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Table 1 A table displaying the definitions of phenotype, subphenotype, endotype, and treatable traits, as described by Lötvall et al. [1]

From: Phenotypes and subphenotypes of delirium: a review of current categorisations and suggestions for progression

Term

Definition

Potential application to delirium

Phenotype

A set of clinical features in a group of patients who share a common syndrome or condition.

Altered cognition

Inattention

Altered awareness

Disorientation

Subphenotype

A set of features in a group of patients who share a phenotype. Includes shared risk factors, traits, diagnostic features, expression markers, mortality risk, or treatment response—which distinguishes the group from other patients with the same phenotype.

Clinical

Shared risk quantification

Shared precipitants

Specific symptoms, e.g. inattention, agitation

Delirium duration

Diagnostic features

Defined by pathophysiology

Prominent mechanism

Inflammatory/non-inflammatory

Melatonin levels

Neurotransmitter presence

Network connectivity extent

Presence of oxidative stress

Endotype

A distinct biological mechanism of disease which is often associated with an anticipated clinical course, shared by a patient subgroup.

Associations between biological putative pathways of delirium and the clinical symptoms which occur as a result

Treatable traits

Subgroup characteristics which may be successfully targeted by an intervention.

Decisions and development of the best course of action for treatment-

Treating symptoms

Treating the mechanisms which express the symptoms

A combination of both

  1. The potential applications of these definitions to delirium are listed, where the phenotype describes the most common clinical domains. Potential subphenotyping methods may be divided by clinical features and by pathophysiological hypotheses, and the endotype is a hybrid between these. Future treatable traits will be decided once the most effective methods are determined. It is important to note that this is a suggested framework for categorisation