Table 1
Baseline characteristics of study groups
Postal group
Opportunistic group
Control group
Number
124
146
136
Age (mean (SD))
25.3 (4.6)
24.5 (4.3)
23.3 (4.0)
Deprivation category
1–2
28
25
32
3–5
47
58
48
6–7
34
36
44
Missing
15
17
22