Antibody levels may help reflect quality of life in people with scleroderma
Study links antibody levels with pain, physical limits, and disease burden
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Lower blood levels of immunoglobulin G (IgG), an antibody measured through routine blood tests, were linked to poorer health-related quality of life in people with systemic sclerosis (SSc), including greater pain, reduced physical function, and higher overall disease burden, a study reports.
These findings suggest that blood IgG levels could serve as a “reliable biomarker of patient-perceived disease burden,” the researchers wrote, an area where reliable measures have long been lacking.
The study, “Lower total serum Immunoglobulin G is associated with impaired patient-reported health-related quality of life in systemic sclerosis: a prospective cross-sectional study,” was published in Rheumatology International.
Understanding scleroderma and its impact on daily life
SSc, also known as scleroderma, is an autoimmune disease in which the immune system produces autoantibodies that mistakenly attack the body’s own connective tissues. This abnormal immune response leads to excess collagen buildup, a structural protein that causes the skin and internal organs to thicken, harden, and scar over time.
People with SSc often report a reduced quality of life, yet doctors still lack reliable biological markers that reflect how patients feel and function in daily life. Common inflammation markers, such as C-reactive protein and interleukin-6, have shown weak or inconsistent links to patients’ perceived disease burden.
According to the investigators, IgG has been studied in SSc, but not specifically as a marker of health-related quality of life. In other immune-related conditions, lower IgG levels have been linked to fatigue, poorer physical function, and reduced well-being, suggesting it could play a similar role in SSc.
To explore this idea, researchers in Poland conducted a study examining whether total blood IgG levels are associated with health-related quality of life in people with SSc. They analyzed relationships between IgG levels and several validated patient-reported outcome measures and assessed whether these associations differed across clinical subgroups.
The study included 64 people with SSc, most of whom were women (89%). Participants had a median age of 57.5 years and had lived with SSc for a median of 4.2 years. All participants were hospitalized at the time they completed the questionnaires.
Around a third of participants (38%) had interstitial lung disease (ILD), and 25% had digestive symptoms. ILD, a group of disorders marked by inflammation and scarring in the lungs, is a common and serious complication of SSc.
Blood IgG levels ranged from 603 to 1908 mg/dL. About three-quarters of participants (76.6%) had received at least one immunosuppressive treatment. At the time of the study, 39.1% were receiving mycophenolate mofetil, 21.9% methotrexate, and 4.7% azathioprine.
Kidney function was largely preserved. Routine urine tests showed no meaningful protein levels in urine, and blood creatinine levels were normal in nearly all participants. Elevated creatinine is a marker of kidney dysfunction.
Lower IgG levels tied to worse patient-reported outcomes
Results showed that lower IgG levels were linked to worse disease activity as reported by patients, as well as more pain, greater physical limitations, and poorer disease-related quality of life across all four validated questionnaires used in the study.
These correlations remained consistent across multiple subgroups, including people with ILD, those with skin involvement or digestive symptoms, and patients with anti-centromere autoantibodies, which are common in SSc.
In contrast, IgG levels were higher in patients with elevated levels of erythrocyte sedimentation rate, a marker of inflammation. No correlation was found between IgG levels and interleukin-6.
Further statistical analyses showed that the association between IgG levels and health-related quality of life remained significant even after adjusting for inflammation, skin thickness, and digestive involvement, “suggesting that this relationship was not fully explained by systemic [body-wide] inflammation or skin involvement,” the scientists wrote.
The relationship between IgG levels and health-related quality of life did not differ based on whether patients were receiving immunosuppressive treatment.
“Prospective studies are warranted to evaluate whether total IgG can serve as a reliable biomarker of patient-perceived disease burden and to explore its longitudinal dynamics in systemic sclerosis,” the team concluded.
