Table 2.

Platelet-Dose Adherence and Response to Prophylactic Platelet transfusions, According to Treatment Group

Characteristic	Platelet Dose*
	Low Dose (N = 417)	P Value, Low vs. Medium Dose	Medium Dose (N = 423)	P Value, Medium vs High Dose	High Dose (N = 432)	P Value, High vs. Low Dose
Dose adherence†
Attempted dose‡
Transfusions that were neither HLA-selected nor   volume-reduced and for which attempted   dose was known
No. of transfusions	2333		1708		1343
Transfusions within assigned dose range — %	86	<0.001	98	<0.001	93	0.06
Patients who received ≥1 transfusion that was   neither HLA-selected nor volume-reduced   and had ≥1 transfusions with data on   attempted dose
No. of patients	395		386		381
All transfusions within assigned dose range — %	79	<0.001	92	0.004	86	0.02
At-issue dose§
Transfusions that were neither HLA-selected nor   volume-reduced and for which at–issue dose   was known
No. of transfusions	2278		1669		1320
Transfusions within assigned dose range — %	71	0.007	80	<0.001	70	0.11
Patients who received ≥1 transfusion that was   neither HLA-selected nor volume-reduced   and had ≥1 transfusions with data on   at-issue dose
No. of patients	392		380		380
All transfusions within assigned dose range — %	51	<0.001	63	0.04	55	0.19
Response to prophylactic platelet transfusions
No. of transfusions	2547		1912		1572
Days until next transfusion¶		<0.001		<0.001		<0.001
Median	1.1		1.9		2.9
Interquartile range	0.7–2.1		0.9–3.1		1.2–4.7
No. of transfusions with all data available to calculate   4-hr CCI‖	2193		1646		1386
Pretransfusion platelet count — ×10−3/mm3		0.48		0.08		0.21
Median	9		9		9
Interquartile range	7–16		7–19		7–12
Post-transfusion platelet count — ×10−3/mm3**		<0.001		<0.001		<0.001
Median	22		34		50
Interquartile range	16–30		24–48		33–68
Platelet increment — ×10−3/mm3 ‖		<0.001		<0.001		<0.001
Median	10		19		38
Interquartile range	5–17		11–30		22–54
Post-transfusion CCI — ×10−3/mm3		0.08		0.03		0.98
Median	10		10		11
Interquartile range	5–15		6–16		6–15

^*Platelet doses were as follows: low dose, 1.1×10¹¹ platelets per square meter of body-surface area; medium dose, 2.2×10¹¹ platelets per square meter; and high dose, 4.4×10¹¹ platelets per square meter.

^†Adherence to the prophylactic platelet dose was defined as receipt of a dose that was the assigned transfusion dose ±25%.

^‡The “attempted dose” for apheresis platelets was based on the platelet count at the time of collection. For pooled platelet concentrates, the mean platelet count per concentrate, based on quality-control data, was used to determine how many concentrates to pool.

^§The “at-issue dose” was based on platelet counts obtained from all products just before distribution from the blood-transfusion service.

^¶The analysis of days until next transfusion takes into account data censoring at the time of a granulocyte transfusion, a stem-cell transfusion, or study completion.

^‖Calculations of the corrected count increment (CCI) require complete data on pretransfusion and post-transfusion counts and total platelet counts at issue. The unit of analysis is the transfusion. Here, actual medians and interquartile ranges are presented for pretransfusion and post-transfusion counts, the platelet increment, and the CCI, but the results of statistical comparisons are from a generalized linear model that takes into account that for each patient, the results for various transfusions may be correlated.

^**The post-transfusion platelet count was obtained within 4 hours after transfusion.