Epidemiology and distribution of interstitial lung diseases in Turkey

Introduction: There is very few data on the epidemiological features of interstitial lung diseases (ILD) in the literature. These studies on this subject suffer from limited number of patients.

Objective: The goal of this study was to evaluate the epidemiological features of ILD in Turkey.

Methods: Fifty-four investigators, 31 centres in 19 cities from six regions of Turkey, participated in the study. Two thousand two hundred forty-five newly diagnosed patients (51.8% females), led by Turkish Thoracic Society Clinical Problems Study Group, enrolled in this prospective study.

Results: The mean age was 51.8 ± 16.7 years. The mean age among males was 50.5 ± 18.6 years and 53.0 ± 14.6 years among females (P < 0.001). 23.8% of the cases had ILD with known causes, while 39.4% were in granulomatous group, 23.7% were idiopathic, and 4.4% were in the unclassified group. Overall, histopathologically confirmed diagnosis rate was 40.4%. Sarcoidosis was the most common disease (37%), whereas cases with idiopathic pulmonary fibrosis (IPF) constituted 19,9% of patients. 53% of the sarcoidosis patients were females, and the ratio reaches to 75% under 50 years of age (for this group, IPF ratio is %3). In contrast, sarcoidosis and IPF ratios were equal in males (25%). Sarcoidosis was 8% in men over 50, while IPF was %45.

Conclusion: The overall incidence of ILD in Turkey was computed to be 25.8/100,000.