PURPOSE: Interstitial lung disease (ILD) commonly occurs in the setting of connective tissue disease (CTD). We hypothesized a diagnosis of connective tissue disease associated ILD (CT-ILD) favorably influenced survival compared to patients with idiopathic pulmonary fibrosis (IPF) or idiopathic nonspecific interstitial pneumonia (iNSIP). Furthermore, we hypothesized screening serologies for CTD and simple radiographic features predict the presence of CT-ILD.
METHODS: Patients referred for evaluation of ILD at National Jewish Health between April 2002 and November 2004 underwent a standard clinical evaluation that included serologic screening with rheumatoid factor and antinuclear antibody testing. Connective tissue diagnoses at presentation were based on American College of Rheumatology criteria or standard clinical classification schema. Consensus features from high resolution chest CT were obtained by two thoracic radiologists for each case. Survival in patients with CT-ILD was compared to patients with IPF and idiopathic NSIP. The value of serologic testing and HRCT features to predict a diagnosis of CT-ILD was assessed with logistic regression.
RESULTS: 135 patients were evaluated. 38 were diagnosed with CT-ILD, 52 with IPF, 18 with iNSIP, and 26 with another etiology. Survival among patients with CT-ILD was improved compared to patients with IPF (log rank p<0.001) but not compared to iNSIP. The presence of a high titer ANA or RF was strongly associated with a diagnosis of CT-ILD (ANA >= 1:320, OR 5.1; 95%CI 1.4-17.7); p=0.012; RF > 60, OR 15.4; 95%CI 3.6-65.6; p<0.001). The presence of a pericardial effusion or thickening (OR 5.8; 95%CI 1.8-6.2; p=0.003) or esophageal dilatation (OR 2.2; 95%CI 0.8-11.1; p=0.126) independently predicted CT-ILD, while the presence of honeycombing reduced the likelihood of CT-ILD (OR 0.07; 95%CI 0.03-0.16; p<0.001).
CONCLUSIONS: A diagnosis of CT-ILD was associated with improved survival. Clinical factors easily accessed by a general pulmonologist independently predicted CT-ILD.
CLINICAL IMPLICATIONS: Screening features obtained from simple lab tests and a chest CT may predict a diagnosis of CT-ILD and improved survival compared to IPF.
DISCLOSURE: The following authors have nothing to disclose: Tristan Huie, Harold Collard, Joshua Solomon, Hakan Sahin, Alyn Woods, Brent Kinder, Douglas Curran-Everett, David Lynch, Aryeh Fischer, Kevin Brown
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