摘要：在调查治疗普通感冒中的安慰剂效应时，研究人员发现一些中度的、微妙的效应，比如吃药时不理会药的成分，特别是在那些信任某一种治疗方法的人群中。研究人员对719名12至80岁的病患随机开展了这项四臂实验（无丸、安慰剂、紫锥花盲及紫锥花非盲），最终发现那些被随机安排到无丸组的病人比那些服药的病人，不管他吃的是什么药，患病时间更长，程度更严重。具体来说，那些被随机安排服药的病人患感冒的时间比不服药的病人平均短0.16至0.69天，而且感冒的严重程度也要轻8％至17％。那些对紫锥花的疗效深信不疑并且服药的病人，不管他是否服用了含有紫锥花的药丸，其患病时间明显缩短，症状也明显较轻。具体来说，那些服了药并且为紫锥花的疗效打了高分的病人患病时间要少1.31至2.58天，症状要轻26％至29％。文章作者总结称，这些发现揭示了与预期和药片分配相关的微小但有意义的效应，而且支持了在医学决定中应将患者对治疗方法的信任和感受考虑在内的观点。
生物探索推荐英文论文摘要：
Placebo Effects and the Common Cold: A Randomized Controlled Trial
PURPOSE We wanted to determine whether the severity and duration of illness caused by the common cold are influenced by randomized assignment to open-label pills, compared with conventional double-blind allocation to active and placebo pills, compared with no pills at all.
METHODS We undertook a randomized controlled trial among a population with new-onset common cold. Study participants were allocated to 4 parallel groups: (1) those receiving no pills, (2) those blinded to placebo, (3) those blinded to echinacea, and (4) those given open-label echinacea. Primary outcomes were illness duration and area-under-the-curve global severity. Secondary outcomes included neutrophil count and interleukin 8 levels from nasal wash at intake and 2 days later.
RESULTS Of 719 randomized study participants, 2 were lost and 4 exited early. Participants were 64% female, 88% white, and aged 12 to 80 years. Mean illness duration for each group was 7.03 days for those in the no-pill group, 6.87 days for those blinded to placebo, 6.34 days for those blinded to echinacea, and 6.76 days for those in the open-label echinacea group. Mean global severity scores for the 4 groups were no pills, 286; blinded to placebo, 264; blinded to echinacea, 236; and open-label echinacea, 258. Between-group differences were not statistically significant. Comparing the no-pill with blinded to placebo groups, differences (95% confidence interval [CI]) were –0.16 days (95% CI, –0.90 to 0.58 days) for illness duration and –22 severity points (95% CI, –70 to 26 points) for global severity. Comparing the group blinded to echinacea with the open-label echinacea group, differences were 0.42 days (95% CI, –0.28 to 1.12 days) and 22 severity points (95% CI, –19 to 63 points). Median change in interleukin 8 concentration and neutrophil cell count, respectively by group, were 30 pg/mL and 1 cell for the no-pill group, 39 pg/mL and 1 cell for the group binded to placebo, 58 pg/mL and 2 cells for the group blinded to echinacea, and 70 pg/mL and 1 cell for the group with open-label echinacea, also not statistically significant. Among the 120 participants who at intake rated echinacea’s effectiveness as greater than 50 on a 100-point scale for which 100 is extremely effective, illness duration was 2.58 days shorter (95% CI, –4.47 to –0.68 days) in those blinded to placebo rather than no pill, and mean global severity score was 26% lower but not significantly different (–97.0, 95% CI, –249.8 to 55.8 points). In this subgroup, neither duration nor severity differed significantly between the group blinded to echinacea and the open-label echinacea group.
CONCLUSIONS Participants randomized to the no-pill group tended to have longer and more severe illnesses than those who received pills. For the subgroup who believed in echinacea and received pills, illnesses were substantively shorter and less severe, regardless of whether the pills contained echinacea. These findings support the general idea that beliefs and feelings about treatments may be important and perhaps should be taken into consideration when making medical decisions.
Key Words: Double-blind method • clinical trial • common cold • expectancy • placebo effect • upper respiratory tract infection
