PHILADELPHIA—Results of a large study support the recommendation that patients with platelet consumptive disorders only receive platelet transfusions if they exhibit severe or life-threatening bleeding that is refractory to other therapies.
The research indicated that platelet transfusions may increase the risk of arterial thrombosis and mortality among hospitalized patients with thrombotic thrombocytopenic purpura (TTP) and those with heparin-induced thrombocytopenia (HIT).
Platelet transfusions were also associated with a greater risk of acute myocardial infarction in TTP patients.
However, transfused patients with immune thrombocytopenia (ITP) did not have an increased risk of such complications.
The study did not establish a causal link between transfusions and complications, as it was retrospective and the researchers did not know the exact timing of events.
However, the complications and the transfusions did occur during the same hospital admission, noted Ruchika Goel, MD, of Johns Hopkins University in Baltimore, Maryland. She presented these findings at the AABB Annual Meeting 2014 (abstract S41-030G).
Dr Goel and her colleagues conducted this study to assess current platelet transfusion practices in the US in hospitalized patients with TTP, HIT, and ITP. The team wanted to explore any associations between transfusions and bleeding, venous and arterial thrombotic events, acute myocardial infarction, stroke, and in-hospital mortality in these patients.
“Currently, very little data are available on the risks and benefits associated with platelet transfusions in various platelet consumptive or disruptive disorders,” Dr Goel said. “Thus, evidence-based platelet transfusion guidelines in these disorders are either non-existent or they’re based on consensus statements, with not much supportive data.”
With this in mind, the researchers analyzed data from the Nationwide Inpatient Sample, a stratified probability sample of 20% of all discharges at community hospitals in the US, which covers more than 1100 hospitals across 47 states. The team looked at 5 years of data spanning the period from 2007 through 2011.
They included patients in whom TTP and ITP were the primary admitting diagnoses and patients in whom HIT was 1 of the top 3 diagnoses. Hospitalizations in which patients had a prior history of thrombosis were excluded, as were hospitalizations with any thrombosis/thromboembolism listed as the primary admitting diagnosis (implying that it was already present at admission).
So the analysis included 10,624 patients with TTP, 6332 with HIT, and 79,980 with ITP. The median ages were 47.4, 61.8, and 47.5, respectively. And platelet transfusions were given to 10.1%, 7.1%, and 25.8% of patients, respectively.
When the researchers adjusted their analysis for age and gender, they discovered a significantly increased risk of bleeding among all transfused patients. The odds ratios (ORs) were 2.3 for TTP, 5.5 for HIT, and 5.1 for ITP patients.
“The odds of platelet transfusion were significantly higher in patients who had bleeding, thus implying that . . . that was the indication for the transfusion—an actual bleeding complication,” Dr Goel said.
The results also showed that none of the transfused patients had a significantly increased risk of venous thrombosis or stroke. The ORs for venous thrombosis were 1.1 for TTP, 0.8 for HIT, and 1.3 for ITP patients. And the ORs for stroke were 1.6, 0.5, and 1.3, respectively.
However, both TTP patients and HIT patients had a significantly increased risk of arterial thrombosis. The ORs were 5.8 for TTP, 3.4 for HIT, and 0.3 for ITP patients.
TTP patients also had a significantly increased risk of acute myocardial infarction. The ORs were 2.0 for TTP, 1.9 for HIT, and 1.3 for ITP patients.
And patients with TTP and HIT had a significantly increased risk of in-hospital mortality. The ORs were 2.0 for TTP, 5.2 for HIT, and 1.1 for ITP patients.
Dr Goel noted that this study had several limitations. The temporality of events was not reported, there was no information on platelet thresholds for transfusion or disease severity and the effect on outcomes, and accuracy was limited by the precision of discharge coding.
Therefore, further studies are needed to assess whether platelet transfusions are directly responsible for complications or if they serve as a surrogate marker for the severity of illness.
“We propose that, until such studies or trials are indeed available, which are very hard [to conduct in] these rare disorders, platelets should continue to be considered relatively contraindicated and used only for severe or life-threatening bleeding which is refractory to other therapies,” Dr Goel concluded.
