Acquired hemophilia A high in Hong Kong; most patients older, frail
Age linked to worse prognosis, study finds
The incidence of acquired hemophilia A (AHA) was nearly twice as high in Hong Kong than in Caucasian populations previously observed, a study found. Patients in Hong Kong tended to be older and have co-existing medical conditions, with age being a significant predictor of mortality and failure to achieve disease remission.
Complications associated with the use of immunosuppressive therapies were a leading cause of death.
“This study highlights the unique epidemiological and clinical features of AHA in the local Chinese population,” Albert Sin Chun-Fung, a physician and clinical assistant professor at the University of Hong Kong and the study’s first author, said in a university press release. “These are clearly vulnerable patients who require specialised, age-appropriate care. But the reality is that diagnosis is often delayed, and hospital stays are excessively long.”
The researchers said the findings highlight a critical need to raise awareness about AHA in local communities in order to ensure prompt diagnosis and to spur research into better treatment strategies.
The study, “Characteristics and outcome of a territory-wide cohort study of patients with acquired hemophilia A in Hong Kong,” was published in the journal Thrombosis Research.
Rare condition can be life-threatening
AHA is a rare type of hemophilia in which the immune system fails to recognize factor VIII (FVIII) — an important blood clotting protein — as a healthy part of the body and launches an attack against it.
As with inherited forms of hemophilia, AHA leaves patients prone to episodes of spontaneous or excessive bleeding. In some cases, bleeds can be sudden, severe, and life-threatening.
Since AHA is rare, most of what’s known about its clinical characteristics and management come from observational studies. Most of these studies to date have been conducted in Caucasian populations. There’s a need for more research in East Asian patients, since there can be differences in clinical features between these groups, according to the Hong Kong researchers.
The researchers analyzed medical records from 165 patients diagnosed with AHA at public hospitals in the territory from January 2012 to December 2021. This could represent “the vast majority of patients with AHA in Hong Kong,” the authors wrote.
The estimated incidence of AHA was found to be 2.4 new AHA cases per million people in Hong Kong each year. That’s nearly twice as high as what has been observed in Caucasian populations, according to the authors.
There was a predominance of older people with multiple other coexisting conditions, such as a history of stroke or heart attack. The median age at diagnosis was 80.
Nearly 95% of patients had spontaneous bleeding episodes, and bleeds were considered major for about three-quarters. The median time to diagnosis was about a week, which the researchers said is longer than reported in previous studies.
Most patients (80.6%) were treated with medications to control bleeds, and 93.9% were given at least one line of immunosuppressive therapy, which is intended to help control the autoimmune attacks underlying the bleeding.
A total of 91 patients (55.2%) died during the study period. This mortality rate is higher than what’s been observed in previous reports of Caucasian patients, in which about a quarter of the patients died, according to the authors.
While bleed-related deaths were infrequent, half of the deaths were attributed to severe responses to infection (sepsis) arising due to immunosuppressive therapy. Moreover, median hospital stay lengths were significantly longer for patients on more intensive immunosuppressive regimens.
More than half of the patients (53.9%) achieved complete disease remission during the study, in a median of 244 days, or about eight months.
Statistical analyses also indicated patients older than 75 had a higher mortality rate and a lower likelihood of achieving disease remission. Older patients also took longer to reach remission.
Failure to achieve remission and taking longer time to reach remission were also significant predictors of mortality.
“Further prospective studies with a standard or novel protocol for AHA treatment are required to further evaluate the efficacy of different treatment modalities,” the team wrote.
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