Pragmatic treatment decisions in IPF

Unfortunately we still do not have very good treatments for idiopathic pulmonary fibrosis. The antifibrotics that we have (in 2022) only seem slow down the generally inevitable progress of IPF. To complicate matters further, in certain countries (in this example The United Kingdom) there are certain rules that further limit prescribing nintedanib and pirfenidone (the two antifibrotics available). Basically you need to have an FVC of between 50 to 80% of predicted. This means that some patients who are diagnosed early with idiopathic pulmonary fibrosis cannot have the medication that would potentially slow down their disease and buy them more time before respiratory failure becomes inevitable.

This means that many physicians have to take some pragmatic decisions when starting antifibrotics.

Forcing a working diagnosis of IPF as this gives more treatment options

Many clinicians who are fairly convinced that the IPF diagnosis is the most likely will simply go with this diagnosis to allow their patients to access both antifibrotics (including nintedanib and pirfenidone). This may be even in cases when a progressive fibrotic interstitial lung disease diagnosis is actually plausible and a potential cause may be found if enough tests are run.

Unfortunately for progressive fibrotic ILD, only nintedanib is approved currently. Therefore, by not making a diagnosis of IPF even in questionable cases, many clinicians will feel as if they are not offering all the options available to their patients. I do want to stress that the very word “idiopathic” refers to an undetermined cause. By being put in the situation in which an “idiopathic” diagnosis is offering more options than a specific precise diagnosis it feels like we are taking away from the precision of medicine and we are becoming algorithmic in our diagnostic approach.

Calculating a percent predicted FVC based on GLI predictions

Sometimes when the pulmonary function tests are performed and the predicted values are not based on GLI (Global Lung Function Initiative), some clinicians will recalculate reported % predicted based on GLI. The GLI % predicted FVC value will usually be slightly lower as with other predictions, therefore someone who is borderline above the FVC cut off value (80%) for antifibrotic prescription may actually be within range if GLI predictions are used instead.

Making decisions based on potential treatments available rather than the best diagnosis we can provide

This builds on the first point, where we are trying to find the right diagnosis to provide the treatment rather than finding the right treatment for the right diagnosis. To me this does not seem like great medical care but unfortunately the system in which we operate forces us to make these decisions sometimes.

Even though in most cases this may actually be right, as antifibrotics may slow down any kind of progressive fibrotic interstitial lung disease, it feels that progress in the field is actually stunted because of this approach. Clinicians are not being put in the position to look hard for a precise diagnosis and to establish phenotypic differences between patients who carry the same IPF label. Establishing these phenotypic differences may still be very important to actually provide personalized medicine in the future.

Although I do understand that certain cut off values need to be established in order to prevent inappropriate prescription of antifibrotics, I do worry that this is actually turning out to be counterproductive. Clinicians are forced to follow rules that limit their creativity and their clinical judgment. Patients ultimately receive an imprecise diagnosis with a treatment that’s potentially only “good enough” for them. I worry that many patients with particular phenotypes of “idiopathic” pulmonary fibrosis which may benefit from a more thorough investigation and personalized therapy will be lumped together with everyone else. I wonder – is this in the best interest of our patients?