We read with interest the article by Fraser-Andrews and colleagues1 and think that analysis of their data requires qualifying comments. Conclusions drawn are based on the failure to demonstrate statistically significant differences between patients with Sézary syndrome (SS) treated with extracorporeal photopheresis (ECP) (n=29) and 2 groups of patients treated without ECP (n=15). However, the statistical power to detect such differences, if present, was small, given the low number of subjects. Thus, their results that relative to the combined non-ECP group, ECP-treated patients had their risk of dying cut nearly in half (hazard ratio, 0.56) and median survival time extended 150% (39 vs 26.5 months) were not statistically significant. Owing to the 4-fold degree of uncertainty in the death hazard ratio, we ask the authors to provide the confidence interval for the median survival time of their ECP-treated group, as the upper limit may be as high as the median survivals of ECP-treated patients reported by us and others (60-100+ months) and thus may not be statistically significantly worse, as implied in their report.
Stevens SR, Bowen GM, Duvic M, King LE, Knobler R, Lim HW, Margolis D, Parry EJ, Rook AH, Stricklin GP, Suchin KR, Tharp MD, Vonderheid E, Zic JA. Effectiveness of Photopheresis in Sézary Syndrome. Arch Dermatol. 1999;135(8):995-a-997. doi:10-1001/pubs.Arch Dermatol.-ISSN-0003-987x-135-8-dlt0899