Delirium is an acute disturbance in attention, awareness, and cognition that fluctuates over time [1]. Delirium occurs in 21% of patients after hip fracture surgery [2], 48% of patients during follow-up in long-term care (LTC) facilities [3], and 24.6% of patients on admission to acute hospitals [4]. Among hospitalized older adults with dementia, the prevalence of delirium is 48.9% [5]. Although these proportions differ by population and assessment period, delirium is common across care settings. Delirium is associated with cognitive decline [6], increased mortality, longer hospital stays, institutionalization, higher health care costs, and increased caregiver burden [7-9]. Early recognition is particularly important for older patients with cognitive impairment, whose cognitive and functional difficulties may complicate delirium assessment and care.

Early identification of patients at risk is important for delirium prevention and management [5,7]. Delirium risk is related to both underlying vulnerability and acute clinical stressors [10]. Assessment therefore needs to consider cognitive status, physical illness, medication use, and daily care needs. Multicomponent nonpharmacological interventions can help prevent delirium in hospitalized patients outside intensive care units (ICUs) [11]. However, evidence for preventive interventions in institutional LTC remains limited [12]. Differences in patient characteristics and care needs require attention when applying findings from acute hospitals to LTC hospitals. Identifying factors associated with delirium in LTC hospitals can help nurses assess patients at risk and develop appropriate preventive care.

Most delirium research has focused on patients in ICUs, acute hospitals, and surgical settings. Delirium is also common among patients with dementia in LTC hospitals [3]. Patients with dementia who experience delirium have longer hospital stays and poorer outcomes than those without delirium [5,13]. Changes in attention, cognition, and behavior may be difficult to distinguish from existing dementia symptoms, making comparison with the patient’s usual condition important [13]. In residential care, delirium prevalence ranges from 1% to 70.3%, with the highest proportion in a population with dementia. Cognitive impairment and dementia are consistently associated with delirium in these settings [14]. However, the wide variation in patient populations and assessment periods limits direct comparisons across studies.

Patients with mild cognitive impairment (MCI) also require attention in delirium care. MCI is associated with progression to dementia, although the rate varies by population, diagnostic criteria, and follow-up period [15]. Physical inactivity, smoking, diabetes, obesity, and hypertension are modifiable factors associated with dementia [16]. Dementia also places a substantial financial burden on care in South Korea [17]. These clinical and care burdens support the need to address cognitive health in patients with MCI as well as those with dementia. However, the clinical and care-related factors associated with delirium in patients with MCI in LTC hospitals remain unclear. Examining both groups may help identify their delirium care needs.

Older patients in LTC hospitals often have chronic illnesses and cognitive impairment that require ongoing nursing care. Nurses observe changes in patients’ condition during daily care and have an important role in recognizing possible delirium. Information on delirium occurrence, motor subtypes, and associated factors can help nurses identify patients who need further assessment. Findings from patients with dementia and those with MCI may also help guide care according to cognitive status. However, evidence specific to these patients in LTC hospitals is needed to support delirium assessment and management.

This study examined delirium occurrence, motor subtypes, and associated factors among patients with dementia or MCI in LTC hospitals. Factors associated with delirium were examined in all participants and in the dementia and MCI groups. The findings may help guide nursing assessment and delirium care for patients with cognitive impairment in LTC hospitals.

This study examined delirium occurrence and associated factors among patients with dementia or MCI in LTC hospitals. Delirium was identified in 38.7% (55/142) of patients, and hypoactive delirium was the most common subtype. Female sex, immobility, and analgesic use were positively associated with delirium overall, whereas infection was inversely associated with delirium.

Delirium was identified in 38.7% of patients, compared with 48% in the Korean LTC hospital study by Moon and Park [3], which used the same assessment instrument. Their study included patients with and without dementia and assessed delirium for 3 months, whereas our study focused on patients with dementia or MCI over 4 weeks. Differences in populations and assessment periods also contribute to the wide range of prevalence estimates in residential care (1%-70.3%) [14]. Despite these differences, delirium affected more than one-third of our participants, supporting the need for regular assessment in patients receiving care for cognitive impairment.

Hypoactive delirium was the most common subtype overall (33/55, 60%) and in patients with dementia (27/41, 65.9%), whereas hyperactive delirium was most common in patients with MCI (7/14, 50%). The predominance of hypoactive delirium is consistent with the ICU findings of la Cour et al [21], where this subtype accounted for approximately 50.3% of cases. However, mixed delirium predominated in the LTC hospital study by Moon and Park [3]. Ghezzi et al [22] found poorer cognition in patients with hypoactive than hyperactive delirium, although the effect size was small. These findings highlight the relevance of cognitive status when interpreting motor patterns. Hypoactive delirium may be overlooked when patients appear quiet [9], making observation of changes in activity and attention important [23]. In patients with dementia, nurses need to compare these changes with usual behavior. In patients with MCI, both increased and reduced activity require attention, as hypoactive delirium still accounted for 42.9% (6/14) of patients with MCI who developed delirium.

Female sex, immobility, and analgesic use remained associated with delirium after adjustment for age, CCI score, and K-MMSE score. Patients with dementia may have difficulty expressing pain [24,25], and pain has been associated with delirium in this population [26]. A meta-analysis also identified an association between pain and delirium among older hospital inpatients, although most included studies involved surgical patients [27]. Our finding for analgesic use therefore needs to be interpreted alongside pain and the reasons for treatment. Mobility also warrants attention, as physical dysfunction has been linked to delirium [28], and immobility was associated with delirium in the univariable analysis of older patients undergoing cholecystectomy [29]. Together, these findings support assessing pain in ways suited to patients’ communication abilities and considering mobility, pain relief, and changes in attention during daily care.

Infection was inversely associated with delirium in our study. Associations between systemic infection and delirium in residential care have also been inconsistent or nonsignificant [14]. Our infection variable included physician diagnosis, laboratory evidence, or antibiotic use, and its timing relative to delirium was unknown. The inverse association should therefore not be interpreted as a protective effect of infection.

Diaper use was associated with delirium in the MCI group, with use recorded in 64.3% (9/14) of patients with delirium and 7.1% (2/28) without delirium. The association remained after adjustment for sex, but the wide CI indicates limited precision. Diaper use may reflect a need for assistance with continence, mobility, or toileting, although these needs were not established by our data. Clinically, the finding draws attention to the circumstances of diaper use and the patient’s functional status. Documenting the reasons for diaper use and changes in toileting ability alongside cognitive and behavioral changes may help nurses assess these care needs. Future studies should examine these factors before delirium develops to clarify the observed association.

Delirium was identified in one-third of patients with MCI, indicating a need for assessment, as well as in patients with dementia. Sabbagh et al [30] emphasized linking MCI recognition with further assessment and appropriate care in primary care. In acute care hospitals, gaps remain in cognitive assessment, documentation, and communication with patients and caregivers [31]. These findings are relevant to continuity of cognitive care in LTC hospitals, where nurses can document usual cognitive and functional status, share changes during handover, and consult familiar caregivers when establishing the patient’s baseline. Regular delirium assessment, together with attention to mobility, pain, and toileting needs, provides a focus for nursing care. The effectiveness of preventive care based on these findings requires evaluation in LTC hospitals, where intervention evidence remains limited [12].

This study has several limitations. First, data were collected during the COVID-19 pandemic, when masks and changes in the care environment and social contact may have affected delirium assessment and occurrence. Assessment completeness was not quantified, and formal interrater reliability was not evaluated during data collection. Symptoms of dementia and delirium can also overlap, complicating assessment in patients with moderate to severe dementia despite training [32]. Second, the timing of clinical conditions and care practices relative to delirium was unknown, precluding causal interpretation. Details of sedative use and the interval and type of prior surgery were unavailable. Third, the sample size was calculated for multiple linear regression rather than the logistic models used. The small cognitive groups, particularly the MCI group, limited estimate precision. Fourth, pain assessment included medication use, and infection assessment included antibiotic use, limiting the separation of symptoms from treatment-related associations. We did not adjust for multiple comparisons. Finally, recruitment from 2 LTC hospitals limits generalizability to other settings and patients without cognitive impairment. Larger longitudinal studies are needed to confirm these associations.

Delirium was common among patients with dementia or MCI in LTC hospitals, and hypoactive delirium was the most common subtype overall. Female sex, immobility, and analgesic use were positively associated with delirium, whereas infection was inversely associated. These findings support regular delirium assessment, with attention to mobility and pain-related care needs. Further longitudinal studies are needed to clarify these associations and the findings in each cognitive group.