Tracking organ damage after GPA diagnosis predicts relapse risk
Tracking damage in first year proves better predictor than single measure
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Tracking organ damage over the first year after a diagnosis of granulomatosis with polyangiitis (GPA), the most common type of ANCA-associated vasculitis (AAV), predicts relapse risk more reliably than a single damage measurement early in the disease course, a study found.
GPA patients whose cumulative damage score reached a certain threshold within the first year had about 6.5 times the risk of relapse. A one-time early measurement lost its predictive value once potential influencing factors were taken into account.
“Early damage accrual — rather than the status at a single point of measurement — better reflects the disease burden that predisposes to relapse in GPA,” the researchers wrote. “Incorporating early cumulative damage assessment into routine clinical evaluation may improve relapse risk stratification and help identify patients who require more vigilant follow-up and individualised therapeutic strategies.”
The findings were described in the study, “Association of the first-year cumulative vascular damage index with relapse risk in granulomatosis with polyangiitis: a retrospective cohort analysis,” published in Clinical Rheumatology by a team of researchers in South Korea.
GPA is a type of AAV, a group of autoimmune diseases that affect the small blood vessels, causing inflammation and, over time, permanent organ damage. GPA is marked by granulomas, or clumps of immune cells, in tissues, and disease symptoms frequently involve the lungs, upper respiratory tract, and kidneys.
Watching for relapse
While immunosuppressive AAV treatments have improved survival in people with GPA, relapse remains common, with as many as half of patients experiencing a relapse within five years.
“Considering the irreversible organ damage and increased mortality that is associated with relapse, early identification of patients at high risk of relapse and close monitoring are essential for optimising long-term outcomes and individualising treatment strategies,” the researchers wrote.
They set out to identify early on which patients are most likely to relapse. They used the Vascular Damage Index (VDI), a validated AAV severity tool that includes 64 possible items of permanent damage across 11 organ systems.
Most previous studies had looked at a single VDI score taken at one point in time, such as three months or two years after AAV diagnosis. The researchers calculated a first-year cumulative VDI, which adds up damage scores measured repeatedly across the first year.
The team retrospectively analyzed data from 39 people (median age 60, 43.6% men) who were diagnosed with GPA at a single South Korean hospital. The most frequently involved organs were the lungs (76.9%), followed by the ear, nose, and throat (69.2%) and the kidneys (38.5%).
Over a median follow-up of 40.6 months (nearly 3.5 years), 18 patients (46.2%) experienced relapses. Those who relapsed had significantly higher median VDI scores than those who did not, both for the earliest single VDI assessment (4 vs. 2) and for the first-year cumulative VDI (32.3 vs. 14.8).
When researchers tested how well each measure predicted relapse, the first-year cumulative VDI generated an area under the curve, or AUC, of 0.817, with an optimal cut-off VDI value of 23.6. AUC values range from 0 to 1, with higher values indicating better predictive potential.
By comparison, the AUC of the earliest VDI was 0.734. However, the difference between the two AUCs failed to reach statistical significance, meaning it could have occurred by chance.
An unadjusted statistical analysis showed that the earliest VDI, first-year cumulative VDI of at least 23.6, and levels of two blood proteins (hemoglobin and albumin) were each significantly associated with the risk of relapse.
Statistical analyses adjusted for these potential influencing factors demonstrated that a first-year cumulative VDI of 23.6 or higher remained a predictor of relapse, being linked to a 6.5 times higher risk. In contrast, the single-timepoint earliest VDI could no longer predict relapse risk.
Further tests confirmed that patients with a first-year cumulative VDI of at least 23.6 had a significantly shorter relapse-free survival relative to those with a lower cumulative VDI value.
The team noted that VDI scores typically increase with age at diagnosis and are generally lower among those treated with rituximab, an approved GPA treatment sold as Rituxan and others (with biosimilars available). Still, neither age nor rituximab use showed a significant association with relapse risk in the unadjusted analysis.
The researchers said that when they included these factors in an adjusted analysis, the first-year cumulative VDI remained significantly associated with a 6.9-fold higher relapse risk, “and thus reinforced the validity of our findings.”
“The first-year cumulative VDI could be useful as an independent predictor of relapse in patients with GPA,” underscoring “the prognostic importance of early damage accumulation in determining long-term disease control,” they wrote. They added that larger, multicenter studies involving more diverse populations and following patients over time are needed to confirm the findings.
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