Update: Further Progress to Helping Patients with Interstitial Lung Disease
Interstitial Lung Disease (ILD) has many lung disorders that fall under that term. One of them Idiopathic Pulmonary Fibrosis (IPF), is the most common of these disorders. Asbestosis is diffuse pulmonary fibrosis resulting in a slowly progressing disease that can take from 15 to 40 years after exposure to be encountered physical symptoms. And while in most developing countries it has been banned, the exposure-related diagnoses are still being cared for.
More than 100 different conditions are grouped under the term interstitial lung disease (ILD). This is a condition that affects the alveolar structures, pulmonary interstitium, and small airways. To reach this diagnosis a combination of clinical, radiological, and pathological criteria must be met. Among this group of lung disorders is idiopathic pulmonary fibrosis being the most common one of the ILD group. Occupational and environmental exposures have been closely associated with the development of ILD. Such exposures are like asbestos, silica, and coal dust. While asbestos use has been banned in most developing countries, the long latency period between exposure and disease onset for asbestos-related diseases are still being treated. Air pollution exposure such as diesel exhaust, tobacco smoking, and other particulate pollutants provide another source of this disorder. ILDs are a group of uncommon disease of the lungs with IPF (idiopathic pulmonary fibrosis) the most studied with updated guidelines for diagnosis and new treatment options (Rivera-Ortega & Molina-Molina, 2019).
Better Understanding of ILD
Idiopathic inflammatory myopathies (IIMs) encompass a group of rare autoimmune diseases that present as muscle weakness and inflammation. But in interstitial lung disease, it is more frequently seen and often along with IIMs. Anti-synthetase syndrome (ASSD), arthritis and interstitial lung disease are more frequently observed and frequently represent the first manifestation of the disease. IIM diagnosis also brings with other testing that needs to be done such as tumor screening; colonoscopy for people over 50 years. Unfortunately, the unmet needs of patients are not included in many treatment plans. For many patients, it is deeply dependent on disease preservation pattern. The standardization from diagnosis to treatment is crucial to really improve the prognosis of these patients. Future treatment goals need to include multidisciplinary stakeholders with patients to discuss options based on growing evidence (Meyer et al, 2019).
In Japan, the University of Tsukuba has found an association between a gene variant and lung disease in the form of systemic vasculitis; particularly prevalent in Japan and illustrating potential of providing a target for future studies and therapies. Many diseases show major differences in their prevalence from one country to another. Interstitial lung disease in one such condition has been linked to a possible genetic role in the pathogenesis of ILD. This study done in Japan found an association between a variant in the MUC5B gene that can lead to a patient with ILD to develop antibody associated with vasculitis. This could benefit affected patients by providing a new therapeutic target. The study also found that seven of eight AAV patients also had ILD. This suggests this variant could become a strong prognostic tool (U. of Tsukuba, 2019).
Occupational lung disease has had a widespread problem of under-reporting of the contracted illness. Epidemiologic data on occupational interstitial lung disease is limited by no standardized diagnostic criteria in Europe. In addition, they have varied doctor awareness and training and the long latency period of asbestos is not well understood by doctors there either. Radiologists should give voice to a clinical suspicion and at the same time recognize patterns of illness that can lead to stories of misunderstood exposures. In the past 10 years, only 21 papers have been written with the concern of under-reporting and the majority of these articles seemed to focus on lung cancer and mesothelioma. The problems of health damage coming from compounds in the workforce have been known for a long time. This problem has been growing with human activities and progress. Technological advances, new sources of exposure are changing the geographical distribution of occupational pathologies. Asbestos is now seen as a risk factor in interstitial lung disease. Exposure is called asbestosis and is common with second-hand exposure of inhaled fibers mostly seen in family members of the worker who worked directly with the substance. It is felt from this study that making the radiologist aware of patients occupational history and the radiologist should have no qualms about notifying the primary doctor when issues are identified (Mazzei et al, 2019).
Further Methods of Diagnosis
The roles of imaging in systemic diseases can vary according to the specific disorder. Computed tomography (CT) may be important in establishing a diagnosis. Sarcoidosis, for example, exhibits nodule formation predominantly in the upper lobes. In some connective tissue diseases have different pulmonary manifestations. Systemic disorders demonstrate a wide variety of manifestations in the chest. Example, the frequency of interstitial lung disease strongly correlates with the presence of anti-Jo-1. Those who are positive for anti-Jo-1, 50% to 70% have ILD; conversely, without the antibodies, ILD drops to 10%. Imaging, especially CT scans play a critical role in the diagnosis of these disorders. In-depth knowledge by doctors and radiologists, of both typical and untypical clinical manifestations, is critical in the multidisciplinary diagnosis and follow-up of patients with these diseases. Vasculitis is classified by the size of the vessels involved and lung disease is most commonly seen with small vessel vasculitis. CT scans show the appearance of multiple cavitary nodules of varying size (Schaefer-Prokop & Elicker, 2019).
Several studies have reported a high prevalence of Obstructive Sleep Apnea in patients with IPF or restrictive end-stage lung disease. Besides known risk factors for OSA like high BMI, reduced static and dynamic volumes for IPF patients and decreased minimal oxygen saturation during sleep for end-stage lung disease (ELSD) patients were associated with higher apnea/hypopnea index (AHI). The aim of this study was to see if the higher incidence of OSA could predict the patient also having fibrotic lung disease (FLD). Forty-nine patients with FLD with a BMI ≤30Kg/m² were studied. Seventy percent of these patients also had a ≥ 5 events/hr. in a correlative model, AHI showed a statistically significant correlation with age, BMI, the duration of immunosuppressant treatment and FEV1 (forced expiratory volume in the first second). Only BMI remained an independent predictor of OSA in a correlation model adjusted for the other statistically meaningful variables. FLD patients, in general, show a prevalence of OSA superior to that of the general population. It is felt a larger and more homogenous (composed of parts or elements that are all the same) studies are needed to repeat the results showing the connection between OSA and lung function impairment and duration of immunosuppressant treatment (Pereiva et al, 2019).
The group ILD is characterized by cellular proliferation, interstitial fibrosis, or a combination of such finding within the alveolar wall not due to infection or cancer. The most common form, IPF, has been showing an increase although it is unclear if that is because of the actual increase in the numbers or if the condition is just better recognized by healthcare workers. IPF is of particular clinical interest because it is often misdiagnosed and managed inappropriately. Clinical finding should consider ILD as part of a differential diagnosis for adults presenting with unexplained exertional dyspnea, chronic dry cough or Velcro-like crackles on examination. In addition, newer testing needs to be conducted; testing like for MUC5B found in IPF. And non-genetic factors that have been identified such as male, older age, cigarette smoker, GERD (gastric esophageal reflux disease), OSA, certain occupational exposures (asbestos), or air pollution. The use of CT imaging in high-risk cohorts has proven to be a very powerful tool in identifying new targetable risk factors possibly leading to preventable interventions (Lederer & Martinez, 2018).
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