Melchart D, Walther E, Linde K, Brandmaier R, Lersch C
Center for Complementary Medicine Research, Technische Universität, Munich, Germany.
Arch Fam Med. 1998 Nov-Dec;7(6):541-5. doi: 10.1001/archfami.7.6.541.
To investigate the safety and efficacy of 2 extracts of echinacea for preventing upper respiratory tract infections.
Three-armed, randomized, double-blind, placebo-controlled trial.
Four military institutions and 1 industrial plant.
Three hundred two volunteers without acute illness at time of enrollment.
Ethanolic extract from Echinacea purpurea roots, Echinacea angustifolia roots, or placebo, given orally for 12 weeks.
Time until the first upper respiratory tract infection (time to event). Secondary outcome measures were the number of participants with at least 1 infection, global assessment, and adverse effects.
The time until occurrence of the first upper respiratory tract infection was 66 days (95% confidence interval [CI], 61-72 days) in the E angustifolia group, 69 days (95% CI, 64-74 days) in the E purpurea group, and 65 days (95% CI, 59-70 days) in the placebo group (P = .49). In the placebo group, 36.7% had an infection. In the treatment groups, 32.0% in the E angustifolia group (relative risk compared with placebo, 0.87; 95% CI, 0.59-1.30) and 29.3% in the E purpurea group (relative risk compared with placebo, 0.80; 95% CI, 0.53-1.31) had an infection. Participants in the treatment groups believed that they had more benefit from the medication than those in the placebo group (P = .04). Adverse effects were reported by 18 subjects in the E angustifolia group, 10 in the E purpurea group, and 11 in the placebo group.
In this study a prophylactic effect of the investigated echinacea extracts could not be shown. However, based on the results of this and 2 other studies, one could speculate that there might be an effect of echinacea products in the order of magnitude of 10% to 20% relative risk reduction. Future studies with much larger sample sizes would be needed to prove this effect.
研究紫锥菊的两种提取物预防上呼吸道感染的安全性和有效性。
三臂、随机、双盲、安慰剂对照试验。
四个军事机构和一家工厂。
302名入组时无急性疾病的志愿者。
紫锥菊根乙醇提取物、狭叶紫锥菊根乙醇提取物或安慰剂，口服12周。
首次发生上呼吸道感染的时间（事件发生时间）。次要结局指标为至少发生1次感染的参与者人数、整体评估和不良反应。
狭叶紫锥菊组首次发生上呼吸道感染的时间为66天（95%置信区间[CI]，61 - 72天），紫锥菊组为69天（95%CI，64 - 74天），安慰剂组为65天（95%CI，59 - 70天）（P = 0.49）。安慰剂组中，36.7%的人发生了感染。在治疗组中，狭叶紫锥菊组32.0%的人发生了感染（与安慰剂相比的相对风险，0.87；95%CI，0.59 - 1.30），紫锥菊组29.3%的人发生了感染（与安慰剂相比的相对风险，0.80；95%CI，0.53 - 1.31）。治疗组的参与者认为他们从药物中获得的益处比安慰剂组的参与者更多（P = 0.04）。狭叶紫锥菊组有18名受试者报告了不良反应，紫锥菊组有10名，安慰剂组有11名。
在本研究中，未显示所研究的紫锥菊提取物具有预防作用。然而，基于本研究及其他两项研究的结果，可以推测紫锥菊产品可能有降低相对风险10%至20%的效果。需要更大样本量的未来研究来证实这一效果。
