Clinical characteristics and survival in idiopathic pulmonary fibrosis and connective tissue disease-associated usual interstitial pneumonia.

BACKGROUND: Previous studies have reported conflicting survival rates for connective tissue disease (CTD)-associated usual interstitial pneumonia (UIP) and idiopathic pulmonary fibrosis (IPF/UIP). This study investigated the differences in the clinical characteristics and prognoses of patients diagnosed with CTD-UIP and IPF/UIP.

METHODS: A retrospective review of patients with IPF (n=88) and CTD-UIP (n=67) from January 2008 to June 2013 was completed. We compared the demographics and clinical characteristics between the two groups. Survival rates were compared using a log-rank and Cox proportional hazard regression analysis.

RESULTS: Undifferentiated-CTD (UCTD) accounted for 33% of the established CTD-UIP cases. No significant differences were identified in the demographic characteristics or physiological parameters between the UCTD and CTD patients (all P>0.05). However, the CTD-UIP patients were more likely to be young, female, and nonsmokers compared with the IPF/UIP group (all P<0.01). There was no difference in survival between the IPF/UIP and CTD-UIP patients [hazard ratio (HR), 1.74; 95% confidence interval (CI), 0.86-3.50; P=0.113]. However, the removal of the UCTD patients from the CTD group revealed that IPF/UIP was associated with a 2.47-fold increased risk of mortality compared with CTD-UIP (HR, 2.47; 95% CI, 1.01-6.09; P=0.049).

CONCLUSIONS: Our findings indicate that the survival of CTD-UIP patients was similar compared with that of IPF/UIP patients. However, it appears that UCTD influences the survival rate of CTD-UIP patients.