– Despite improvements over the past 60 years, intracranial hemorrhage (ICH) remains a significant complication in hemophilia, occurring most frequently among patients with severe forms of the disease, according to a large-scale meta-analysis involving 56 studies and nearly 80,000 patients.

Anne-Fleur Zwagemaker, Amsterdam University Medical Center Will Pass/MDedge News

Anne-Fleur Zwagemaker

The consequences of a single incident of ICH can be irreparable and life-changing, so clinician knowledge of incidence rates and risk factors is essential, said lead author Anne-Fleur Zwagemaker, a PhD candidate from Amsterdam University Medical Center.

“Intracranial hemorrhage is one of the most severe and fearful complications in hemophilia,” Ms. Zwagemaker said in a presentation at the annual congress of the European Association for Haemophilia and Allied Disorders. “Our aim was to give more precise estimates of ICH numbers and risk factors in hemophilia.”

The review is notable for its scale and quality. After eliminating studies with fewer than 50 patients or other insufficiencies, the investigators were left with 56 studies conducted between 1960 and 2018, involving 79,818 patients with hemophilia. With a mean observation period of 12 years, the data encompassed almost 1 million person-years of data.

Across all studies, 1,508 ICH events were reported. Incidence and mortality rates were 400 and 80 per 100,000 person-years, respectively.

To optimize accuracy, the investigators further restricted studies to those with a sample size of at least 365 patients, leading to a pooled incidence rate of 3.8%. Studies with relevant data showed that about half of the cases of ICH (48%) were spontaneous. Regarding most common bleed locations, about two-thirds were either subdural (30%) or intracerebral (32%).

Pooled incidence rates of ICH have decreased steadily over time, from 7%-8% during the 1960-1979 time period, to 5%-6% from 1980-1999, and most recently to about 3%.

Mortality rates during the same time periods decreased in a similar fashion, from 300, to 100, to 75 deaths per 100,000 person-years.

Additional analysis revealed an expected relationship between disease severity and likelihood of ICH. Mild cases of hemophilia had an ICH incidence rate of 0.9%, moderate cases had a rate of 1.3%, and severe cases topped the scale at 4.5%, entailing an incidence rate ratio of 2.7 between severe and nonsevere patients.

“I think our data show that in hemophilia, ICH is still a very important and frequent complication,” Ms. Zwagemaker said. “Luckily, we also see a decline in numbers, but I think it’s still very important that we identify those at risk in hemophilia and that we acknowledge it’s still a very important problem.”

Dr. Zwagemaker reported having no relevant financial disclosures.

SOURCE: Zwagemaker AF et al. EAHAD 2019, Abstract OR08.