iTTP cases, related complications rise in Germany, study finds
2011-2021 trend seen even as doctors turn to advanced treatments
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Cases of immune-mediated thrombotic thrombocytopenic purpura (iTTP) rose in Germany from 2011 to 2021, with patients also experiencing more severe complications despite advances in treatment, a nationwide study found.
Researchers found that while death rates remained stable over the 11 years, complications such as multiple-organ failure and the need for intensive care became more common. Men were more likely than women to experience severe disease, although the condition occurred more frequently in women.
“These findings warrant further research to optimize acute management and understand long-term outcomes,” the researchers wrote.
The study, “Epidemiology, therapy, and outcome of immune-mediated thrombotic thrombocytopenic purpura at population level in Germany,” was published in Research and Practice in Thrombosis and Heamostasis. It was partially funded by Sanofi, which markets Cablivi (caplacizumab), an approved therapy for iTTP.
iTTP, also known as acquired TTP, occurs when antibodies mistakenly attack ADAMTS13, an enzyme that normally helps prevent unnecessary blood clotting. When ADAMTS13 is severely reduced or dysfunctional, clots form in small blood vessels throughout the body, restricting blood flow and potentially causing organ damage.
Treatment advances
Once linked to high mortality, iTTP outcomes began to improve in the 1980s, when the standard treatment became plasma exchange (PEX), a procedure that removes disease-causing antibodies from the blood and restores functional ADAMTS13, in combination with corticosteroids. In more recent years, iTTP treatments such as rituximab, which reduces the production of harmful antibodies, and Cablivi, which helps prevent blood clots from forming, have further improved disease management.
Despite these advances, there is still “no comprehensive overview of the epidemiology, treatment behaviour, and outcomes of iTTP episodes at the population level,” the researchers wrote. Key questions, including how often patients are treated outside specialized centers and whether the disease course differs between men and women, remain, they said.
The team used a nationwide database to analyze data from all hospital-treated cases of iTTP from January 2011 to December 2021. The aim was to examine trends in disease occurrence, treatment, and outcomes.
They identified 2,771 acute iTTP episodes across Germany. The number of people treated in hospitals for the condition increased over time, rising from 2.36 cases per million people to 3.48 cases per million people over the 11-year period.
Despite this increase, the mean age of patients (50) remained stable, as did most coexisting health conditions.
Cases increased for both sexes, but the condition was more common in women, occurring about 1.4 times more often than in men. New cases in women occurred most frequently at ages 30-34, while for men, cases were more common at ages 60-64.
The researchers said the pattern may reflect a higher susceptibility to autoimmune diseases in women and possible hormonal influences during pregnancy, which may help explain the higher number of cases during childbearing years.
While the median length of hospital stay (17 days) and the proportion of patients who died during hospitalization (12.8%) remained stable, severe complications became more common over time — a trend the researchers noted was not explained by changes in the patient population, as age and other health conditions remained stable.
For example, the proportion of patients requiring intensive care rose from 44% to 51%, while those requiring breathing support increased from 14% to 22%. Cases of multiorgan failure also increased, from 23% to 42% over the study period.
Men were more likely than women to experience severe complications, including kidney failure requiring dialysis (a treatment that replaces kidney function), as well as the need for breathing support and multiple-organ failure. The more severe disease course observed in men is likely related to their older age, a known risk factor for worse outcomes in iTTP, the researchers said.
Treatment approaches also changed over time. The number of PEX sessions decreased from 12 in 2011 to six in 2021, while use of the immunosuppressive therapy rituximab increased from 24% of patients to 40%.
“This could be an expression of a changed understanding of the treatment of iTTP, in which the importance of specific immunosuppressive therapies is increasingly coming to the fore and PEX is being used with increasing caution,” the researchers wrote.
Data on the use of the targeted therapy Cablivi were available for 2020 and 2021. During this period, 34.7% of patients received treatment, with higher use among women than among men.
About half of all patients (55.4%) were treated at university hospitals. While outcomes were largely similar between university and non-university hospitals, patients treated at university hospitals were more likely to receive rituximab and undergo more PEX sessions, and have longer hospital stays.
“We report here for the first time epidemiologic data at the population level on iTTP over a decade and have found that the incidence [new cases] of diagnosed acute episodes is increasing,” the researchers concluded. “Whether new treatment options will significantly change the treatment and outcomes of iTTP in the future remains to be determined.”
