An earlier and more confident diagnosis of idiopathic pulmonary fibrosis

Abstract

A diagnosis of idiopathic pulmonary fibrosis (IPF) has serious implications for the affected individuals, who have a 50% likelihood of dying within 2-3 yrs, an outcome which is worse than many cancers. A swift and accurate diagnosis is imperative, especially as commencing treatment at a relatively early disease stage may have the greatest impact on reducing disease progression. The 2011, IPF guidelines provide updated and simplified IPF diagnostic criteria that may facilitate making a more confident diagnosis. The key investigational tool is high-resolution computed tomography (HRCT). In the presence of the four classical features, that together accurately identify a usual interstitial pneumonia (UIP) pattern, a definitive diagnosis of IPF can be made. When HRCT honeycombing is absent, even in the presence of all other features including traction bronchiectasis, the guidelines provide no designation for this constellation of features that many clinicians and radiologists would regard as consistent with UIP. The diagnostic algorithm suggested by the 2011 guidelines emphasises the importance of multidisciplinary discussion between clinicians, radiologists and pathologists to improve diagnostic confidence. The course of disease in IPF is unpredictable, but the importance of an early diagnosis is clear, as individuals with less severe lung function abnormalities have a better prognosis.

Figure 1.

Prognosis of idiopathic pulmonary fibrosis is worse than nonspecific interstitial pneumonia and other idiopathic interstitial pneumonias. ––––: other idiopathic interstitial pneumonias; ·······: nonspecific interstitial pneumonias; - - - - -: idiopathic pulmonary fibrosis. Reproduced from [8] with permission from the publisher.

Figure 2.

5-yr survival rate of idiopathic pulmonary fibrosis (IPF) is worse than several types of cancer. Data taken from [8,9].

Figure 3.

High-resolution computed tomography image of a typical usual interstitial pneumonia pattern. Black arrows: extensive honeycombing; grey arrows: traction bronchiectasis; arrowheads: reticular opacities.

Figure 4.

Diagnostic algorithm for idiopathic pulmonary fibrosis (IPF). Patients with suspected IPF (i.e. patients with unexplained dyspnoea on exertion and/or cough with evidence of interstitial lung disease (ILD)) should be carefully evaluated for identifiable causes of ILD. In the absence of an identifiable cause for ILD, a high-resolution computed tomography (HRCT) scan demonstrating usual interstitial pneumonia (UIP) pattern is diagnostic of IPF. In the absence of UIP pattern on HRCT, IPF can be diagnosed by the combination of specific HRCT and histopathological patterns. The accuracy of the diagnosis of IPF increases with multidisciplinary discussion (MDD) among ILD experts. ^#: as per table 3. Reproduced from [2] with permission from the publisher.