Reporting on methods of subgroup analysis in clinical trials: a survey of four scientific journals

Results of subgroup analysis (SA) reported in randomized clinical trials (RCT) cannot be adequately interpreted without information about the methods used in the study design and the data analysis. Our aim was to show how often inaccurate or incomplete reports occur. First, we selected eight methodological aspects of SA on the basis of their importance to a reader in determining the confidence that should be placed in the author's conclusions regarding such analysis. Then, we reviewed the current practice of reporting these methodological aspects of SA in clinical trials in four leading journals, i.e., the New England Journal of Medicine, the Journal of the American Medical Association, the Lancet, and the American Journal of Public Health. Eight consecutive reports from each journal published after July 1, 1998 were included. Of the 32 trials surveyed, 17 (53 percent) had at least one SA. Overall, the proportion of RCT reporting a particular methodological aspect ranged from 23 to 94 percent. Information on whether the SA preceded/followed the analysis was reported in only 7 (41 percent) of the studies. Of the total possible number of items to be reported, NEJM, JAMA, Lancet and AJPH clearly mentioned 59, 67, 58 and 72 percent, respectively. We conclude that current reporting of SA in RCT is incomplete and inaccurate. The results of such SA may have harmful effects on treatment recommendations if accepted without judicious scrutiny. We recommend that editors improve the reporting of SA in RCT by giving authors a list of the important items to be reported

Effects of vitamin A supplementation during pregnancy and early lactation on body weight of South African HIV-infected women.

Effects of vitamin A supplementation during pregnancy and early lactation on maternal weight among HIV-1-seropositive South African women were examined. Three hundred twelve HIV-seropositive pregnant women between 28 and 32 weeks gestation were studied as part of a randomized, double-blind, placebo-controlled trial at the King Edward VIII Hospital in Durban, South Africa. Patients were randomized to receive placebo or 5,000 IU of retinyl palmitate and 30 mg of beta-carotene daily during pregnancy. At delivery, patients received placebo or 200,000 IU of retinyl palmitate. The main outcome measures were prenatal and postnatal maternal weight and weight loss at three months after delivery as measured in body mass index (BMI). Supplementation of vitamin A was not associated with improvements in prepartum weight gain but was significantly associated with improved weight retention three to six months after delivery (p = 0.02). The benefit of vitamin A supplementation appeared to be confined to subgroups with baseline CD4+ count < 200 cells/microL and serum retinol 0-20 micrograms/dL. Similar trends were observed in maintenance of postpartum BMI. However, no statistically significant associations were observed. Although there was no benefit of vitamin A supplementation on prepartum weight gain, a benefit on maintenance of postnatal weight was observed. The benefit was highest among those who were vitamin A-deficient or whose CD4+ count was < 200 cells/microL presupplementation. In populations for whom antiretroviral therapy is not readily available or accessible, the finding that vitamin A may improve postpartum weight lends some hope to a relatively inexpensive treatment which could be used for helping ameliorate some weight loss which is common during HIV infection.