Results:
The measurements made at 72nd hour were significantly higher than those made at 48th hour (median: 8.9 vs 4.5mm, p=0.01). In those subjects with indurations at either or both time points (n=74), the readings taken at 72nd hour were on average 2.1mm (95% confidence interval: 0.3-3.1mm) larger than those at 48th hour. Using an induration of>15mm diameter to define a positive result, there were more positive test results at 72nd hour (24) compared to 48th hour (20).