Association of bipolar disorder with new-onset delirium among critically ill patients

Delirium is a frequent and serious neuropsychiatric complication among intensive care unit (ICU) patients. Individuals with bipolar disorder, a chronic psychiatric illness associated with increased neural vulnerability, may be at heightened risk for developing delirium during critical illness. This study examined whether bipolar disorder independently raises the risk of new-onset delirium in ICU patients.

We conducted a propensity score-matched cohort study utilizing the Medical Information Mart for Intensive Care (MIMIC)-IV database. Adults aged 18 years or older admitted to the ICU were included. Patients with prior or pre-existing delirium or missing assessments were excluded. The main outcome was new-onset delirium, assessed by the Confusion Assessment Method for the ICU (CAM-ICU).

A total of 49,213 patients were included (mean [SD] age, 65.1 [16.9] years; 21,515 [43.7 %] female). After 1:3 propensity score matching, 4796 patients remained (mean [SD] age, 54.5 [18.0] years; 2562 [53.4 %] female). New-onset delirium occurred in 476 of 1199 patients (39.7 %) with bipolar disorder and in 1097 of 3597 patients (30.5 %) without bipolar disorder (P < 0.001), yielding an absolute risk difference of 9.2 %. In Cox regression analysis, bipolar disorder was associated with an increased risk of delirium (hazard ratio, 1.41; 95 % CI, 1.27-1.57; P < 0.001).

Potentially unmeasured confounding and limited generalizability may affect validity.

Bipolar disorder is independently associated with higher ICU delirium risk among critically ill adults. These findings highlight the need for targeted delirium prevention strategies in patients with bipolar disorder and warrant further investigation into the underlying mechanisms.