How quickly does a patient with idiopathic pulmonary fibrosis (IPF) receive the correct diagnosis? This is an important question, because delayed access to specialized care is associated with higher mortality in IPF. Unfortunately, the most common symptoms associated with IPF are also symptomatic of a wide variety of other diseases. This complicates early diagnosis in IPF and can cause patients to lose valuable treatment time.
When you google 'shortness of breath' (or the medical term dyspnea), one of the first hits concerns heart attacks. This is understandable: shortness of breath might indeed be a symptom of a cardiac medical condition. But it might also be a symptom of pneumonia, asthma, COPD or, last but not least, an interstitial lung disease (ILD) such as IPF. The fact that one of the most common symptoms of IPF can be symptomatic of many other diseases can cause a delay in receiving the correct diagnosis, which in turn might lead to the initiation of ineffective interventions and the loss of valuable treatment time.
'It's not strange that a general practitioner (GP) might think of a cardiac issue first while considering causes of shortness of breath, says Dutch pulmonologist Marc van Lanen. 'ILDs are a rare disease. When a GP sees an elderly patient with shortness of breath, he will probably listen to their lungs. When he hears bilateral crackles in the lungs, the first thing he will think about is heart failure.' With heart failure, the fluid in the lungs can produce a sound that's similar to the crackles you can hear in the lungs of a patient with IPF. According to Van Lanen, the initial thought of heart failure is justified, because heart failure is much more common than lung fibrosis. 'Often the GP also makes an X-ray, which sometimes shows some abnormalities in the lower lungs. But these abnormalities can look the same as the abnormalities on the X-ray of a patient with heart failure.' Apart from that, a lot of smokers without ILD have some of the same-looking abnormalities in their lungs. 'It's often almost impossible to discern between the non-specific fibrosis of heavy smokers and ILD, based on an X-ray of the lungs. So these abnormalities on X-rays are sometimes not given that much attention.'
It can be hard to detect IPF-specific abnormalities on a X-ray (Source: Wikimedia Commons)
But what about the Velcro sound? Aren't these specific lung crackles the key for early diagnosis of IPF? 'It's true that the crackles in IPF are usually a bit “softer” sounding than in heart failure', Van Lanen says. 'In heart failure, the crackles are often slightly more coarse. But you need to have an extremely trained ear to hear the difference between the two. You don't develop such a sensitive ear as a GP, and seldom as a cardiologist or a pulmonologist.' Van Lanen says that as a pulmonologist, he often sees patients with lung fibrosis only after they have been fully screened by a cardiologist. 'When the cardiologist doesn't find anything and the crackles remain, he starts to think of some form of lung fibrosis.'
It takes a very sensitive ear to distinguish IPF-crackles from crackles from heart failure (Source: Wikimedia Commons)
The patient is then sent to the pulmonologist, where the IPF might also not be immediately discovered. 'The pulmonologist often starts with lung function tests. When there is a clear diffusion disorder and somebody is a heavy smoker, the disorder is often thought of as emphysema. Maybe these patients also have a little COPD, so they are treated with bronchodilators for a while. Which doesn't do them any harm, but it doesn’t benefit them either.' Finally, when the patient keeps getting worse and it's still not clear what the condition exactly is, a CT-scan is made and the ILD can be discovered.
However, even with a CT-scan, the diagnostic process in IPF is still complex. According to Van Lanen, early stages of IPF don't need to show a lot of specific abnormalities on a CT-scan and be hard to distinguish from other forms of ILD. It's only after a high resolution (HR) CT-scan is made and evaluated by a multidisciplinary team, that the diagnosis of IPF can finally be made. 'We diagnose IPF purely on radiological imaging and exclusion of other possible causes', Van Lanen says. 'The final diagnosis is made by a team of experts (pathologists, radiologists, pulmonologists). A biopsy is only performed when the radiological imaging is questionable.'
When the final diagnosis is made, more than two years might have passed since the onset of symptoms
'This can be unfortunate', Van Lanen remarks. 'Because IPF is slowly progressive, there often is also a delay between the first manifestation of symptoms and the first visit to the GP by the patient.' According to Van Lanen, the delay in diagnosis is especially harmful in IPF. 'Other ILDs might not be that malicious and the time lost in the diagnostic process may be less important. But in IPF there is a relatively rapid deterioration of lung function. Anti-fibrotic drugs can slow this deterioration down, but they can't reverse the effect.' The sooner the anti-fibrotic drugs can do their work, the sooner the deterioration of lung function can be restrained. 'Because of diagnosis delay, you might lose a couple of months that could have been spent enjoying a better quality of life', Van Lanen says. 'If you diagnose patients with IPF early, when the dysfunction of the lungs is relatively mild, you give them a longer period with a relative good quality of life. Although you also need to realize that in some patients, the anti-fibrotic drugs do not have any therapeutic effect.'
How could a faster diagnosis of IPF be accomplished? Recently, Finnish researchers published some interesting steps that can be taken to shorten the delay from symptom onset to referral. The researchers think that referral time can be shortened by improving the quality of referral letters and providing ILD information to both doctors and patients. Van Lanen agrees that this can be helpful to shorten the delay. He also points to the option of a better 'profiling' of patients. 'Patients with pulmonary fibrosis are more often male, between 55 and 75, they are often (former) smokers, and they sometimes have had occupational exposure to harmful substances. When you see a patient with that profile, you might think of an ILD sooner.'
However, it will probably remain difficult to identify all ILD patients quickly, Van Lanen thinks. 'It's a rare disease and the patient can also be a woman that has never been exposed to harmful substances. And because heart failure is so much more common than ILDs, GPs will probably keep thinking of that first. I also think that cardiologists refer to us quite easily when their own tests come up negative. So I don't know if a lot of time can be won in the cardiologist's office. But of course, more awareness of ILD's will always be helpful, both with the general public, as well as with healthcare professionals.'