Placebo-controlled trials in depression are scientifically necessary, ethical and feasible. As mentioned in a recent post about antidepressants for adolescents I am a great fan of placebo controlled trials, also in depression.
The best clinical trial is a placebo controlled trial, because:
- The response to placebo can vary considerably form around 10 to 50%.On average 30% of patients respond to placebo
- The proportion of patients who respond to placebo has increased with 7% per decade. This effect is mainly caused by the method of patient recruitment and the inclusion of patients with less severe forms of depression
- According to several studies,no difference in rates of suicide and attempted suicide was found in placebo controlled trials compared to the patients on antidepressants in those trials
- In a placebo controlled trial it is easier to distinguish between adverse reaction to the drug and disease symptoms
- Smaller sample sizes are required.They expose fewer patients to ineffective or potentially harmful drugs
- Studycosts are reduced
- New drugs become available sooner to patients if efficacious
Only placebo-controlled trials can give unambiguous evidence of efficacy and if future antidepressants were only tested against standard treatment, half of the studies would yield invalid (false positive or false negative)results.
The response of a patient to drug treatment is not only affected by the drug itself but also by:
- features of the illness.For instance in bulimia most patients also suffer from personality disorder which reponds to the structured visits and attention of the researcher. Not per se to the antidepressant
- The personality of the patient.
- The doctor-patient relationship. If you like your doctor you wouldn't want to disappoint him of her.
- The setting of the treatment. Inpatients are different from outpatients. Depressed inpatients aremore often suicidal and or psychotically depressed
These confounding effects can only be reduced by a controlled trial, preferably a placebo controlled trial.
Adam, D., Kasper, .S., MÃ¶ller, H., Singer, E.A. (2005). Placeboâ€“controlled trials in major depression
are necessary and ethically justifiable. European Archives of Psychiatry and Clinical Neuroscience, 255(4), 258-260. DOI: 10.1007/s00406-004-0555-5