What is Idiopathic Interstitial Pneumonia With Autoimmune Features?
The European Respiratory Society/American Thoracic Society (ERS/ATS) collaboration has set out guidelines for a type of lung disease called interstitial pneumonia with autoimmune features (IPAF). Their goal was to categorize and describe a specific group of patients suffering from an unexplained kind of interstitial pneumonia. These patients exhibit signs of their bodies attacking their own cells (autoimmunity), but do not meet the criteria for a defined autoimmune disease affecting connective tissue.
Before these guidelines were introduced, research was conducted on a specific subset of interstitial pneumonia without a known cause, which had associations with features suggesting a possible hidden autoimmune condition. Different names and definitions have been suggested for this type of lung disease.
An international expert panel, including thirteen lung disease specialists, four autoimmune disease specialists, one lung imaging expert, and one lung tissue specialist, came together to develop the classifications for IPAF. They based their classifications on three factors: physical signs outside the chest area, the presence of specific autoantibodies (proteins that the body mistakenly creates to attack its own cells), and the lung’s appearance on imaging, tissue analysis findings, and involvement of different compartments of the lungs.
What Causes Idiopathic Interstitial Pneumonia With Autoimmune Features?
Interstitial lung disease (ILD) is a term that encompasses a large number of different conditions that affect the lung tissue. A common example is connective tissue disease-associated lung disease (CTD-ILD). These, along with a condition known as idiopathic pulmonary fibrosis (IPF), make up the majority of ILD cases.
It’s important to note that CTD-ILD normally has a better prognosis than IPF, meaning it is often more treatable and thus its management is different. Because of this, it’s crucial to accurately diagnose the type of ILD a patient has. In fact, up to 30% of newly diagnosed ILD cases are due to CTD-ILD. This highlights why all patients with ILD should be assessed for potential underlying CTD.
Risk Factors and Frequency for Idiopathic Interstitial Pneumonia With Autoimmune Features
Up to 25% of patients with symptoms of a systemic autoimmune disease don’t meet the criteria set by the American College of Rheumatology for connective tissue disease. In contrast, 10-20% of patients with a specific type of lung issue called idiopathic interstitial pneumonia, without a defined connective tissue disease, show symptoms and blood test results that hint at an autoimmune process. Experts around the world have coined different terms for this, such as undifferentiated connective tissue disease-associated lung disease, lung-dominant connective tissue disease, and autoimmune featured Interstitial Lung Disease (ILD). They use different criteria and terms that largely overlap…
- Estimating the occurrence and prevalence rates of Interstitial Lung Disease (ILD) is difficult.
- There are several registries specifically for ILD to help understand it better.
- It’s estimated there are about 30 new cases of ILD for every 100,000 people per year.
- The total number of people living with ILD at any given time is about 80.9 out of 100,000 in males and 67.2 out 100,000 in females every year.
- The prevalence of a specific form of ILD called idiopathic interstitial pneumonia with autoimmune features (IPAF) varies between 7% to 34% among all Interstitial Lung diseases in the population.
- This variation depends on the population studied and the characteristics of the patients recruited.
- People suffering from IPAF are typically 60-65 years old and there’s no gender bias.
- However, some studies have reported a lower average age of 55 years and a higher occurrence in white non-smoking women.
The profile of IPAF patients is different from those with ILD associated with connective tissue diseases (CTD-ILD), who are mainly younger females, and from patients with a type of lung disease called idiopathic pulmonary fibrosis (IPF), who tend to be older males. IPAF patients are more often smokers or ex-smokers. This could be due to the fact that about 30% of IPAF cases show a usual interstitial pneumonia pattern. This is unlike patients with undifferentiated connective tissue disease-related lung damage, where the condition is likely linked with different criteria.
Signs and Symptoms of Idiopathic Interstitial Pneumonia With Autoimmune Features
Interstitial lung disease (ILD) typically starts with progressive shortness of breath during physical activity, a constant cough that doesn’t produce mucus, or lung symptoms linked to another condition like a connective tissue disease. Before there were clear diagnostic criteria for a type of ILD called idiopathic interstitial pneumonia with autoimmune features (IPAF), four different terms were used to describe variations of ILD:
- Undifferentiated CTD-ILD
- Undifferentiated connective tissue disease—with a strict definition
- Lung-dominant connective tissue disease
- Autoimmune-featured interstitial lung disease (AIF-ILD)
It was only after a consensus paper by ERS/ATS in 2015 that specific criteria for diagnosing IPAF were suggested. These criteria required evidence of IPAF from imaging studies or tissue samples, a full clinical evaluation to rule out other possible causes of lung inflammation, and features that are found in but not sufficient to diagnose a specific CTD.
To be considered as a case of IPAF, the three basic requirements need to be fulfilled, as well as at least one feature from at least two of the following categories:
- Clinical domain (specific physical indicators)
- Serological domain (specific autoantibodies in the blood)
- Morphologic domain (specific features seen in chest imaging studies, tissue samples, or involvement of multiple parts of the lung)
Studies have shown that there is a significantly higher number of patients meeting the criteria in the serological and clinical domains. It was found that between 47 and 63% of IPAF patients demonstrated at least one clinical sign. The most common signs were cold-induced color change in fingers or toes (Raynaud phenomenon), unusually rough, cracked skin on the hands (“mechanic’s hands”), and purple or red skin patches over the knuckles (Gottron sign).
Testing for Idiopathic Interstitial Pneumonia With Autoimmune Features
For patients that might have a connective tissue disease (CTD), thanks to their specific symptoms, doctors will usually examine the health issues in three areas: clinical, serological, and morphological.
Clinical Domain: This involves certain physical signs, which alone aren’t enough to diagnose a CTD, but they suggest the presence of one. These physical signs may include skin cracking or ulcers on fingers, inflamed joints, stiffness in multiple joints lasting more than an hour in the morning, changes in skin color in response to cold or stress (known as Raynaud’s phenomenon), tiny red spots on the palm of the hand (palmar telangiectasia), swelling of the fingers not due to injury, and a noticeable hardened skin rash on the back side of the fingers. However, in this stage, it is advised that these signs should be examined by a healthcare provider, as they require professional expertise.
Serological Domain: This involves looking at the patient’s blood for specific autoantibodies which are connected to CTD. Some of these autoantibodies include antinuclear antibodies and rheumatoid factor. However, non-specific inflammation markers like erythrocyte sedimentation rate or C-reactive protein aren’t considered.
Morphological Domain: This is further sub-divided into three parts: radiographic, pathologic, and multi-compartment. The radiographic part assesses patterns from high-resolution chest scans that include non-specific interstitial pneumonia, organizing pneumonia, and lymphocytic interstitial pneumonia. The pathological part involves checking tissue specimens for non-specific interstitial pneumonia, organizing pneumonia, interstitial lymphoid aggregates, or diffuse lymphoplasmacytic infiltrate. Finally, the multi-compartment aspect looks for manifestations like unexplained pericardial or pleural effusion or thickening, pulmonary vasculopathy, and intrinsic airways disease.
These domains are part of the diagnostic process for CTDs that helps healthcare professionals decide if a patient has a CTD or not, based on their symptoms, antibody production and their body’s physical response to these conditions.
Treatment Options for Idiopathic Interstitial Pneumonia With Autoimmune Features
There is currently some uncertainty regarding whether there should be a separate treatment plan for idiopathic interstitial pneumonia with autoimmune features (IPAF) – a type of lung disease. The information we currently have about its treatment is limited to a collection of individual patient case studies, and we need more research to pinpoint the most effective treatment for this group of patients. However, as with other lung diseases, patients with IPAF are advised to participate in pulmonary rehabilitation, get long-term oxygen supplementation if they need it, and treat any existing gastroesophageal reflux (a condition where stomach acid frequently flows up into the tube connecting your mouth and stomach).
So far, there have been no clinical trials showing the benefits of using interventions to modify the immune response (immune-modulating treatments) in IPAF cases. However, doctors consider previous studies on lung diseases associated with connective tissue disorders (CTD-ILD) when deciding how to treat IPAF. One study suggested that intravenous pulse cyclophosphamide, a medication designed to suppress the immune system and decrease inflammation, might help to stabilize lung function. In the same study, it was found that people with IPAF who have progressive fibrosis (scarring) may not find corticosteroids and immunosuppressive drugs helpful since their condition behaves more like idiopathic pulmonary fibrosis (IPF), a type of chronic lung disease that causes scarring of the lungs.
Another, larger study looked at the effects of an immunosuppressive drug called mycophenolate (MMF) on 125 patients with CTD-ILD, 19 of whom had IPAF. The study found that MMF was associated with an improvement in forced vital capacity (FVC—a measure of how much air a person can forcefully blow out after a full inhale) in all the patients tested. There have also been a few case series where rituximab, a drug used to treat certain autoimmune diseases and types of cancer, has been beneficial for patients with severe, hard-to-treat interstitial lung diseases, including nine patients with IPAF.
The INBUILD trial hints that a drug named nintedanib might slow the progression of ILD, as seen in the slowing down of the decline in FVC in patients with a chronic form of ILD and a progressively worsening phenotype (observable traits), regardless of their exact ILD diagnosis, and this includes IPAF. Future research will need to investigate the potential benefits of combining immune-suppressive therapy and anti-fibrotic (scarring) drugs in treating IPAF patients.
What else can Idiopathic Interstitial Pneumonia With Autoimmune Features be?
When attempting to diagnose idiopathic interstitial pneumonia with autoimmune features (IPAF), which is a condition that bridges the gap between idiopathic interstitial pneumonia and connective tissue disease-linked interstitial lung disease, it’s essential to consider and rule out these conditions:
- Idiopathic pulmonary fibrosis (IPF)
- Connective tissue disease-associated ILD (CTD-ILD)
- Cryptogenic organizing pneumonia (COP)
- Idiopathic non-specific interstitial pneumonia (NSIP)
- Lymphocytic interstitial pneumonia (LIP)
What to expect with Idiopathic Interstitial Pneumonia With Autoimmune Features
According to research, patients with a condition called idiopathic interstitial pneumonia with autoimmune features (IPAF) appear to fare better than those with a similar condition known as idiopathic pulmonary fibrosis (IPF). However, their prognosis is slightly worse than those suffering from a third related disorder known as connective tissue disease-associated interstitial lung disease (CTD-ILD).
One study found that patients meeting the criteria for IPAF had a slightly lesser survival rate than those with CTD-ILD, but their survival rate was slightly better than those with IPF.
In the same research, when they grouped patients based on the presence of a particular pattern on their lung imaging tests called UIP, they found that IPAF patients without UIP had nearly the same survival rate as those with CTD-ILD. However, those with UIP were seen to have survival rates similar to those with IPF.
Another study found similar results. Here, a modified group of IPAF patients had a survival rate close to the CTD-ILD group and significantly better than the IPF group. Another observation by Collins and team showed that over a year’s time, IPAF patients demonstrated stable lung functions. Similar trends were also observed in CTD-ILD and IPF groups.
As more data becomes available for this category of diseases, we’ll have a better idea about the prognosis.
Possible Complications When Diagnosed with Idiopathic Interstitial Pneumonia With Autoimmune Features
Idiopathic Interstitial Pneumonia with Autoimmune Features (IPAF) is a condition that worsens over time. If it’s not caught or treated early, it can develop into severe lung scarring. There are also various other complications associated with this condition:
- Increased lung scarring over time
- High blood pressure that affects the lungs
- Cor pulmonale, a condition where the right side of the heart is affected because of increased resistance or high blood pressure in the lungs
- Hypoxemic respiratory failure that needs home oxygen
- Depression or anxiety
Preventing Idiopathic Interstitial Pneumonia With Autoimmune Features
If you have a condition known as idiopathic interstitial pneumonia with autoimmune features (IPAF), it’s important for you to understand your disease. This condition affects your lungs and can be influenced by certain aspects of your lifestyle and environment.
Here are some things you can do to help manage your condition:
– Keep your body weight in a healthy range. This can reduce stress on your lungs, making it easier to breathe.
– If you’re a smoker, consider quitting. Smoking can cause damage to your lungs which can make your condition worse.
– Try to avoid exposure to environmental or occupational factors that might intensify your lung disease. This could be certain kinds of dust, smoke, or other irritants in the air.
– Stay up-to-date on your immunizations. Particularly, the pneumococcal vaccine and the annual influenza, or flu, vaccine. These can help protect your lungs from infections that could be particularly harmful due to your condition.
– Participating in pulmonary rehabilitation. This is a program that teaches you exercises and strategies to improve your breathing and overall lung health.
By incorporating these strategies into your lifestyle, you can help slow the progression of your disease and minimize the complications associated with it.
