View Full Version : Placebo contriols ?
03-12-2002, 12:36 AM
I am completely lost on the debate over placebo controls ... first of all, what are placebo controls and secondly, what is the ethical dikemma surrounding them?
Please help !!!!
not rex morgan
03-12-2002, 02:34 AM
The proper scientific method dictates that controls need to be used. For example, in molecular biology, if you want to know what molecule X does, you have to express it in cells, but at the same time, you have to grow up cells that haven't been transfected with the gene for the molecule, to make sure the effect you get is not an effect of the medium you grow it up in. The equivalent to this control in clinical trials is to have a placebo (essentially, sugar pills). So, when something is in clinical trial, half the people in the study are given the drug, and the other half are given a placebo. A blind placebo trial is when the patient does not know whether or not he or she is getting the possibly life-saving drug, or something else. A double blind trial is when neither the physician or the patient know what the patient is getting. The major arguement for placebos is that this is the only way you can know that the drug works...scientific integrity. The major arguement against is that by the time drugs get to phase III testing (ie. clinical trials in humans), the drug has already been implicated by animal testing to be safe and beneficial. By possibly exposing patients to placebo, you are not providing them with a possibly life-saving drug.
Hope this helps you.
03-12-2002, 05:45 AM
When one conducts true "experimental" research (where you manipulate conditions in some way as opposed to observational research where you merely observe without interfering with things), it is important to be able to conclude, if any effect that you observe (e.g., patients get better with procedure x) it is due to your treatment (i.e., experimental manipulation x) and not some other confounded variable (i.e., some condition which exists at the same time as your supposed cure, for example, which is actually responsible for the observed effect (i.e., the patnients get better). The way to do this is to equate all conditions for all patients except for a single factor (i.e., your treatment x). Placebos help the experimenter do exactly this. Placebos take many different forms...one classic example is a sugar pill. The following is a scenario where a sugar pill might be used as a placebo for experimental purposes:
Researcher X had developed a new pill to supposedly treat bacterial infection Y. The researcher works with a clinician who identifies people in his clinic with bacterial infection Y. The researcher, without the physician's or patient's knowledge (assuming the patients have given consent to be part of a study and given consent to potentially receive a placebo treatment) and randomly assigns patients/study participants to one of two groups...placebo vs. treatment. This type of study would be labelled a double-blind (neither clinician nor patient knows which group they are in) between-subject's design (i.e., one group of patients gets treatment and one group does not). Two types of pills, would be created...the pill containing the active ingredient (i.e., the miracle cure) and another pill with all the same ingredients except for the active ingredient...the placebo). The placebo pill would be completely indistinguishable from the pill with active ingredient...in all respects...colour, shape, texture, labelling, etc. One group gets the placebo and one group gets the pill with active ingredient. At the end of the 'treatment period', which would be the same for all participants, presence/absence of said bacterial infection would be measured and recorded. If the treatment drug worked then the group receiving the placebo should still have the bacterial infection and the group receiving treatment should not (ideally) or should have reliably less of the bacterial infection than the group not receiving treatment...the placebo group. In this way everything has been equated for both groups...how the clinician diagnosed presence of the bacteria...the instructions given to patients...the length of treatment...all inactive ingredients in the pill, etc. The single factor that was different between the groups was active ingredient therefore any change in level of bacterial infection can be causally attributed to the active ingredient and not on how the clinician treated the patient, how long the treatment period was or some other ingredient in the pill.
The obvious ethical issue in this type of research is that the patients in the placebo group with a known medical problem are being given a fake/placebo cure and will therefore suffer longer than they would have had to if they had had a proper treatment regimen.
Sugar pills are only one type of experimental control, however...there are many different types...in a study on brain surgery treatments, for example, one group might have all surgery done up until the point, for example, that the corpus callosum is cut, whereas the second group might have all those surgical procedures plus the cutting of the corpus callosum...this might be to ensure that behavioural improvement after surgery was due to the cutting of the corpus callosum and not because of some other surgical procedure leading up to the cutting of the corpus callosum. For a more thorough description of control groups and placebos I would suggest picking up an introductory level psychology book on "Experimental Design." I would also be more than happy to answer any further questions you have.
vBulletin® v3.6.5, Copyright ©2000-2013, Jelsoft Enterprises Ltd.