I am puzzled by Whitley and colleagues' statement that, for the treatment of herpes zoster, they "do not recommend that corticosteroids be used without concomitant antiviral therapy" [1]. Their 2 x 2 factorial design allows analysis of the contribution of acyclovir and prednisone to the effectiveness of treatment. This is shown in the last two columns of their Table 2, in which it can be seen that patients who received prednisone had statistically significantly better results than those who received placebo in all quality-of-life measures at their 1-month evaluation. On the other hand, acyclovir recipients showed improvement only in time to return to 100% usual activity. This comparison should be valid if the effectiveness of each drug and the use of the other study drug do not interact. The authors describe no such interaction, and, although the data they present are incomplete in this regard, no interaction is apparent in Table 2.

Although I would agree with the authors' conclusion that "concomitant administration of acyclovir and prednisone provides substantial benefit for persons with herpes zoster," their data suggest that patients may achieve this benefit with prednisone alone. If the authors believe otherwise, they should at least present the quality-of-life data for patients who receive acyclovir and prednisone compared with data for patients who receive prednisone alone (adjusted for baseline differences).