A Retrospective Study of Prognostic Factors in Patients with Interstitial Pneumonia Receiving Long-Term Oxygen Therapy

Purpose

We retrospectively analyzed patients with clinically diagnosed interstitial pneumonia to investigate the factors which contribute to the difference in prognosis from the initiation of long-term oxygen therapy (LTOT) among subtypes.

Methods

Seventy-six patients with clinically diagnosed idiopathic interstitial pneumonia (IIP; n = 49) or interstitial pneumonia associated with collagen vascular disease (CVD-IP; n = 27) in whom LTOT was initiated in our facility from January 1999 to December 2012 were analyzed.

Results

Patients with CVD-IP had significantly longer survival time from the initiation of LTOT than those with IIP with the median survival of 51.7 months versus 18.8 months, respectively. The 1-year survival rate was 92.4 % for patients with CVD-IP versus 76.5 % for those with IIP, and 2-year survival was 88.6 versus 36.0 %, respectively. The patterns classified with high-resolution computed tomography (HRCT) were not associated with prognosis. The association between pulmonary hypertension and prognosis was unclear. In results of the multivariate Cox analysis which included factors demonstrating p < 0.1 in the univariate Cox analysis, male gender, low body mass index, and the absence of collagen vascular disease (CVD) were significantly associated with poor prognosis.

Conclusions

After the initiation of LTOT, patients with IIP had poor prognosis regardless of the patterns classified with HRCT, while those with CVD-IP survived longer. Male gender, low body mass index, and the absence of CVD were the independent negative prognostic factors in patients with interstitial pneumonia receiving LTOT.