreased FVC, and decreased FEV_1.0.

CONCLUSIONS

Elevated serum D-dimer is associated with the risk of developing AE. Serum D-dimer may be used as a prognostic marker to predict AE or recognize preclinical AE.

The Role of Infection in Interstitial Lung Diseases: A Review

Interstitial lung disease (ILD) comprises an array of heterogeneous parenchymal lung diseases that are associated with a spectrum of pathologic, radiologic, and clinical manifestations. There are ILDs with known causes and those that are idiopathic, making treatment strategies challenging. Prognosis can vary according to the type of ILD, but many exhibit gradual progression with an unpredictable clinical course in individual patients, as seen in idiopathic pulmonary fibrosis and the phenomenon of "acute exacerbation"(AE). Given the often poor prognosis of these patients, the search for a reversible cause of respiratory worsening remains paramount. Infections have been theorized to play a role in ILDs, both in the pathogenesis of ILD and as potential triggers of AE. Research efforts thus far have shown the highest association with viral pathogens; however, fungal and bacterial organisms have also been implicated. This review aims to summarize the current knowledge on the role of infections in the setting of ILD.

Use of biologics to treat acute exacerbations and manage disease in asthma, COPD and IPF

A common feature of chronic respiratory disease is the progressive decline in lung function. The decline can be indolent, or it can be accelerated by acute exacerbations, whereby the patient experiences a pronounced worsening of disease symptoms. Moreover, acute exacerbations may also be a marker of insufficient disease management. The underlying cause of an acute exacerbation can be due to insults such as pathogens or environmental pollutants, or the cause can be unknown. For each acute exacerbation, the patient may require medical intervention such as rescue medication, or in more severe cases, hospitalization and ventilation and have an increased risk of death. Biologics, such as monoclonal antibodies, are being developed for chronic respiratory diseases including asthma, COPD and IPF. This therapeutic approach is particularly well suited for chronic use based on the route and frequency of delivery and importantly, the potential for disease modification. In recent clinical trials, the frequency of acute exacerbation has often been included as an endpoint, to help determine whether the investigational agent is impacting disease. Therefore the significance of acute exacerbations in driving disease, and their potential as a marker of disease activity and progression, has recently received much attention. There is also now a need to standardize the definition of an acute exacerbation in specific disease settings, particularly as this endpoint is increasingly used in clinical trials to also assess therapeutic efficacy. Moreover, specifically targeting exacerbations may offer a new therapeutic approach for several chronic respiratory diseases.

Acute exacerbation of idiopathic pulmonary fibrosis: shifting the paradigm

The goal of this review is to summarise the clinical features, management, and prognosis of acute exacerbations of idiopathic pulmonary fibrosis (AE-IPF). AE-IPF has previously been defined based on clinical and radiological features that include the subacute onset of dyspnoea, bilateral ground glass changes on chest high-resolution computed tomography, and the absence of an identifiable aetiology. The annual incidence of AE-IPF is typically reported at 5–15%, but is less common in mild disease. Features of diffuse alveolar damage are present when a biopsy is performed. Idiopathic pulmonary fibrosis (IPF) patients with acute respiratory worsening are often initially treated with high dose corticosteroids and antimicrobials; however, there are no clear data to support these therapies, and the short-term mortality of AE-IPF is ∼50%. Recent studies have shown that the features and prognosis of AE-IPF are similar to other causes of acute respiratory worsening, including infection, aspiration, air pollution and mechanical injury to the alveolar epithelium. Based on this emerging evidence, we propose a novel approach to the classification of acute respiratory worsening events in patients with IPF that focuses on clinical and radiological findings consistent with an underlying pathobiology of diffuse alveolar damage.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Acute exacerbation of idiopathic pulmonary fibrosis (IPF) is a clinically important complication of IPF that carries a high morbidity and mortality. In the last decade, we have learned much about this event, but there are many remaining questions: What is it? Why does it happen? How can we prevent it? How can we treat it? This chapter attempts to summarize our current understanding of the epidemiology, etiology, and management of acute exacerbation of IPF and point out areas where additional data are sorely needed.

Acute exacerbation of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive and ultimately fatal disease, the clinical course of which in individual patients is highly variable. Sudden deterioration of a patient's respiratory condition during a stable course is not uncommon. Many cases of uncertain etiology have been called acute exacerbation (AEx) of IPF, under the assumption of sudden acceleration of the underlying disease process. In recent years, several studies have reported the clinical significance of AEx-IPF. In 2007 Collard and colleagues created a Consensus Perspective, which proposed consensus definition and standard diagnostic criteria. This review primarily discusses studies performed after this Consensus Perspective.

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is a devastating, age-related lung disease of unknown cause that has few treatment options. This disease was once thought to be a chronic inflammatory process, but current evidence indicates that the fibrotic response is driven by abnormally activated alveolar epithelial cells (AECs). These cells produce mediators that induce the formation of fibroblast and myofibroblast foci through the proliferation of resident mesenchymal cells, attraction of circulating fibrocytes, and stimulation of the epithelial to mesenchymal transition. The fibroblast and myofibroblast foci secrete excessive amounts of extracellular matrix, mainly collagens, resulting in scarring and destruction of the lung architecture. The mechanisms that link idiopathic pulmonary fibrosis with ageing and aberrant epithelial activation are unknown; evidence suggests that the abnormal recapitulation of developmental pathways and epigenetic changes have a role. In this Seminar, we review recent data on the clinical course, therapeutic options, and underlying mechanisms thought to be involved in the pathogenesis of idiopathic pulmonary fibrosis.

[Management of acute exacerbations of pulmonary fibrosis]

INTRODUCTION

Acute exacerbation of idiopathic pulmonary fibrosis (IPF) is defined by an acute worsening of the respiratory status without any identified cause.

STATE OF THE ART

IPF is the most frequent type of chronic interstitial pneumonia. In general, its course is a progressive worsening with a median survival at 3 years after diagnosis. Acute exacerbation is now recognized as a severe complication of IPF. It develops most often within less than 1 month and is characterized by a worsening of dyspnoea associated with the occurrence of new images on chest radiograph. Its diagnosis requires the exclusion of an identified cause for acute deterioration such as pulmonary embolism, bronchopulmonary infection, left heart failure or pneumothorax. The treatment of acute exacerbations of IPF is not well standardized and even though isolated cases of therapeutic success have been reported, its prognosis remains poor. In the most severe cases, mechanical ventilation is generally considered to be ineffective, thus leading most often to a conservative management strategy with no transfer to ICU. However, this attitude is now being questioned since it is now potentially possible to perform an urgent lung transplantation in some patients at least in several countries, including France.

CONCLUSION

Acute exacerbation of IPF is a severe complication of IPF, but its optimal management is not yet clearly defined.

Clinical course and prediction of survival in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, life-threatening, interstitial lung disease of unknown etiology. The median survival of patients with IPF is only 2 to 3 years, yet some patients live much longer. Respiratory failure resulting from disease progression is the most frequent cause of death. To date we have limited information as to predictors of mortality in patients with IPF, and research in this area has failed to yield prediction models that can be reliably used in clinical practice to predict individual risk of mortality. The goal of this concise clinical review is to examine and summarize the current data on the clinical course, individual predictors of survival, and proposed clinical prediction models in IPF. Finally, we will discuss challenges and future directions related to predicting survival in IPF.

Gene expression profiles of acute exacerbations of idiopathic pulmonary fibrosis

RATIONALE

The molecular mechanisms underlying acute exacerbations of idiopathic pulmonary fibrosis (IPF) are poorly understood. We studied the global gene expression signature of acute exacerbations of IPF.

OBJECTIVES

To understand the gene expression patterns of acute exacerbations of IPF.

METHODS

RNA was extracted from 23 stable IPF lungs, 8 IPF lungs with acute exacerbation (IPF-AEx), and 15 control lungs and used for hybridization on Agilent gene expression microarrays. Functional analysis of genes was performed with Spotfire and Genomica. Gene validations for MMP1, MMP7, AGER, DEFA1-3, COL1A2, and CCNA2 were performed by real-time quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry and in situ terminal deoxynucleotidyltransferase dUTP nick end-labeling assays were performed on the same tissues used for the microarray. ELISA for alpha-defensins was performed on plasma from control subjects, patients with stable IPF, and patients with IPF-AEx.

MEASUREMENTS AND MAIN RESULTS

Gene expression patterns in IPF-AEx and IPF samples were similar for the genes that distinguish IPF from control lungs. Five hundred and seventy-nine genes were differentially expressed (false discovery rate < 5%) between stable IPF and IPF-AEx. Functional analysis of these genes did not indicate any evidence of an infectious or overwhelming inflammatory etiology. CCNA2 and alpha-defensins were among the most up-regulated genes. CCNA2 and alpha-defensin protein levels were also higher and localized to the epithelium of IPF-AEx, where widespread apoptosis was also detected. alpha-Defensin protein levels were increased in the peripheral blood of patients with IPF-AEx.

CONCLUSIONS

Our results indicate that IPF-AEx is characterized by enhanced epithelial injury and proliferation, as reflected by increases in CCNA2 and alpha-defensins and apoptosis of epithelium. The concomitant increase in alpha-defensins in the peripheral blood and lungs may suggest their use as biomarkers for this disorder.