As a member of the Data Safety and Monitoring Committee for the recent study by Berson et al,1 I have difficulty accepting the conclusions that "These results support a beneficial effect of 15 000 IU/d of vitamin A..." for several reasons.
First, in the study design, patients were assigned to one of four treatment groups as follows: 15 000 IU/d of vitamin A, plus 3 IU/d of vitamin E (group A); 75 IU/d of vitamin A, plus 3 IU/d of vitamin E (trace group); 15 000 IU/d of vitamin A, plus 400 IU/d of vitamin E (group A+E); and 75 IU/d of vitamin A, plus 400 IU/d of vitamin E (group E).
The data through years 4 and 5 show no significant difference between group A and the trace group (Table and Figure). The authors fail to address these data. Instead, the analysis combines group A and group A+E
Norton EWD. A Randomized Trial of Vitamin A and Vitamin E Supplementation for Retinitis Pigmentosa. Arch Ophthalmol. 1993;111(11):1460. doi:10.1001/archopht.1993.01090110018003