5 - Delirium: what causes it? Risk factors

Summary

Introduction

Delirium is serious. A good clinician is keen to reduce the number of patients who develop this syndrome. But what causes delirium? Are some patients more susceptible than others? Should we routinely screen for delirium? If yes, which group of patients?

Good questions but we don't have all the answers… just a few which we will explore in this chapter.

Considering that the pathophysiology is still unclear, it is not surprising that studies to establish what puts a patient more at risk of developing delirium come up with a number of different answers. If we understood the mechanisms, then we would be able to explore with greater accuracy the predisposing and precipitating factors. Risk factors cover a wide range of disparate patient characteristics and illnesses, often related to the various mechanistic hypotheses that include inflammation, lack of oxygen supply, neurotransmitter imbalance caused by drugs, ageing process, or all the above… No less than 61 risk factors were identified out of 27 prospective studies including 1365 patients with delirium.

We know that critically ill patients are particularly at risk of delirium and we need to screen all critically ill patients regularly, at least daily. Risk factors can be controlled (to some extent) and delirium can be managed (sometimes) but only if we know it is present.