How Do Patient and Physician Attitudes Drive Choices in Antiplatelet Therapy for Thrombocytopenia?

Patients with a hematologic malignancy and thrombocytopenia typically are treated with antiplatelet drugs, but there is little information to help clinicians balance the potential benefits of this therapy with the risks of bleeding. In a “choice experiment” presented at the 23rd Congress of the European Hematology Association, researchers described how physician and patient attributes – in the absence of prospective data or evidence-based guidelines – help shape clinical decision-making.

Results of the study revealed that physicians’ assessment of bleeding and thrombotic risk “consistently and logically” influenced choice of one management strategy over another, according to lead study author Avi Leader, MD, of the Maastricht University Medical Center in the Netherlands.

“Although this study does not show which management strategy is the optimal approach in managing antiplatelet drugs in these patients, the findings provide physicians with a framework of reasonable decisions by shedding light on current practice,” Dr. Leader told ASH Clinical News. “Because there are no patient data in this setting, this ‘hive knowledge’ represents the best evidence to guide practice.”

To gather information about hematologists’ decisionmaking process for patients with hematologic malignancies and thrombocytopenia, the researchers first created 18 clinical vignettes, based on interviews with 11 Israeli or Dutch hematologists. Each case scenario addressed five relevant clinical attributes:

  • antiplatelet drug indication
  • gastrointestinal (GI) bleeding (either within 3 weeks or within 4 months of presentation)
  • malignancy and treatment type
  • platelet level
  • time since indication

These vignettes were designed to reveal patient- and physician-related characteristics associated with choice of antiplatelet therapy, as well as how physician assessment of bleeding and/or thrombotic risks correlate with antiplatelet therapy choice.

Next, the authors sent the survey to hematologists in Israel, the Netherlands, and Italy, asking them about their management strategy for each patient scenario. Patient management was defined as three consecutive steps, with each step comprising a choice between two different options:

  • hold antiplatelet therapy vs. continue antiplatelet therapy
  • continue same antiplatelet therapy (without transfusion) vs. transfusion or modifying antiplatelet therapy
  • modifying antiplatelet therapy (with or without transfusion) vs. transfusion and continuing same antiplatelet therapy

A total of 145 physicians participated in the survey, and 434 cases were answered in full.

Choice of antiplatelet therapy in the vignette cases varied widely by patient presentation. In patients with platelet counts of 20×109/L, for example, physicians were 3.45 times more likely to hold antiplatelet therapy versus continuing therapy, compared with patients presenting with platelet counts of 40×109/L (odds ratio [OR] = 0.29; 95% CI 0.12-0.70; p=0.006).

In patients with major gastrointestinal (GI) bleeding, physicians also were more likely to hold antiplatelet therapy rather than continuing antiplatelet therapy (OR=0.22; 95% CI 0.07-0.68; p=0.008).

Comparatively, in patients with ST-elevation myocardial infarction (STEMI) who received drug-eluting stents (DES) and dual aspirin and clopidogrel therapy, physicians were more likely to continue antiplatelet therapy versus holding treatment (OR=33.13; 95% CI 6.26-175.34; p<0.0001).

The researchers also determined that physicians who practiced at institutions with management protocols were more likely to continue antiplatelet therapy (OR=4.22; 95% CI 1.17-15.21; p=0.0277).

The following patient attributes emerged as the factors significantly associated with physicians choice to modify therapy (with platelet transfusion or changing from dual to single antiplatelet therapy) or not:

  • platelets 20,000/μL (OR=16.65; 95% CI 5.07-54.72; p<0.0001)
  • STEMI with DES on dual aspirin and clopidogrel (OR=61.03; 95% CI 14.03-265.57; p<0.0001)
  • major GI bleeding within three weeks of presentation (OR=2.63; 95% CI 1.10-6.33; p=0.0304)
  • major GI bleeding within four months of presentation (OR=2.95; 95% CI 1.04-8.38; p=0.0423)

While the researchers concluded that there was “surprisingly little variance between physicians” in their management choices, they noted that the study might not be reflective of the choices made by these physicians in real-world practice, given the limitations of using survey responses rather than previous patient cases.

In the future, Dr. Leader said, he would like to see prospective studies about the incidence and predictors of bleeding and thrombosis in this patient setting. “Our research group is currently performing a prospective observational study – the MATTER study – with these exact goals,” he added. “This study also will evaluate outcomes based on management, using the management strategies chosen by physicians in the present study.” Based on the results reported with this study, he noted, the researchers will include the clinical variables identified in this current study as possible confounders.

Dr. Leader also identified additional research avenues for this patient population, like assessing safety outcomes associated with platelet transfusions – particularly those used to enable antiplatelet therapy continuation. “Our study suggests that this strategy is widely used, even though no evidence supports or refutes its use,” he concluded.

The authors report no conflicts of interest.

Reference

Leader A, Cate VT, Cate-Hoek AT, et al. Factors influencing management of antiplatelet drugs in thrombocytopenic patients with hematological malignancy. Abstract #S140. Presented at the 23rd Congress of the European Hematology Association, June 15, 2018; Stockholm, Sweden.

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