The prognosis and development of pulmonary hypertension in idiopathic diffuse interstitial lung fibrosis.

The prognosis of patients with idiopathic diffuse interstitial lung fibrosis is extremely variable and depends mainly on the presence and degree of pulmonary arterial hypertension. The incidence of pulmonary arterial hypertension in idiopathic diffuse interstitial lung fibrosis is not exactly known. We concluded from our study that in nonselected symptomatic patients about 50% have normal pulmonary arterial pressure and that advanced pulmonary arterial hypertension (over 30 mmHg) is present in about 10% of cases. The development of pulmonary arterial hypertension in idiopathic diffuse interstitial lung fibrosis, though generally slow, is very different in individual cases. We noted fast development of advanced pulmonary arterial hypertension within 2-3 years as well as stabilized normal pressure for 20 years or more. Further behaviour of pulmonary arterial pressure may not be safely predicted from any value in a first functional examination except in patients with initial advanced pulmonary arterial hypertension; they all either maintain or even increase their pulmonary arterial pressure and their 3-year mortality is over 50%. It is concluded that the knowledge of haemodynamic data not only improves our understanding of idiopathic diffuse interstitial lung fibrosis, but also enables us to determine the prognosis with a fair amount of accuracy.