Idiopathic pulmonary fibrosis and pulmonary fibrosis in diffuse systemic sclerosis: two fibroses with different prognoses.

Idiopathic pulmonary fibrosis and diffuse cutaneous systemic sclerosis (dSSc) involve the lung by a fibrotic process. In recent years, there has been increasing awareness that the natural history of these two types of pulmonary fibrosis might be different. The purpose of this study was to compare lung involvement in these two diseases in a prospective fashion in order to address differences in their clinical course. Forty-three consecutive patients, 18 with lone interstitial pulmonary fibrosis (lone IPF) and 25 with dSSc-IPF were evaluated clinically, radiologically and physiologically at the entry into the study and the evolution of their disease was contrasted by survival analysis. Patients with lone IPF compared with dSSc-IPF were characterized by male predominance (p < 0.001), older age at disease onset (p < 0.001), shorter disease duration (p < 0.001), more frequent crackles on auscultation and clubbing (p < 0.001 and p < 0.0001, respectively), more severe dyspnea (p < 0.0001) and more advanced radiological involvement (p < 0.0001). Functional indices presented comparable values and did not reach statistically significant differences except for the values of single breath CO diffusing capacity (p < 0.0001) and the PaO2 (p < 0.01) which was worse in patients with lone IPF. Finally 12 of the 18 patients with lone IPF died in 2.66 +/- 1.18 years from the onset of respiratory symptoms, while none of the dSSc-IPF patients had died 5.6 +/- 4.25 years from the first ever appearance of respiratory involvement (p < 0.001). In conclusion, although the two groups of patients were not at an absolutely comparable stage of their disease, a worse prognosis for patients with lone IPF seems to emerge from this study.