Table 1. Demographic description and some characteristics related to donation in the study.

Variables	Levels	n	%
Age group, years	18–20	8,870	17.0
	21–30	18,911	36.3
	31–40	10,683	20.5
	41–50	7,932	15.2
	51–65	5,763	11.0
Gender	Female	27,767	53.2
	Male	24,392	46.8
Recruitment place	Intramural a	16,436	31.5
	Extramural b	35,723	68.5
Type of donation	Altruistic c	39,766	76.2
	Replenishment d	12,393	23.8
Frequency of donation	First Time	23,763	45.6
	Not repetitive	15,617	29.9
	Repetitive	12,779	24.5
Type of extraction grouped	Total Blood	47,581	91.2
	Apheresis	4,578	8.8
Place of residence	Medellín	30,566	58.8
	Others of the Metropolitan Area	15,151	29.2
	Outside the Metropolitan Area	6,246	12.0

^a Intramural means donors were from the blood bank of the hospital

^b Extramural means donors were from companies and universities

^c Altruistic donors were unpaid and donated to the blood bank voluntarily

^d Replenishment donors were directing their donation to replenish a particular patient