Placebo controlled trials of pharmacological treatments are needed

EDITOR—In reviewing the management of delirium, Meagher asserts that antipsychotic drugs are effective in patients with delirium.1 There is, however, little evidence to support this assertion. There are no placebo controlled trials of antipsychotic drugs in patients with delirium. One trial compared antipsychotic drugs with benzodiazepines and found that antipsychotic drugs were superior, but, given that it is widely acknowledged that benzodiazepines may worsen delirium, this result hardly constitutes evidence of efficacy.2 Most clinicians have gained the impression that antipsychotic drugs speed recovery in delirium, but their anecdotal observations must be doubted. Most episodes of delirium last only several days and will improve when the patient's underlying medical condition resolves. In practice, medical management is always instituted simultaneously with prescription of antipsychotic drugs. As a consequence, it would be very difficult for clinicians to isolate the relative effect of an antipsychotic drug on the resolution of delirium. Uncontrolled trials suggesting efficacy will present the same problems.

Delirium often manifests with hallucinations, delusions, or thought disorder. In other psychiatric disorders, such as schizophrenia, these symptoms are improved by antipsychotic drugs, so it is reasonable to postulate that these drugs may also help in cases of delirium. But this hypothesis may be invalid. Treatments for asthma will not necessarily help pneumonia, although both illnesses cause shortness of breath. With so little evidence to support the use of antipsychotic drugs in patients with delirium, management strategies invoking them must be extremely cautious. Meagher proposes a strategy for the management of severe behavioural disturbance in patients with delirium that could quickly lead to doses of haloperidol of up to 100 mg per day. Doses this high may be associated with anticholinergic toxicity and akathisia—a sense of inner restlessness—that may worsen agitation rather than quell it. Such doses also entail an increased risk …