Table 1.

The canons of therapy as a set of specific rules to guide clinicians’ approaches to treatment, and their application in example cases involving delirium.

Canon	Description	Clinical example
Restoration	The goal of all treatment is to restore the patient, as much as possible, to homeostatic equilibrium; restoration can be complete, as with cure, or partial, as with relief of symptoms.	In the case of Mrs. R, a 68-year-old woman with colorectal cancer metastatic to the lung, treatment of her pulmonary embolism and her symptoms related to delirium aimed at partial restoration so that she could enjoy visits from family members and a chaplain.
Means-end proportionality	Every treatment should be well-fitted to the intended goal or end; in contrast, end-end proportionality involves weighing the expected benefits and burdens of a treatment.	For Mr. M, a 62-year-old man with liver cirrhosis, treatment of his hepatic encephalopathy without use of antipsychotics aimed at improving his mental status without abruptly stopping his “pleasant” hallucinations that may have had existential or religious meaning.
Discretion	An awareness of the limits of medicine—those of the craft itself, its evidence base, and clinicians’ own expertise—should guide all treatment decisions.	In the case of Mr. D, a 77-year-old man with Parkinson’s disease-related dementia, available evidence did not support the use of clinically assisted hydration to prevent delirium; however, given his pattern of failure to thrive leading to delirium, Mr. D opted for feeding tube placement and its use at home.
Parsimony	Only as much therapeutic force as is necessary should be used to achieve the therapeutic goal; this is justified primarily by concern for the patient’s well-being—“do no harm.”	For Ms. P, a 74-year-old woman with breast cancer metastatic to bone and liver, she wanted “to take the edge off” her symptoms but to remain alert and interactive; she was prescribed modest doses of medications for pain and anxiety, with due consideration of her reduced kidney and liver function.