Broader criteria of undifferentiated connective tissue disease in idiopathic interstitial pneumonias

Abstract

Background: Kinder et al. proposed a broader definition of undifferentiated connective tissue disease (UCTD) and reported that the entity of nonspecific interstitial pneumonia (NSIP) is a lung manifestation of this more broadly defined UCTD. However, a retrospective study did not support their findings and its clinical significance remains unclear.

Methods: We prospectively evaluated the significance of this broadly defined UCTD in idiopathic interstitial pneumonias (IIPs) in consecutive patients with surgical lung biopsy. Patients were evaluated with a symptoms check list and underwent comprehensive serologic testing as screening for UCTD. Clinical characteristics, high-resolution CT images, lung biopsy specimens, serial FVC change, and survival were analyzed.

Results: Among 76 patients with IIPs, 24 patients (32%) fulfilled the UCTD criteria. Diagnosis of 24 patients with UCTD was usual interstitial pneumonia in 12 (50%), NSIP in 7 (29%), and unclassifiable interstitial lung disease (ILD) in 5 (21%). The diagnosis of 52 patients who did not have UCTD was idiopathic pulmonary fibrosis in 27 (52%), NSIP in 11 (21%), unclassifiable ILD in 13 (25%) and cryptogenic organizing pneumonia in 1 (2%). One-year and two-year FVC changes showed no significant difference between UCTD and non-UCTD, however, significant differences in FVC change were observed among histopathological diagnoses both in UCTD and in non-UCTD. In multivariate survival analysis, %FVC and histopathological UIP pattern were independent predictors for survival but UCTD diagnosis was not.

Conclusions: A diagnosis of UCTD was not useful in discriminating NSIP or in predicting disease progression and prognosis in our cohort of IIPs. Histopathological UIP pattern was an independent predictor for mortality irrespective of a diagnosis of UCTD.

Keywords: IIPs – idiopathic interstitial pneumonias; IPF – idiopathic pulmonary fibrosis; NSIP – nonspecific interstitial pneumonia; SLB – surgical lung biopsy; UCTD – undifferentiated connective tissue disease.