Prevalence Of Subclinical Liver Fibrosis Among Patients With Idiopathic Pulmonary Fibrosis

Rationale Idiopathic pulmonary fibrosis (IPF) is a specific form of progressive fibrosing interstitial pneumonia of unknown cause. Common pathogenic mechanisms with chronic fibrotic disorders involving other organs are likely. Yet, data on the co-existence of subclinical fibrotic disease across multiple organs in patients with IPF are lacking. The present study aimed to investigate the prevalence of subclinical liver fibrosis among patients with IPF. Methods Patients referred to the Center for Rare Lung Disease of the University Hospital of Modena, with a diagnosis of IPF according to recent guidelines and without previous history of liver diseases underwent hepatic transient elastography (FibroScan®), a non-invasive technique measuring liver stiffness, which routinely used for the assessment of hepatic fibrosis in patients with chronic liver diseases. Hepatic fibrotic status is expressed in a scale from 0 (absence of hepatic fibrosis) to 4 (severe liver fibrosis / cirrhosis). Patients with body mass index (BMI) ≥29 (confidence limit of the instrument) were excluded. Patients, in which any degree of hepatic fibrosis was detected, underwent screening for possible secondary causes of liver fibrosis. Results Among 48 IPF patients (34 males, mean age 69 years), 11 (23%) were excluded because of high BMI. In 8 out 37 patients (22%) it was not possible to obtain successful measurements due to the excess of subcutaneous adipose tissue in the chest wall, or narrow intercostal spaces. Thirteen of 37 patients (35%) had abnormal hepatic transient elastography results: 4 patients fell within the range F1-F2 (6.1-7.6 kPa), 6 in F2 (7.4-8.4 kPa), one in F2-F3 (9.5 kPa), 1 in F4 (14.3 kPa) and 1 was identified as probable fibrosis not otherwise classifiable. In all cases, secondary causes of hepatic fibrosis were excluded. Minor impairment of markers of liver injury was found in a minority of patients with liver fibrosis, with AST and ALT values exceeding the threshold value respectively in 2 and 3 patients with liver fibrosis, detected on elastography. Conclusions Over one third of patients in this IPF cohort had a concomitant fibrosing subclinical process in the liver. These preliminary data prompt the need for a large prospective study aimed at clarifying the correlation between the fibrosing processes in the lung and in the liver and the possibility of shared pathogenic mechanisms.