Worse prognosis for AAV patients with pulmonary renal syndrome
Serious lung, kidney condition linked to higher risk of severe complications
Having pulmonary renal syndrome (PRS), a potentially life-threatening condition marked by lung and kidney problems, is associated with a higher risk of severe complications in people with ANCA-associated vasculitis (AAV), a new study reports.
After accounting for starting differences in kidney function, AAV patients with PRS had a six times greater chance of serious complications than those without the condition. PRS also corresponded to poorer outcomes than kidney disease alone, suggesting the interaction with lung problems may aggravate risks, according to the researchers.
“Our results suggest that the prognostic assessment of AAV could include PRS as a distinct entity at particular risk,” the team wrote.
Still, the researchers noted that “larger studies with longer follow-up periods are needed to determine the place of PRS in prognostic scores” when caring for individuals with AAV.
The study, “Prognostic impact of pulmonary renal syndrome in ANCA-associated vasculitis: A retrospective multicentre study,” was published in English and French in the journal La Revue de Médecine Interne by a team of researchers in France.
AAV is a group of rare diseases in which the immune system mistakenly attacks small blood vessels. Most cases are associated with self-reactive antibodies, called ANCAs, that typically target either the PR3 or the MPO proteins.
Depending on the affected organs and tissues, individuals with AAV can develop a wide variety of symptoms. Among the most common are symptoms of kidney and lung damage.
Pulmonary renal syndrome is combo of kidney, lung conditions
A typical feature of kidney involvement in AAV is rapidly progressive glomerulonephritis, or RPGN, a condition marked by severe inflammation of the kidney’s filtering units. Meanwhile, one of the most severe lung complications that can arise in AAV is diffuse alveolar hemorrhage, known as DAH, which is widespread bleeding in the lung’s air sacs.
The combination of RPGN and DAH is called pulmonary renal syndrome, or PRS for short.
“Although the majority of patients with RPGN do not have DAH, the majority of those with DAH also have RPGN, the latter being present in 70% to 97% of DAH cases,” the researchers wrote.
Techniques for estimating the prognosis, or likely disease course, of a person with AAV often take measurements of kidney function into consideration. However, according to the team, it is less common for clinicians to include DAH or PRS as a risk factor.
“Advances in the therapeutic management of AAV have improved the prognosis of AAVs, but few studies have been conducted to describe the incidence of serious complications in patients with PRS in the recent therapeutic era,” the scientists wrote.
To learn more, a research team from the Center Hospitalier Universitaire Grenoble Alpes retrospectively reviewed the medical records of 99 people diagnosed with AAV at three French medical centers between 2017 and 2020. The patients’ average age at diagnosis was 69.7, and they were nearly evenly split by sex. Among them, 15 met criteria for PRS, 38 had isolated RPGN, and five had isolated DAH.
There were some differences between the PRS and non-PRS groups at the start of the study, the researchers noted. A significantly greater proportion of those without PRS had anti-MPO ANCAs relative to those with PRS (75% vs. 53%).
Also, the PRS group was significantly more likely to have heart damage (20% vs. 4%) and showed generally worse kidney function.
PRS ‘should be considered’ in giving a prognosis, researchers say
For the year following diagnosis, the researchers looked at the incidence of three serious complications: the start of dialysis, a treatment strategy that filters blood when the kidneys are unable to do so; admission to the intensive care unit (ICU); and death.
A total of 32 people had at least one severe complication. A significantly greater proportion of people with PRS (80%) experienced a severe complication compared with those without PRS (24%) and those with isolated RPGN (40%). ICU admissions in the PRS group all occurred in the month following diagnosis.
Initial statistical analyses showed that PRS was significantly associated with a 26 times greater chance of experiencing severe complications relative to no PRS. People with isolated RPGN also had a sixfold higher chance of severe complications relative to those without RPGN nor DAH.
Analyses adjusted for kidney function at diagnosis still showed a sixfold higher risk of severe complications for people with PRS. However, the isolated RPGN and isolated DAH groups had similar risk levels as patients without those conditions.
Among the 87 people who were alive one year after diagnosis, kidney function metrics were still significantly worse in the PRS group than in the non-PRS group, the data showed.
[These findings point to PRS as] a strong predictor of severe complications, independently of the severity of initial [kidney] damage.
Although individuals with PRS tended to have poorer kidney function than those with isolated RPGN, the differences were not statistically significant, according to the researchers. The findings “could be explained by a lack of statistical power or could reflect a possible partial improvement in [kidney] function after the initial phase in patients with PRS,” the team wrote.
These findings point to PRS as “a strong predictor of severe complications, independently of the severity of initial [kidney] damage,” the researchers wrote, adding that the condition “should be considered when estimating prognosis, rather than considering only the [kidney] involvement of this syndrome for prognostic purposes.”
The team emphasized, however, the need for larger studies to confirm these findings and determine the best way to include PRS in prognostic scores.
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