Routine blood test may help flag lung disease risk in diffuse SSc, study says
A high ESR reading can tell doctors to quickly send a patient for a chest scan
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A simple, widely available blood test may help flag people with diffuse systemic sclerosis (SSc) who are more likely to have interstitial lung disease (ILD), a serious complication marked by inflammation and scarring in the lungs, a study in Turkey found.
Patients with ILD had a higher erythrocyte sedimentation rate (ESR), a common blood test that measures how quickly red blood cells settle to the bottom of a test tube over one hour. Red blood cells tend to settle faster when inflammation is present, so a higher ESR is generally considered a sign of greater inflammation.
Because ESR is inexpensive and routinely available, the findings suggest it could offer doctors a simple way of flagging people at higher risk of ILD who should be prioritized for lung imaging, particularly in settings where access to specialized testing is limited.
“Our results show that checking the ESR is an easy and cheap way to spot patients who are at a higher risk [of ILD],” researchers wrote. “A high ESR reading can tell doctors to quickly send the patient for a chest scan.”
The study, “Diagnostic utility of erythrocyte sedimentation rate and anti-Scl-70 positivity for interstitial lung disease in diffuse systemic sclerosis,” was published in Therapeutic Advances in Respiratory Disease.
Interstitial lung disease a major cause of death in SSc patients
SSc, also known as scleroderma, is an autoimmune disease in which the immune system mistakenly attacks healthy tissues. This leads to inflammation and the buildup of scar tissue, or fibrosis, in the skin and internal organs. In diffuse scleroderma, a subtype of SSc, skin fibrosis is more widespread, and internal organs, including the lungs, are more likely to be affected than in limited scleroderma.
ILD develops when inflammation and fibrosis affect the tissue in and around the lungs’ tiny air sacs, making it harder for the lungs to work properly. It is a major cause of death in people with SSc, making early detection particularly important.
High-resolution computed tomography (HRCT), a type of detailed chest scan, is considered the gold standard for evaluating ILD. Current guidelines recommend HRCT screening for all people with SSc at diagnosis, but the scans expose people to radiation, can be costly, and may not be readily accessible in all healthcare settings.
These factors led researchers in Turkey to investigate whether simple measures already available from routine blood tests could help identify people with diffuse scleroderma who are more likely to have ILD and may warrant particular attention for lung imaging.
Anti-Scl-70 antibodies also showed an association with lung disease
The team retrospectively analyzed data from 117 adults with diffuse scleroderma who had undergone HRCT at Hatay Mustafa Kemal University between 2018 and 2025. Participants had a mean age of 49 years, and 106 (90.6%) were women. HRCT detected ILD in 62 participants (53%).
The researchers then compared routine blood measures and several inflammation-related markers between participants with and without ILD.
ESR emerged as the clearest inflammation-related marker significantly associated with lung involvement. Median ESR was 20 mm/hour in participants with ILD versus 12 mm/hour in those without it.
The researchers then identified an ESR higher than 23.5 mm/hour as the best cutoff for distinguishing between participants with and without ILD. At that threshold, ESR had 90.9% specificity, meaning about 91% of participants without ILD were correctly identified as falling below the cutoff.
However, its sensitivity was only 43.5%, meaning the cutoff identified fewer than half of the participants who actually had ILD. A lower ESR therefore cannot be used to rule out ILD.
Anti-Scl-70 antibodies, a type of self-reactive antibody commonly associated with SSc and an increased risk of lung involvement, also showed a significant association. Half of the people with ILD tested positive for the self-reactive antibody, compared with 27.3% of those without ILD.
ESR appears to be a potentially useful, independent indicator of interstitial lung disease in patients with [diffuse scleroderma].
After accounting for factors that could influence the results, including age, sex, and immunosuppressive treatment, both higher ESR and anti-Scl-70 positivity remained independently associated with ILD.
In a statistical analysis accounting for immunosuppressive treatment, each 1 mm/hour increase in ESR was associated with 6.7% higher odds of ILD. The association was nearly identical — 6.8% higher odds — in a separate analysis that instead accounted for whether participants had been newly diagnosed. Anti-Scl-70 positivity was associated with about three times higher odds of ILD in both analyses.
“ESR appears to be a potentially useful, independent indicator of interstitial lung disease in patients with [diffuse scleroderma],” the researchers wrote. “When considered alongside Anti-Scl-70 positivity … ESR may serve as a complementary, cost-effective, and widely accessible marker for assessing ILD risk.”
ESR may also have value on its own “as a practical preliminary triage tool to assist clinicians in prioritizing high-risk patients for further radiological evaluation, particularly in clinical environments where access to specialized antibody testing or advanced imaging may be limited,” the team added.
Still, they wrote, larger, prospective studies that include lung function testing are needed to confirm the findings and determine how ESR could best be used in clinical practice.
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