Researchers have developed a specific index for ANCA-associated vasculitis (AAV) that uses laboratory results at the time of diagnosis to help assess disease activity and predict death by any cause.
The index could supplement currently-used indexes such as the Birmingham Vasculitis Activity Score (BVAS) to guide treatment course at diagnosis, the investigators said.
The study, “Multivariable index for assessing the activity and predicting all‐cause mortality in antineutrophil cytoplasmic antibody‐associated vasculitis,” was published in the Journal of Clinical Laboratory Analysis.
Early diagnosis and treatment is crucial in AAV, because not using aggressive therapies in patients with severe disease may lead to irreversible organ damage and affect quality of life. The appropriate treatment should consider the stage and severity of disease.
Doctors use different indexes, such as BVAS and the Five‐factor score, to assess severity, activity, and prognosis in AAV patients. However, none of these tools can estimate AAV activity at diagnosis and predict death from all causes, so new specific indexes are needed.
Therefore, researchers in South Korea used lab results of 182 AAV patients at the time of their diagnosis to determine the parameters associated with disease severity and death from any cause.
The researchers also calculated disease severity according to BVAS — 63 participants had severe AAV (BVAS of 16 or more) — and considered age, gender, and clinical symptoms.
Participants with severe AAV had more symptoms and manifestations in their internal organs than those with non-severe disease. Age and sex did not affect disease severity.
Patients with severe disease had more neutrophils and platelets, higher levels of creatinine (an indicator of kidney damage), erythrocyte sedimentation rate, and C-reactive protein (both markers of inflammation) and less white blood cell counts, hemoglobin, and serum albumin than their non-severe counterparts.
After applying a statistical model, the researchers found that creatinine levels of 0.9 mg/dL or above significantly predicted severe disease. A white blood cell count of 1430.0/mm3 or lower and hemoglobin levels of 10.8 g/dL or lower also served as predictors.
The investigators constructed a new index called multivariable index for AAV (MVIA) based on the three predictors. The values of the index range between 0 and 2.1, with higher scores indicating more severe disease.
The MVIA threshold for severe AAV was set as 1.35. Participants with MVIAs over 1.35 survived less than those with lower MVIAs. Higher MVIA scores were associated with higher BVAS at diagnosis, but MVIA classified more participants as having severe AAV compared with BVAS — 79 vs. 63.
“Since MVIA consists of only laboratory variables, which are routinely measured at every visit, it is more convenient to evaluate the severity of AAV. And furthermore, if we develop an automatic calculator of MVIA, severe AAV based on BVAS may be rapidly and promptly assessed,” the researchers wrote.
“Calculating MVIA, along with BVAS might ensure that patients with severe disease and poor prognosis receive more severe induction therapies at the time of diagnosis,” they said.
Since the researchers considered MVIA scores only at the time of diagnosis, further studies should investigate if the index can calculate the rate of disease progression during follow up, and once the patients start treatment, the study stated.
“We have first developed an AAV‐specific index for assessing the cross‐sectional [at a given time] activity and severity and predicting all‐cause mortality in patients with AAV,” the researchers said.