Association between nicotine-dependent patients and delirium in intensive care units: a retrospective cohort study...

Although nicotine use is a significant and potentially modifiable risk factor for delirium in ICU patients, evidence on the association between nicotine dependence (ND) and ICU delirium remains limited.

This retrospective cohort study used the MIMIC-IV v3.1 database and included adult patients admitted to the ICU for ≥ 24 h with documented delirium assessments. Patients with schizophrenia, dementia, depression, alcohol abuse, or cerebrovascular disease were excluded. Patients were classified into ND and non-ND groups. The primary outcome was ICU delirium incidence; secondary outcomes included in-hospital mortality, ICU mortality, hospital length of stay, and ICU length of stay. Confounders were balanced using 1:1 propensity score matching (PSM). Cox regression and competing risk models were used to assess the association between ND and delirium. Subgroup and sensitivity analyses were performed, and the effects of ICD coding versions and NRT treatment were also evaluated.

A total of 24,043 patients were included, with 2,662 (11.07%) in the ND group. After PSM, baseline characteristics were balanced. The ND group had a significantly higher incidence of delirium than the non-ND group (30.8% vs. 27.2%, P = 0.004), with no significant differences in mortality or length of stay. Multivariate Cox and competing risk models confirmed that ND was independently associated with increased ICU delirium risk. Findings remained consistent in PSM and sensitivity analyses.

Nicotine dependence significantly increases the risk of ICU delirium. These results highlight the need for targeted risk assessment and intervention strategies in ND patients admitted to the ICU.