Placebo

helenClaire · Post by **helenClaire** » 2005-12-02 15:59

前儿我先生和我提起，他看一个啥啥药治啥啥皮肤癣的三期临床数据，Placebo有效率达35%。

我紧着问真药的有效率多少。

听说有的药，多年研制，等上了临床，不如Placebo有效，真是欲哭无泪啊。

要是某个大夫能把35%得疑难症、公认尚无良药的病人治好，我早就敬他/她是神医了。

我感慨很多。一个愿望就是，现在没治的病都应该有Placebo，而且至少有三个。那么病人连试三次，不少就不治自逾了。

什么独传秘方，国宝神医的幌子，都能增加心理暗示作用。难怪圣经上说“信的人有福了”，如果已经知道是Placebo，江湖术士在骗人，那有效率就大大下降了。我这不信的人，等于白白放弃了35%的治愈率。亏啦。

当然，领导说35%比常见比例高啦，谁来当这个有说服力的骗子，也成问题。

我还是不太甘心。。。

tiffany · Post by **tiffany** » 2005-12-02 16:31

真这么有效？看来这个皮肤病的病根儿３５％还在心理啊。

对了，前几天我们这儿有人来做报告说：抽烟喝酒的人群老年痴呆比例比较低；今天看文献居然就看到一篇说尼古丁修复压力引起的细胞间联系减弱。

silkworm · Post by **silkworm** » 2005-12-02 16:48

tiffany wrote:对了，前几天我们这儿有人来做报告说：抽烟喝酒的人群老年痴呆比例比较低

在寿命一样长的前提下么?

tiffany · Post by **tiffany** » 2005-12-02 16:53

this is a very good question! but I did not go to the seminar, so, "I do not know, I do not know" (quote his holyness the dalai lama).

Jun · Post by **Jun** » 2005-12-03 10:46

Eczema is very psychological. Others are less so.

helenClaire · Post by **helenClaire** » 2005-12-05 12:19

Jun wrote:Eczema is very psychological. Others are less so.

是啊是啊，如果数字不是这么反常地高，我也不会起了贪念。
我还是继续幻灭吧。

Knowing · Post by **Knowing** » 2005-12-05 12:51

听说有的药，多年研制，等上了临床，不如Placebo有效，真是欲哭无泪啊。

我好奇选临床实验的样本有没有限制？能不能挑长年生病，各种药，包括placebo 都没用的病人？还是必须'随机'? 有效率多少能通过？

Jun · Post by **Jun** » 2005-12-05 13:04

This is the issue with clinical trials. Nobody would knowingly and willingly take placebo for their disease. The placebo effect comes from the patient's conviction that the pills they take will work. That's why if a trial is controlled with placebo, it is also blinded (ie, you have no idea whether you're taking placebo or tested drug).

There have been attempts to "weed out" those who are sensitive to placebo effects in heavily psychological diseases. For example, I've seen antidepressant trials use a "lead-in" period. Essentially, every enrolled patient is put on sugar pills for 2-4 weeks at the beginning, and only those who do not become "well enough" (subject to arbitrary criteria) by the end of the lead-in period get to be further randomized to (blinded) placebo or drug treatment. The strategy doesn't always work, but it should help somewhat.

Never underestimate the power of wishful thinking.

lindamm · Post by **lindamm** » 2005-12-07 15:47

Eczema is very psychological? Usually we use steroids to treat eczema, Protopic is pretty effective, Elidel is less though. I did not realize it is a psychological disease. What are the reasons and what are the evidence to support?

helenClaire · Post by **helenClaire** » 2005-12-08 9:04

上面的数据是psorassis的。

Jun · Post by **Jun** » 2005-12-08 9:15

I cannot immediately provide evidence and data to support the statement about the psychological component of eczema. I have that piece of impression stuck in my head but cannot remember the sources.

Eczema can be effectively treated with corticosteroids, because the disease mechanism is tied with the hyperactive immune response. But psychological factors play a role in triggering flare-ups. Again, this is from some stuff floating in my head but I cannot cite the sources at the moment.

About psychological components, I heard yesterday on the news about a new study that came out that investigated the placebo effects in pain management. Not surprisingly, fibromyalgia is the class of chronic pain that's most responsive to placebo treatment.

It's kind of dangerous to cite psychological factors in somatic symptoms because it can be perceived as saying "the pain/itch/suffering is all in your head." It's true that the symptoms may be partially in the patient's head, but the suffering is every bit as real as symptoms generated from bones, muscles, tissues. And treating psychological factors alleviate the suffering is as legitimate as treating physiological factors like broken bones or overactive IgE.

lindamm · Post by **lindamm** » 2005-12-09 10:28

Jun讲得真是深入浅出

继续崇拜ing

还有个不是很相关的问题：像monoclonal antibody，如果是block了某些东西，是不是长期下去会对免疫系统有害处阿？比如anti-IgE (Xolair), anti-VEGF (Avastin) etc.

(汗一个，偶的问题果然是很外行的问法）

Jun · Post by **Jun** » 2005-12-09 10:53

这个问题一点也不外行啊。Monoclonal antibody把免疫系统发放出来的化学信号都搞掉了，会不会有严重后果，现在谁也不知道。只是知道在短期内它们比corticosteroids 副作用小，因为固醇类药除了影响免疫系统还影响很多其他系统。虽然临床研究对monoclonal antibody目前还没发现有很强烈的抑制免疫的作用，但是怀疑有增加感染(包括肺结核)和癌症的作用。不过因为时间不够久，至少短期内还看不出来。

silkworm · Post by **silkworm** » 2005-12-09 11:03

我在什么地方看到过，说这类monoclonal anti-IgE的specificity不好，不管是什么过敏源（花生过敏、哮喘etc），一律都抗。
我个人觉得，长期使用，恐怕够呛。

Jun · Post by **Jun** » 2005-12-09 11:15

现在monoclonal antibodies都是用在很严重的病上，类风湿关节炎，乳腺癌，ulcerative colitis，严重的全身psoriasis，等等，对这些病人来说是非用不可的药，至于有什么长期副作用也顾不得了。其实每个药都有副作用，例如治癌症的化学疗法增加将来得淋巴癌症的机会，但是救命的时候就管不了那么多了。

tiffany · Post by **tiffany** » 2005-12-09 11:20

silkworm wrote:我个人觉得，长期使用，恐怕够呛。

silkworm · Post by **silkworm** » 2005-12-09 11:24

白金为什么要露出大板儿牙？

JUN,为什么乳腺癌要治理免疫系统？

tiffany · Post by **tiffany** » 2005-12-09 11:28

长期使用，恐怕够呛，说的特喜剧效果。

silkworm · Post by **silkworm** » 2005-12-09 11:35

我也顺便问一个相关问题。
到美国以后，发现过敏很是要命。
比如我周围的中国朋友都说，在美国待上一阵子，第4-5年是个坎儿，不少人在这时开始对花粉草粉树粉过敏（比如我家先生），过了这个坎儿就没事儿了（比如我）。

又比如，为什么美国这边儿花生过敏的问题这么显著？以前在国内听都没听说的。我一对中国师姐师兄夫妇，在这边生了个大胖小子，增添辅食的时候，发现孩子过敏---过敏源是wheat products。所以他们儿子连吃菜必须单做没有酱油的，在幼儿园阿姨没看住抢了小朋友的wheat cracker就要吃药。这也是以前没听说过的。

然后是有一次看见一个报道，说研究（质量我们暂且不细究哈）显示：toddlers家里有养猫狗宠物的，长大以后有过敏或发哮喘的几率下降。

我就怀疑，是不是环境太过清洁，才导致免疫系统过分反应，以至于过敏。“不干不净吃了没病”，也许有一定道理？！

Jun · Post by **Jun** » 2005-12-09 11:48

Apparently there have been a number of new antibodies approved for various cancers in recent years, not just Herceptin against breast cancers.

Monoclonal antibodies are "manufactured" to recognize antigens on cancer cells, bind themselves to the tumor, and induce the body's immune system to destroy the tumor cells.

A different kind of monoclonal antibodies are designed to bind to cytokines and immunoglobulins and thus block their activity. They are effective in autoimmune diseases.

tiffany · Post by **tiffany** » 2005-12-09 11:49

４啊，我也这么觉得的。说实在的。
刚来的时候据说因为过敏源比较多：国内植被不一样，免疫系统没见过这些花粉等等，挺容易闹过敏的。呆长了开始闹，我觉得就是太干净了，免疫系统闲的。今年春天我有点儿轻度过敏反应－－－老觉得脸上痒痒的，眼睛也是。
哦，说道这个nuts过敏，好像不是终身过敏的。可以过两年测一测，免疫系统反应不太一样。

lindamm · Post by **lindamm** » 2005-12-09 11:52

谢谢Jun和蚕宝答疑.

乳腺癌是指对Herceptin, 据说Her-2 gene overexpression是造成乳腺癌成因之一, 有25-30%那么多. 而且目前还扩展到早期的乳腺癌治疗去了.

象Jun所说的, 就不应该再非严重的病例中用.

lindamm · Post by **lindamm** » 2005-12-09 12:01

是不是和美国用农药太多, 清洁过分也有关呢(比如夏天连个蚊子都没有)? 偶想起Merck的Singulair, 治过敏性鼻炎的, 在美国卖了2bio, rest of the world 1bio都不到, 这个是不太正常的.

偶没做过统计, 也没看过详细的资料. 但很少听在欧洲的同学抱怨过敏什么的, 在美国的就象蚕说的那样, 3-5年其间大家纷纷就开始过敏.

silkworm · Post by **silkworm** » 2005-12-09 12:05

哦，原来乳腺癌用抗体是这么回事儿。谢谢答疑。

我理解得对么？
前面lindamm所说的那类anti-IgE的monoclonal antibody，跟治乳腺癌的monoclonal antibod，好象不是一类。两者虽然都是manufactured (recombinant)，但前者是抗体结合IgE，降低自由IgE浓度，减弱下游免疫反应。而后者是抗体有的放矢地结合抗原antigen，将癌细胞致死。

Jun · Post by **Jun** » 2005-12-09 12:50

monoclonal antibody 有很多种，它们的目标也有很多，有些是免疫球蛋白(不仅是IgE)，有些是化学信号(cytokines, 例如tumor necrosis factor, interleukins)，有些是tumor antigen，反正你要它攻击谁，就照着目标的特征antigen (eg, cell-surface proteins 或蛋白质上的碳水化合物分支) 来反着造antibody。所以用处很多，还没挖掘尽。

洛洛 · Post by 洛洛 » 2005-12-09 14:04

lindamm wrote:谢谢Jun和蚕宝答疑.

乳腺癌是指对Herceptin, 据说Her-2 gene overexpression是造成乳腺癌成因之一, 有25-30%那么多. 而且目前还扩展到早期的乳腺癌治疗去了.

象Jun所说的, 就不应该再非严重的病例中用.

前两天我看cbs news，又有医生研究发现，女用的脱毛剂（类似veets那种）也会造成breast cancer的高发率,和FDA的解释不一样。