Chest CT confirms pneumonia in patients with RA-ILD

Chest CT in patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) can accurately identify the histopathologic usual interstitial pneumonia (UIP) pattern, according to a study published in the February issue of Radiology.

Detection of one of the primary histopathologic patterns associated with RA-ILD, UIP, may improve treatment, disease progression, and prognosis in the clinical realm.

“Those with UIP pattern tend to be older, are more likely to be men, and seem to be less responsive to conventional treatment compared with RA-ILD patients with non-UIP pattern,” wrote the study’s lead author, Deborah Assayag, MD, of the University of California-San Francisco, and colleagues. “In addition, the UIP pattern in RA-ILD is associated with significantly shortened survival compared with that in those without the UIP pattern.”

Chest CT has been previously proven to aid in accurate prediction of histopathologic UIP pattern in some patients with idiopathic pulmonary fibrosis. Assayag and colleagues designed their study to determine the accuracy of CT in identifying the histopathologic UIP pattern in patients with RA-ILD.

CT images from 69 patients with RA and biopsy-proven ILD were analyzed in the study and independently reviewed by two thoracic radiologists. Using published criteria, the radiologists categorized CT patterns as definite UIP, possible UIP, or inconsistent with UIP. Biopsy results were reviewed by an experienced lung pathologist. Lastly, the sensitivity and specificity of definite CT UIP pattern to histopathologic UIP pattern were established.

Results indicated that histopathologic UIP pattern was found in 61 percent of the patients. Male sex was the only clinical variable associated with histopathologic UIP pattern. Twenty patients had a definite UIP pattern on CT scans. The specificity of CT UIP pattern was 96 percent with a negative predictive value of 53 percent, while the sensitivity was 45 percent with a positive predictive value of 95 percent. 

Though the study may have been limited by obtaining the CT images from three different tertiary centers and the potential for spectrum bias, the findings were still promising, Assayag and colleagues wrote.

“Given the physiologic impairment seen in this patient population and the risks associated with surgical lung biopsy, the accurate identification of the UIP pattern in patients with RA-ILD by using noninvasive diagnostic tests such as CT is important,” concluded the study’s authors.