- In a three arm randomized double blind placebo-controlled trial,
302 adult volunteers were given E. angustifolia, E. purpurea,
or placebo. Population studies included European adults in military
settings. Some URI's were documented retrospectively. The
results were analyzed on the basis of intent to treat. There were
13 patients not included in the intent to treat analysis. The
patients excluded were either accidentally unblinded or dropped out
in the enrollment period. A further 45 patients dropped out during
the study, but were included in the intent to treat analysis.
In the twelve-week period, the time until occurrence of first URI was
66 days, 69 days, and 65 days respectively. Occurrence of infection
was 32%, 29.3%, and 36.7% respectively. These differences were
not statistically significant.
- The power of the study was insufficient. For adequate statistical
power, approximately 1000 participants would have been required.