Table 1.

Study sample characteristics by type of survey received

Characteristic	Paper, no. (%)	Electronic, no. (%)
Total number	1486	830
Men	996 (67.0)	537 (64.7)
Women	490 (33.0)	293 (35.3)
Mean age, years (SD)	27.7 (11)	28.3 (11)
Age group
< 19 years	395 (26.6)	86 (10.4)
19–29 years	497 (33.4)	320 (38.6)
30–39 years	310 (20.9)	212 (25.5)
40–49 years	216 (14.5)	157 (18.9)
≥ 50 years	68 (4.6)	55 (6.6)
Follow-up time
1 year	507 (34.1)	291 (30.1)
2 years	597 (40.2)	361 (43.5)
5 years	382 (25.7)	178 (21.4)

SD = standard deviation.