High False Negative Rate in Detecting Scleroderma Lung Disease Associated With Pulmonary Function Tests

In a recent study published in the journal Arthritis & Rheumatology, entitled, “Pulmonary Function Tests: High Rate of False Negatives in the Early Detection and Screening of Scleroderma Interstitial Lung Disease,” a team of researchers from the University Hospital Zurich led by Yossra A. and Suliman, M. found that the use of pulmonary function tests (PFTs) is linked with high false negative rates for identification of scleroderma-associated interstitial lung disease (SSc-ILD).

Systemic sclerosis (SSc), or scleroderma, is a heterogeneous and complex autoimmune disease characterized by varying degrees of skin and organ fibrosis and obliterative vasculopathy. The disease results in significant morbidity and mortality, and currently available treatments are limited. Lung involvement is the leading cause of death of patients with SSc.

The team of researchers conducted a prospective study involving 102 SSc patients. All patients were evaluated using the EUSTAR recommendations so that comparisons between PFTs and high-resolution computed tomography of the chest (HRCT) could be investigated. Two proficient radiologists were blinded to evaluate the images retrieved from the scans.

Findings revealed that 63% of patients showed significant ILD on the HRCT scan, 26% had a forced vital capacity (FVC) that was less than 80%, and 53% of those studied had a reduction in one or more PFTs. The false negative rate of FVC was noted to be high, with normal FVC in 62.5 percent of patients with significant ILD on HRCT. Six percent of patients with normal FVC had severe, functionally-occult lung fibrosis; two of these patients had all PFTs within normal limits.

In comparison with ILD-free cases, the results showed that false negative cases frequently had more anti-Scl-70 antibodies and diffuse SSc, and less often had anti-centromere antibodies (ACA).

These findings indicate that HRCT scans, even when conducted by the most skilled radiologists, may lead to false negatives in detecting SSc of the lung. “The derived evidence-based data reveal a high risk of missing the detection of significant SSc-ILD when relying solely on PFTs,” the authors wrote according to a recent news release. “Particularly, additional imaging investigations should be considered in ACA negative patients with normal FVC for the early detection of SSc-ILD.”