[Relationship between the prognosis of interstitial pneumonia and its comorbidities]

To investigate the relationship between the prognosis of chronic interstitial pneumonia (IP) and its comorbidities, we conducted a retrospective study for clinically and radiologically diagnosed IP. We assessed comorbidities by using the Charlson Comorbidity Index (CCI).

We classified 224 patients given clinical diagnoses of chronic IP (excluding the patients who had clear causes such as collagen disease, infection, drugs or radiation) in our institution between April 2000 and June 2010, into 2 groups; those with clinical diagnoses of idiopathic pulmonary fibrosis (IPF:108 cases) and those with other chronic IP but without honeycomb lung (116 cases); and analyzed their backgrounds and comorbidities. We also classified them into survival and non-survival groups to assess their prognostic factors.

Although the smoking status of patients with clinically diagnosed IPF was higher, and SpO2 was lower than those with other chronic IP without honeycomb lung, the mean age, comorbidities and CCI did not differ between them. The 5-year overall survival of the clinically-diagnosed IPF group was lower than that of the other chronic IP without honeycomb lung group (50.8% vs. 76.3%, p<0.01). In cases of other chronic IP without honeycomb lung, the CCI of non-survival cases was higher than that of survival cases (4.05 vs. 2.47, p<0.01), although patient backgrounds did not differ between survival and non-survival cases in those with clinically diagnosed IPF (CCI : 2.32 vs. 2.98, p = 0.70).

Our analysis revealed the possibility that comorbidities and CCI were prognostic factors in other chronic IP cases without honeycomb lung, although the prognosis of IPF was not affected by their comorbidity.