How low can you go: What is the safe threshold for platelet transfusions in patients with hematologic malignancy in sub-Saharan Africa.

Background: Despite the importance of platelet transfusions in treatment of hematologic cancer patients, the optimal platelet count threshold for prophylactic transfusion is unknown in sub-Saharan Africa.

Methods: We followed patients admitted to the Uganda Cancer Institute with a hematological malignancy in 3 sequential 4-month time-periods using incrementally lower thresholds for prophylactic platelet transfusion: platelet counts ≤ 30 x 109/L in period 1, ≤ 20 x 109/L in period 2, and ≤ 10 x 109/L in period 3. Clinically significant bleeding was defined as WHO grade ≥ 2 bleeding. We used generalized estimating equations (GEE) to compare the frequency of clinically significant bleeding and platelet transfusions by study period, adjusting for age, sex, cancer type, chemotherapy, baseline platelet count, and baseline hemoglobin.

Results: Overall, 188 patients were enrolled. The median age was 22 years (range 1-80). Platelet transfusions were given to 42% of patients in period 1, 55% in period 2, and 45% in period 3. These transfusions occurred on 8% of days in period 1, 12% in period 2, and 8% in period 3. In adjusted models, period 3 had significantly fewer transfusions than period 1 (RR = 0.6, 95% CI 0.4-0.9; p = 0.01) and period 2 (RR = 0.5, 95% CI 0.4-0.7; p<0.001). Eighteen patients (30%) had clinically significant bleeding on at least one day in period 1, 23 (30%) in period 2, and 15 (23%) in period 3. Clinically significant bleeding occurred on 8% of patient-days in period 1, 9% in period 2, and 5% in period 3 (adjusted p = 0.41). Thirteen (21%) patients died in period 1, 15 (22%) in period 2, and 11 (19%) in period 3 (adjusted p = 0.96).

Conclusion: Lowering the threshold for platelet transfusion led to fewer transfusions and did not change the incidence of clinically significant bleeding or mortality, suggesting that a threshold of 10 x 109/L platelets, used in resource-rich countries, may be implemented as a safe level for transfusions in sub-Saharan Africa.