Chemotherapy for AIDS-Related Lymphomas

Publisher Website
Google Scholar
Abstract
Kaplan et al. (June 5 issue)1 “recommend that low-dose chemotherapy be considered for most patients with HIV [human immunodeficiency virus] infection and non-Hodgkin's lymphoma,” but their results do not convincingly support a general recommendation to use low-dose chemotherapy in patients with high CD4+ counts. Higher CD4+ counts are associated with significantly more complete responses and longer median survival, but in this trial, patients were not stratified according to CD4+ count.2 Although the authors controlled for the absolute CD4+ count in the analysis of survival, the primary end point, and found no difference between the treatment groups, the study did not have sufficient numbers of patients in the subgroups with high CD4+ counts. A “prospective” calculation of the power to detect a difference (two-tailed α = 0.05) in survival from 6 to 9 months (as the authors proposed), given the trial's approximate time of 42 months to accrue patients and follow-up of 24 months, yields a power of 50 percent with respect to the subgroup with >100 CD4+ cells per cubic millimeter (50 patients per group) and a power of 34 percent for the subgroup with >200 CD4+ cells per cubic millimeter (30 patients per group). Alternatively, using an equivalence-design approach (α = 0.2), this study would have had β values of approximately 0.24 and 0.39, respectively, where a β value of 0.05 is desirable. Thus, the authors could not make definitive conclusions about the absence of difference or equivalence between the treatment groups in the subgroups of patients with high CD4+ counts.