Objective To investigate whether or not the newly revised classification of the severity of idiopathic interstitial pneumonia (IIP) is appropriate with respect to quality of life (QOL).
Methods The association between the subscale of Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and pulmonary function or serum marker was analyzed using Pearson′s correlation coefficient. The association between the subscale of SF-36 and the previous or newly revised classification of the severity of IIP was analyzed using Spearman′s rank correlation test.
Patients Forty patients with idiopathic pulmonary fibrosis (IPF) were enrolled.
Results The mean deviation value scores for 7 items, excluding bodily pain (BP) in SF-36 were below the national reference values. % vital capacity (VC) was correlated with the 7 items excluding BP. However, neither serum LDH nor KL-6 values were correlated with any item in SF-36. According to the new or previous classification of the severity, severity was correlated with physical function, limitation of role functioning related physical problems and general health (GH); the correlation coefficient with the new one was slightly higher than the previous one. Based on these results, we established a unique draft on the classification of the severity. %VC <70% was added as an item for the newly revised classification in our draft. In our draft, there was rank correlation between the 7 items, excluding BP, in SF-36 and severity.
Conclusion With respect to QOL, the newly revised classification of the severity of IIP was not satisfactory, but the hypoxemia during exercise in patients with resting PaO₂ >80 Torr and reduction of VC were found to be important factors.