Table 2.

Longitudinal linear regression analyses of patient- and platelet-related variables affecting posttransfusion platelet increments

	1 h after transfusion, n = 5778			18 to 24 h after transfusion, n = 5103
Variable	Platelet increment, × 109/L*	95% confidence interval, × 109/L	P	Platelet increment, × 109/L*	95% confidence interval, × 109/L	P
Patient related
Increase platelet increment
Splenectomy	24.8	15.3 to 34.3	< .001	12.4	2.9 to 21.9	.01
Age†	.1	.05 to .15	.001	-	-	-
Decrease platelet increment
Females with ≥ 2 pregnancies, or males	-8.9	-6.5 to -11.3	< .001	-5.7	-3.4 to -8.0	< .001
Palpable spleen	-3.5	-1.3 to -5.8	.002	-4.4	-2.1 to -6.6	< .001
Amphotericin	-2.7	-1.9 to -3.6	< .001	-2.5	-1.6 to -3.4	< .001
Bleeding	-1.7	-.6 to -2.8	.003	-3.1	-2.0 to -4.3	< .001
Fever	-1.6	-.8 to -2.3	< .001	-2.0	-1.2 to -2.7	< .001
Infection	-1.5	-.7 to -2.3	< .001	-1.8	-.9 to -2.6	< .001
Heparin	-	-	-	-3.8	-1.7 to -5.9	< .001
Weight‡	-.19	-.14 to -.24	< .001	-.15	-.1 to -.2	< .001
Height§	-.14	-.04 to -.23	< .004	-	-	-
Transfusion sequence number¶	-.2	-.13 to -.27	< .001	-.21	-.14 to -.28	< .001
Platelet related
Increase platelet increment
ABO-compatible	4.6	2.7 to 6.5	< .001	6.3	4.3 to 8.2	< .001
Stored ≤48 hours	1.9	1.1 to 2.7	< .001	2.0	1.2 to 2.8	< .001
Decrease platelet increment
Gamma irradiated	-2.8	-1.3 to -4.3	< .001	-	-	-

Only variables with statistically significant effects are included in the table.

-indicates no significant effect.

^*Estimated change in platelet increment/μL at 1 hour or 18 to 24 hours after transfusion

^†An increase in age of 1 year increases platelet increment by 100/μL

^‡An increase in weight of 1 kg decreases platelet increment by -190/μL or -150/μL at 1 hour or 18 to 24 hours after transfusion, respectively

^§An increase in height of 1 cm decreases platelet increment by -140/μL at 1 hour after transfusion

^¶An increase of 1 in the transfusion sequence number decreases platelet increment by -200/μL or -210/μL at 1 hour and 18 to 24 hours after transfusion, respectively