Peanut Allergy

To the Editor: Lack et al. (March 13 issue) 1 used a case–control design to obtain retrospective data showing a relation between topical application of creams containing peanut oil (but not creams that did not contain peanut oil) and the development of peanut allergy. Presumably, the creams were used to treat eczema. Since the patients with peanut allergy and the controls (a healthy group and an atopic group without peanut allergy) were not matched, it is possible that the patients with peanut allergy used creams more often and used a larger number of different creams. Indeed, the prospectively acquired cohort data . . .