Lab Tests at AAV Diagnosis May Carry Long-term Predictive Value

Patricia Inacio, PhD avatar

by Patricia Inacio, PhD |

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A combination of lab tests commonly used to diagnose ANCA-associated vasculitis (AAV) may be able to accurately predict the long-term prognosis of patients and maybe select those needing more aggressive treatment, according to a 15-year study in China.

The study, “Long-Term Prognostic Factors in Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A 15-Year Multicenter Retrospective Study,” was published in Frontiers in Immunology.

AAV is a group of diseases wherein certain autoantibodies, called anti-neutrophil cytoplasmic antibodies (ANCAs), target proteins at the surface of immune cells, leading to inflammation and damage in small blood vessels.

While immunosuppressive treatments have improved the prognosis of people with AAV of late, it’s estimated that only about 75% of patients survive five years past their diagnosis. The long-term prognosis of AAV patients in China remains poorly understood, however.

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Researchers in China reviewed clinical and laboratory data from 407 patients diagnosed across 16 centers in the country between August 2005 and December 2020.

Participants included 209 women and 198 men, with a median age of 60. Most (91.4%) had either microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA). The others had other, less common forms of AAV.

Over a median follow-up time of 1,266 days (about 3.5 years), 153 patients (37.6%) died. The median survival of this group of patients was 2,290 days, or 6.3 years.

After one year, 84.2% of patients were alive. That percentage dropped to 76.3% at three years, 57.2% at five years, and 32.4% at 10 years.

The researchers looked for clinical measures that helped predict three- and five-year survival rates in these patients. These included measures such as neutrophil-to-lymphocyte ratio (NLR) and the C-reactive protein (CRP), which are used as inflammation biomarkers.

Several factors, such as age, disease type, and presence and type of ANCA antibodies, were all predictors of long-term survival, statistical analyses revealed. Other prognostic factors included the presence of antinuclear antibodies (ANA), the glomerular filtration rate (GFR, a measure of  kidney function), lymphocyte (white blood cell) counts, as well as NLR and CRP levels.

Having detected individual associations between these factors and prognosis, the team then used all these parameters together to generate a nomogram, a commonly used tool to estimate prognosis.

This novel tool “had good accuracy and applicability in the prediction of 3-year and 5-year survival rates for AAV patients,” the researchers wrote, noting that its accuracy in predicting survival was about 72%.

“Our study revealed that laboratory examinations at diagnosis had great significance for predicting long-term prognosis in AAV patients,” they concluded.