Specificity placebo

The HPLC method for which data are given had previously been shown to be linear over a wide range of concentrations what was of interest here was whether acceptable linearity and accuracy would be obtained over a relatively narrow concentration range around the nominal concentration in the product the specification limits were 90-110% of nominal. Three concentrations were chosen and three repeat determinations were carried out at each. Two different samples were prepared at each concentration, namely an aqueous calibration solution and a spiked placebo. All samples were worked up according to the method and appropriate aliquots were injected. The area counts are given in the second, respectively the fifth column of Table 4.42. 

Nielsen L. Johnsen CR, Mosbech H, Poulsen LK. Mailing HJ Antihistamine premedication in specific cluster immunotherapy a double-blind, placebo-controlled study J Allergy Clin Immunol 1996 97 1207-1213. 

The severity of the neurological deficit at the time of stroke onset is a major predictor of stroke outcome. In an analysis of the placebo-treated patients in the National Institute of Neurological Disorders and Stroke (NINDS) recombinant tissue-plasminogen activator (rt-PA) study, the best acute predictor of a poor outcome at 1 year was an National Institute of Health Stroke Scale (NIHSS) score >17 for patients over 70 years. These criteria had a high specificity (98%), but sensitivity was only 31%. The low sensitivity of the acute NIHSS score alone in predicting... 

It is important that future studies of antioxidant treatment in patients with specific disorders should be well designed (randomized, double-blind, placebo-controlled) prospective studies that utilize the most up-to-date methodology to assess free-radical activity. 

There is usually no need to supplement with specific vitamins. Patients should be encouraged to eat a well balanced diet and should also take a multivitamin and mineral supplement. Some clinicians recommend vitamins C and E for their antioxidant properties however, no significant improvements have been shown compared to placebo. Encourage patients to eat a diet rich in vitamin C and E (i.e., bright colored fruits and vegetables, nuts, and whole grains). Metabolism of levodopa may cause elevated homocysteine concentrations that... 

Phase II investigates the compound s efficacy and safety in controlled clinical trials for a specific therapeutic indication. To eliminate as many competing factors as possible, Phase II trials are narrowly controlled. They are characterized as small—several hundred subjects with the indicated disease or symptoms—and are closely monitored. The control may be either a placebo study arm or an active control arm. The endpoint measured may be the clinical outcome of interest or a surrogate. Phase II trials may last for several months or even several years. Early pilot trials to evaluate safety and efficacy are called Phase Ila. Later trials, called Phase lib, are important tests of the compound s efficacy. These trials may constitute the pivotal trials used to establish the drug s safety and efficacy. At least one pivotal trial (most frequently a large, randomized Phase III study) is done. Only about one third of compounds entered into Phase II will begin Phase III studies [61],... 

I suppose that some ingenious minds will be able to find a way of accommodating the chemical-balance hypothesis to these data, but I suspect that the accommodation will require convoluted circumventions, like those used by the Flat Earth Society in their efforts to maintain their defunct theory in the face of photographic evidence from space. If depression can be equally affected by drugs that increase serotonin, drugs that decrease it and drugs that do not affect it at all, then the benefits of these drugs cannot be due to their specific chemical activity. And if the therapeutic benefits of antidepressants are not due to their chemical composition, then the widely proffered chemical-imbalance theory of depression is without foundation. It is an accident of history produced serendipitously by the placebo effect. 

When our most recent - and most definitive - meta-analysis was published, the headlines in many newspapers blazoned that antidepressants don t work .1 The Daily Telegraph headline phrased it more specifically, clarifying that antidepressants are no better than dummy pills ,2 but even this headline was not entirely accurate. What our analyses actually showed was that antidepressants work statistically better than placebos, but that this statistical difference was not clinically meaningful. It was too small a difference to be of much importance in the life of a severely depressed person. 

Although the therapeutic relationship and positive emotions are clearly important, there are many instances of the placebo effect that they cannot explain. They cannot, for example, explain the effect of placebos in research settings in which students or other healthy volunteers have been asked to participate in return for money or course credit. In these studies there is no therapeutic relationship. Most importantly, emotions cannot explain the specificity of the placebo effect. 

If you look in the medical literature, you will often see the term placebo defined as a non-specific treatment. What does it mean to say that a treatment is not specific It could mean that the treatment is effective for many different disorders, rather than for only one particular condition. In this sense, placebos are indeed non-specific. Besides depression, placebos have been shown to affect anxiety, pain, ulcers, irritable bowel syndrome, Parkinson s disease, angina, autoimmune diseases, Alzheimer s disease, rheumatoid arthritis, asthma, gastric function, sexual dysfunction and skin conditions. We know this from the thousands of studies in which placebos have been used as control conditions, against which the effects of medication have been evaluated, and from studies that were specifically designed to assess the placebo effect. 

Although placebo effects are generally referred to as nonspecific, there is also a sense in which they are very specific. The effect of the placebo is specific to the beliefs that people have about the substance they are ingesting. Placebo morphine, for example, reduces pain, whereas placebo antidepressants reduce depression. Even the side effects that people report when given a placebo tend to be the same side effects that are produced by the real drug.12 In other words, the effect of a placebo is specific to the effect that the person expects it to have. When given placebo stimulants like decaffeinated coffee (presented as regular coffee), people feel more alert, and their heart rate and... 

---