Table 3.

Multivariate Cox proportional hazards model predicting rate of return for a subsequent donation attempt^*

Predictor	OR (99.9% CI)	p value
Deferral reason
Not deferred	(Reference)
Hb	1.12 (1.06‐1.18)	<0.001
Travel related	0.84 (0.76‐0.94)	<0.001
Short‐term medical	0.69 (0.64‐0.74)	<0.001
Long‐term medical	0.81 (0.68‐0.98)	<0.001
Miscellaneous	0.66 (0.55‐0.81)	<0.001
Experience
Experienced donors	(Reference)
First‐time donors	0.87 (0.86‐0.89)	<0.001
Novice donors	0.57 (0.56‐0.58)	<0.001
Reactivated donors	0.51 (0.49‐0.53)	<0.001
Interaction of deferral reason and experience
First‐time donor × Hb deferral	0.55 (0.51‐0.60)	<0.001
First‐time donor × travel‐related deferral	0.94 (0.83‐1.07)	0.120
First‐time donor × short‐term medical deferral	0.97 (0.86‐1.09)	0.368
First‐time donor × long‐term medical deferral	0.70 (0.55‐0.89)	<0.001
First‐time donor × miscellaneous deferral	0.83 (0.67‐1.02)	0.003
Novice donor × Hb deferral	0.92 (0.86‐1.00)	<0.001
Novice donor × travel‐related deferral	1.03 (0.90‐1.18)	0.469
Novice donor × short‐term medical deferral	1.06 (0.96‐1.17)	0.044
Novice donor × long‐term medical deferral	1.02 (0.80‐1.29)	0.820
Novice donor × miscellaneous deferral	1.05 (0.83‐1.32)	0.503
Reactivated donor × Hb deferral	0.68 (0.56‐0.82)	<0.001
Reactivated donor × travel‐related deferral	0.97 (0.74‐1.26)	0.674
Reactivated donor × short‐term medical deferral	0.80 (0.66‐0.97)	<0.001
Reactivated donor × long‐term medical deferral	1.07 (0.67‐1.71)	0.627
Reactivated donor × miscellaneous deferral	1.04 (0.75‐1.43)	0.725
Age	1.00 (1.00‐1.00)	<0.001
Blood group: ABO
O	(Reference)
A	0.95 (0.94‐0.96)	<0.001
B	0.86 (0.84‐0.88)	<0.001
AB	0.80 (0.78‐0.83)	<0.001
Blood type: D
Negative	(Reference)
Positive	0.92 (0.90‐0.93)	<0.001
Sex
Male	(Reference)
Female	0.80 (0.79‐0.81)	<0.001

^*  A total of 177 donors had missing data on sex, blood type, and/or donation location, the majority of whom were first‐time donors (97%). We therefore removed these donors for this analysis only.