Abstract

Background: The disease behavior in cases of newly diagnosed IIPs has rarely been investigated prospectively.

Methods: In JIPS registry, progression-free survival (PFS) and the percentage of cases meeting progressive fibrosing interstitial lung disease (PF-ILD) criteria were longitudinally investigated. PFS was defined as duration without any event of death, an absolute decline of forced vital capacity (FVC) =10%, onset of acute exacerbation, or a decline of >50 meters in the 6-minute walk distance. The PF-ILD criteria were defined as: 1) relative annual decline of FVC =5%, 2) FVC decline =2.5% and worsening of mMRC or CT findings, or 3) worsening of mMRC and CT findings.

Results: In 866 cases with IIPs, mean age was 70 years, and mean FVC %predicted was 80%. The most common was IPF (469 cases), followed by unclassifiable IIP. Median PFS of IPF and unclassifiable IIP were 24.2 and 24.6 months, respectively (HR = 0.91 (95%CI: 0.76–1.10), log-rank test: p = 0.345). Three-year progression-free rates for IIPs, IPF, and unclassifiable IIP were 40%, 36%, and 40%, respectively. After 1 and 2 years, 23% and 37% met the PF-ILD criteria for IIPs: 24% and 42% for IPF, and 23% and 39% for unclassifiable IIP.

Conclusions: Among newly diagnosed IIP cases, the prognosis of unclassifiable IIP was similar to that of IPF within 3 years. (NCT03041623)