Primary Outcomes: No-Pill Group vs Blinded to Placebo Group
| Outcome | No Pill | Blinded to Placebo | Between-Group Differences |
|---|---|---|---|
| SF-8 = SF-8 Health Survey; WURSS-21 = 21-item Wisconsin Upper Respiratory Symptom Survey. | |||
| a Global severity represents area-under-the-curve, with WURSS-21 scores the y-axis and illness duration the x-axis. | |||
| b Because global severity was skewed, we first transformed using Box Cox methods, then adjusted for potential confounders with a mixed general linear model, controlling for symptom duration before entry, cold severity at entry, age, sex, ethnicity, education, income, smoking status, physical and mental health (SF-8), and randomized assignment to the 3 clinician-related groups. | |||
| c Belief in echinacea (expectancy) was assessed by asking, “How effective do you think that echinacea is?” Participants responded by marking a visual analogue scale, which ranged from 0 (totally ineffective) to 100 (extremely effective). | |||
| Sample size (protocol completers), n | 173 | 76 | – |
| Illness duration, mean (95% CI), d | 7.03 (6.51 to 7.56) | 6.87 (6.33 to 7.41) | −0.16 (−0.90 to 0.58) |
| Illness duration, median (95% CI), d | 6.42 (6.13 to 7.21) | 6.47 (5.82 to 7.12) | 0.05 (−0.78 to 0.88) |
| Global severity score, mean (95% CI)a | 286 (249 to 323) | 264 (233 to 296) | −22.0 (−70.3 to 26.3) |
| Global severity score, median (95% CI)a | 220 (189 to 238) | 206 (177 to 256) | −14.0 (−59.4 to 31.3) |
| Transformed and adjusted global severity score (95% CI)b | 10.3 (9.9 to 10.7) | 10.0 (9.7 to 10.4) | −0.30 (−0.76 to 0.46) |
| Participants who rated echinacea’s effectiveness >50c | |||
| Subsample size, n | 32 | 25 | – |
| Illness duration, mean (95% CI), d | 8.41 (7.09 to 9.72) | 5.83 (4.44 to 7.23) | −2.58 (−4.47 to −0.68) |
| Illness duration, median (95% CI), d | 7.95 (6.26 to 10.27) | 4.45 (4.01 to 6.70) | −3.50 (−5.80 to −1.20) |
| Global severity score, mean (95% CI)a | 374 (263 to 484) | 277 (171 to 383) | −97.0 (−249.8 to 55.8) |
| Global severity score, median (95% CI)a | 306 (178 to 430) | 237 (115 to 330) | −69.0 (−217.5 to 79.1) |
| Transformed and adjusted global severity score (95% CI)b | 11.3 (10.0 to 12.5) | 10.2 (9.0 to 11.5) | −1.10 (−2.81 to 0.61) |