Treating kidney damage of benefit for AAV patients up to age 80: Study
Higher mortality rate and dependence on dialysis seen in very elderly
ANCA-associated vasculitis (AAV) with kidney involvement is the most common cause of kidney disease among elderly people, but most older patients appear to benefit from appropriate therapy as well as younger AAV patients with kidney damage.
That’s according to a study in Germany that found no significant differences in kidney outcomes over two years of follow-up between patients ages 65 to 79 and those of younger ages. However, elderly patients — those age 80 or older — showed particularly poor kidney and survival outcomes.
These findings also may explain why the researchers found that the ability of routine assessment models to predict kidney and survival outcomes differed with age.
They highlight that “generally applied prognostication models might neglect vulnerable subgroups, as shown here in very elderly patients,” the researchers wrote in the study “General prognostic models may neglect vulnerable subgroups in ANCA-associated vasculitis,” published in the Journal of Nephrology.
Kidneys are often affected in ANCA-associated vasculitis patients
An autoimmune disease, AAV is marked by inflammation and injury to small blood vessels. The kidneys are commonly affected, with patients often developing glomerulonephritis, or inflammation in the kidneys’ filtering units (glomeruli).
AAV is more frequent among people between 65 and 74 years old. While guidelines exist for treating AAV in elderly patients, few studies have reported on treatment and outcomes among those ages 65 and older, or compared them with younger patients.
Researchers at University Hospital Marburg, in Germany, retrospectively analyzed demographic and clinical data from 774 adults who underwent a kidney biopsy at their hospital from 2001 to 2017 and then were followed for up to two years.
A total of 268 patients were age 65 or older, and 54 of them (20%) had AAV, indicating that this autoimmune condition was the most common cause of kidney disease in this older patient group. This group’s median age at AAV diagnosis was 75, and 52% were male.
In addition, 28 patients younger than age 65 (median age, 51.6; 54% men) were found to have AAV.
When comparing AAV patients in these two age groups, researchers found that older patients had significantly more co-existing health conditions and significantly poorer kidney function, as assessed with the estimated glomerular filtration rate (eGFR).
“There was no difference in the percentage of patients receiving standard vs. alternative induction and maintenance therapy in the respective age groups,” the team wrote.
Kidney replacement therapy, such as dialysis, was used more frequently in the older patient group (41%) than in the younger group (25%), but this difference failed to reach statistical significance.
Over follow-up, deaths were reported in 10 elderly patients (18.5%) and one younger patient (3.6%); their median age at death was 79. Five patients (45%), including four who were elderly, died within one month of being diagnosed; nearly three-quarters of them (73%) were on kidney replacement therapy, which is indicated for people with severe kidney injury or failure.
Among kidney replacement therapy patients who were alive by the end of the follow-up, 38% progressed to kidney failure. No significant differences between older and younger patients were seen in replacement therapy-associated kidney recovery rates (41% vs. 57%) and in kidney function based on eGFR in the first and second year.
No patient with sufficient kidney function at diagnosis progressed to kidney failure.
Difference in ability of predictive models seen with older vs. younger patients
“Our data suggest that elderly as well as younger patients can effectively avoid progression to [kidney failure] by guideline-directed therapy,” the researchers wrote.
However, outcomes were more severe in patients ages 80 or older relative to those younger than age 80. These included a significantly higher mortality rate (70% vs. 6%) and an inability to recover from a dependency on dialysis, with all very elderly dialysis patients dying within the two follow-up years.
Statistical analyses accounting for potential influencing factors showed that the need for kidney replacement therapy and older age were independently associated with two-year mortality in all patients and in the elderly group.
However, the statistical model’s ability to predict mortality was not as good in the whole patient group as in the elderly (sensitivity of 46% vs. 70%). A test’s sensitivity is the ability to correctly identify those with a particular outcome.
Clinical and/or tissue measures were able to predict eGFR-based kidney function after two years in younger patients, but they “failed to accurately predict [kidney] outcome in the elderly,” the researchers wrote.
Study findings show “that [kidney] and survival model accuracy differs dependent on age,” the team wrote, as “routinely assessed parameters do not allow for reasonable prognosis in the elderly.”
Accordingly, “clinically intuitive ‘unfavorable predictors’ should not inform decision making,” they suggested, adding “there might be no one-size-fits-all approach to [kidney] or survival modelling.”
Further research is “needed to inform therapy indication and intensity in very elderly patients with AAV who carry the highest mortality and morbidity burden,” the researchers concluded.