Table 1
Relationship of 24 hour readings to results at 72 hours
Induration at 24 hours (mm)
No of subjects ⩾10 mm at 72 hours
No of subjects <10 mm at 72 hours
0
21
545
1–4
27
137
5–9
101
46
10–14
112
1
15–19
53
1
20–24
16
0
⩾25
2
0