On the assumption of a mean (+SD) baseline SLEDAI value of 5.43±5.04 (27), we estimate that the planned sample size would provide an 80 percent chance of detecting a difference in SLEDAI of 3 points or more (on a scale of 0 to 105, with higher scores indicating greater severity), at a significance level 0.05. With allowance for a 20 percent loss to follow-up, the planned sample size was 54 patients per group.