Platelet transfusion tied to much higher risk of death in TTP: Study
Researchers suggest patients requiring procedure may have more severe disease
Platelet transfusions more than double the risk of death among people with thrombotic thrombocytopenic purpura (TTP), according to a review of published studies.
However, because platelet transfusions did not cause immediate harm or organ damage, researchers suggested that patients requiring these transfusions may have more severe disease and are more likely to die.
“Our results could signify harm of platelet transfusions or a greater disease severity of transfused TTP patients,” they wrote.
The review, “Investigating the impact of platelet transfusions on adverse outcomes in patients with thrombotic thrombocytopenic purpura: A systematic review of published studies,” was published in Thrombosis Research as a letter to the editors-in-chief.
TTP caused by deficiency in key enzyme
TTP is caused by a deficiency in ADAMTS13, an enzyme that prevents platelets, the cell fragments that help blood clot, from forming clots when they aren’t needed. Without ADAMTS13, platelets form tiny clots inside small blood vessels, which can damage organs, destroy red blood cells, and lower platelet counts, increasing the risk of bleeding.
Platelet transfusions, or infusing platelets directly into the bloodstream, have been considered for patients with severely low platelet counts, active bleeding, or in preparation for invasive procedures such as surgery. However, giving extra platelets to a TTP patient with an already high risk of blood clotting raises concerns of adverse events.
While early reports of side effects associated with platelet transfusion in TTP date back decades, later studies generated conflicting results.
Faced with contradictory evidence, researchers in Italy conducted a systematic review of published studies that evaluated the safety of platelet transfusions in people with TTP.
The team selected 11 studies for the analysis that involved 13,728 TTP patients, most of whom were women (65%). Among them, 1,548 (11%) received at least one platelet transfusion.
TTP type was reported for 759 patients, all of whom had immune-mediated TTP, where the immune system mistakenly attacks ADAMTS13. Nearly all patients received plasma exchange or infusion (99.9%), while most also received corticosteroids (81.2%) and about one-third were given rituximab (36.1%).
Death risk more than double for TTP patients who received platelet transfusion
According to the analysis, more than twice as many TTP patients who underwent a platelet transfusion died of any cause (all-cause mortality) compared with non-transfused patients (18% vs.. 8%).
“This could reflect harm of transfusions, calling for continued caution in platelet transfusion practices during acute TTP,” the researchers wrote. “Another explanation could be confounding by indication, since TTP patients requiring platelet transfusions often present with more severe disease manifestations and a higher baseline risk of complications.”
The researchers noted no differences between the two groups for secondary safety outcomes, including fatal and non-fatal heart attacks, coma, seizures, and events related to blood flow in the brain.
Our results show that TTP patients who undergo platelet transfusions have a higher all-cause mortality compared to non-transfused subjects. This finding may indicate risks associated with platelet transfusions or, more plausibly, residual confounding by disease severity.
Death within one day of disease onset or diagnosis was similar between transfused and non-transfused TTP patients, as was the death rate within one day of the latest platelet transfusion.
These data suggest that “platelet transfusions did not cause immediate harm or organ damage and therefore strengthen the hypothesis that transfused TTP patients are more critical and more likely to die compared to non-transfused ones,” the team wrote.
Among patients with less than 10% ADAMTS13 activity, there was also a higher risk of death associated with platelet transfusions. Still, the elevated risk was statistically nonsignificant relative to non-transfused patients, meaning the difference may have occurred by chance.
“Our results show that TTP patients who undergo platelet transfusions have a higher all-cause mortality compared to non-transfused subjects,” the researchers wrote. “This finding may indicate risks associated with platelet transfusions or, more plausibly, residual confounding by disease severity. Future studies with rigorous designs and adjustment strategies for underlying disease severity and transfusion indication will ultimately shed light on the safety of platelet transfusions in acute TTP.”
About the Author
