Diffuse alveolar hemorrhage in coumarin users: a fibrosing interstitial pneumonia trigger?

Fibrosing interstitial pneumonias (IPs) include idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP). It has been suggested that oxidative damage plays a role in the pathophysiology of idiopathic interstitial pneumonias. Diffuse alveolar hemorrhage (DAH) can cause oxidative stress. Accordingly, we hypothesized that episodes of DAH might trigger fibrosing IP development.

Patients using coumarins with confirmed DAH were retrospectively gathered during a 9 year period and reviewed for the development of IPF or fibrosing NSIP.

A total of 65 patients with DAH could finally be included, 31 (48 %) of whom subsequently developed a fibrosing IP. The majority of these 31 patients developed the fibrosing IP within 3 years after DAH confirmation. A total of 41 (63 %) patients died within 3.0 ± 0.9 (range 1.3-4.7) years after the DAH diagnosis had been confirmed. Twenty-two of the deceased (54 %) had finally developed fibrosing IP.

Almost half of the patients with established episodes of DAH developed fibrosing IP; therefore it seems that DAH might be a trigger for the development of fibrosing IP. This observation warrants prospective studies to further evaluate the clinical impact of these findings.