ANCA Patients With Kidney Inflammation at High Risk for VTE Blood Clots

People with kidney inflammation due to ANCA-associated vasculitis (AAV) have a high incidence of venous thromboembolism or VTE, a potentially dangerous type of blood clot, a new study shows.

However, treatment with statins — cholesterol-lowering medications — may significantly reduce patients’ VTE risk, researchers say.

The study, “Incidence and Risk Factors of Venous Thromboembolic Events in Patients with ANCA-Glomerulonephritis: A Cohort Study from the Maine-Anjou Registry,” was published in the Journal of Clinical Medicine.

VTE occurs when a blood clot forms in a deep vein — typically a vein in the legs, though sometimes they form in the arms. Without treatment, VTE can cause dangerous restrictions in blood flow and oxygen delivery in the body.

Multiple autoimmune diseases, including AAV, have previously been linked with an increased risk of blood clots. Additionally, kidney involvement in AAV patients is thought to increase VTE risk.

However, no previous study had specifically addressed the risk factors associated with VTE for people with AAV-associated kidney disease, nor has research examined the prognosis of such patients after a VTE.

In the new study, researchers in France analyzed clinical data for 133 patients with ANCA-associated glomerulonephritis (ANCA-GN), or kidney inflammation. Their mean age was 65.1 years, and nearly two-thirds were men (63.2%).

The data were obtained from the Maine-Anjou AAV registry, which records clinical and demographic data for adults with ANCA-GN diagnosed at four hospitals in France. All of the included patients had data from at least six months of follow-up time available.

Over a median follow-up of 40.5 months (about 3.3 years), a total of 25 VTEs occurred in 23 individuals, representing 17.3% of the total group.

“In the present study, we confirm a high incidence of VTE in ANCA-GN patients,” the researchers wrote.

Most blood clots occurred soon after the ANCA-GN diagnosis: the median time between diagnosis and VTE was three months, and the estimated one-year incidence of such clots was 12.4%. Notably, significantly more people who experienced an early VTE, specifically within three months of diagnosis, developed end-stage kidney disease (ESRD) — when the kidneys no longer function properly — during follow up (66.6% vs. 22.3%).

“Interestingly, we observed that patients that experienced VTE within the first 3 months following AAV diagnosis developed more frequently ESRD,” the researchers wrote.

“Unfortunately, the low number of patients with this condition does not allow us to analyze causative factors extensively,” they said, highlighting this as an area for future study.

Using statistical models, the researchers looked for clinical and demographic factors that were identifying risk factors for VTE. In models that accounted for multiple variables at once, the only factor that was significantly associated with VTE risk was the use of statins.

Statins are a group of medications used to lower cholesterol. They also have been linked with a lower risk of heart disease and of certain blood clots. Of note, previous research has suggested that statins may lower the risk of VTEs specifically, particularly in people who are already at high risk.

In this study, individuals who were not treated with a statin were at about 4.73 times greater risk of VTE.

“Given that anti-thrombotic [anti-clotting] properties of statins may be stronger in patients at high VTE risk, we suggest that their anti-thrombotic action may be greatly enhanced in ANCA-GN patients, which could account for our results,” the researchers wrote.

“The present study identifies statin therapy as an independent risk factors of VTE in ANCA-GN patients, thus suggesting a protective role of statins and opening interesting research and therapeutic perspectives,” they added.

The study’s main limitation is its observational design. By their nature, observational studies are useful for finding statistical associations, but cannot definitively identify cause-and-effect relationships. The researchers also noted that their data was likely incomplete — for example, since people in the Maine-Anjou registry do not undergo systematic screening for VTEs, it is possible that some blood clots were not diagnosed and, therefore, not recorded in the data.

“Despite these limitations, this study is the first to analyze specifically the incidence and risk factors of VTE in a well characterized population of patients with ANCA-GN,” the researchers concluded. “These results may help identifying ANCA-GN patients with higher VTE risk and defining specific preventive strategies.”