Review question
We reviewed the evidence for non-pharmacological (non-medication-based) approaches to prevent delirium in adults in hospital, not including those treated in intensive care units (ICU, specialised wards for the care of critically ill patients).
Background
Delirium is an important illness which is common among adults, especially older adults who are in hospital. It is sometimes referred to as an 'acute confusional state'. Typically, a person with delirium has sudden onset of confusion, which fluctuates, and often includes impaired concentration, memory and thinking skills; reduced awareness of surroundings; drowsiness or agitation and restlessness; and hallucinations, which are usually visual (seeing things which are not really there). It can be distressing for the individual with delirium and their family. It is also associated with increased risks of complications, such as dying in hospital, having a longer hospital stay, and requiring more care after discharge. Increasingly, there is evidence that delirium is associated with an increased risk of permanent worsening of memory and thinking skills, including development or worsening of dementia.
Non-pharmacological approaches are approaches which do not use medications, but which focus on other aspects of care. They are already recognised as important in reducing the risk of delirium, particularly multicomponent interventions which target several of the common risk factors for delirium. It is not known which components of these complex interventions are most important in preventing delirium and this was something we wanted to find out.
Study characteristics
We searched up to 16 September 2020 for reports of studies in which people in hospital were randomly allocated to a non-pharmacological intervention intended to prevent delirium or to usual hospital care. We found 22 studies with 5718 participants. Fourteen of the studies were of multicomponent approaches; two studies looked at different cut-offs for giving a blood transfusion after an orthopaedic operation; the remaining six studies all considered different approaches.
Key findings
Multicomponent approaches probably reduce occurrence of delirium by 43% compared to usual hospital care. This means that two in five cases of delirium in adults in hospital wards (other than ICU) can be prevented by multicomponent, non-pharmacological approaches. These interventions may also reduce the length of time people stay in hospital and, if delirium does occur, they may reduce the duration of the delirium episode by about a day. However, these approaches may have little or no effect on the risk of dying in hospital. The studies did not investigate the effect of multicomponent interventions on the development or worsening of dementia. There was little information about whether the interventions had any harmful effects.
Using a new statistical technique, we found that the following components within each intervention were most important for preventing delirium: (a) trying to keep people well-oriented to their surroundings and making their surroundings more familiar, (b) providing stimulation to memory and thinking skills, and (c) trying to improve sleep (through sleep hygiene measures). We could not be so certain about the effect of other components, largely because not enough evidence was available. More research is needed comparing the specific components included in multicomponent interventions to help determine the most effective and efficient ways to prevent delirium.
The evidence for other, single-component, non-pharmacological interventions was very limited.
Certainty of the evidence
There were some limitations in the studies which may affect the results. In many included studies the people in the study and sometimes researchers were aware of who was and was not receiving the intervention.
There was very little information about people living with dementia, who are at greater risk of experiencing delirium.
External funding
Funding to support researchers to undertake this review was received from the National Institute for Health Research (Incentive Award 130725) and Medical Research Scotland (Vacation Scholarship).
There is moderate-certainty evidence regarding the benefit of multicomponent non-pharmacological interventions for the prevention of delirium in hospitalised adults, estimated to reduce incidence by 43% compared to usual care. We found no evidence of an effect on mortality. There is emerging evidence that these interventions may reduce hospital length of stay, with a trend towards reduced delirium duration, although the effect on delirium severity remains uncertain. Further research should focus on implementation and detailed analysis of the components of the interventions to support more effective, tailored practice recommendations.
Delirium is an acute neuropsychological disorder that is common in hospitalised patients. It can be distressing to patients and carers and it is associated with serious adverse outcomes. Treatment options for established delirium are limited and so prevention of delirium is desirable. Non-pharmacological interventions are thought to be important in delirium prevention.
To assess the effectiveness of non-pharmacological interventions designed to prevent delirium in hospitalised patients outside intensive care units (ICU).
We searched ALOIS, the specialised register of the Cochrane Dementia and Cognitive Improvement Group, with additional searches conducted in MEDLINE, Embase, PsycINFO, CINAHL, LILACS, Web of Science Core Collection, ClinicalTrials.gov and the World Health Organization Portal/ICTRP to 16 September 2020. There were no language or date restrictions applied to the electronic searches, and no methodological filters were used to restrict the search.
We included randomised controlled trials (RCTs) of single and multicomponent non-pharmacological interventions for preventing delirium in hospitalised adults cared for outside intensive care or high dependency settings. We only included non-pharmacological interventions which were designed and implemented to prevent delirium.
Two review authors independently examined titles and abstracts identified by the search for eligibility and extracted data from full-text articles. Any disagreements on eligibility and inclusion were resolved by consensus. We used standard Cochrane methodological procedures. The primary outcomes were: incidence of delirium; inpatient and later mortality; and new diagnosis of dementia. We included secondary and adverse outcomes as pre-specified in the review protocol. We used risk ratios (RRs) as measures of treatment effect for dichotomous outcomes and between-group mean differences for continuous outcomes. The certainty of the evidence was assessed using GRADE. A complementary exploratory analysis was undertaker using a Bayesian component network meta-analysis fixed-effect model to evaluate the comparative effectiveness of the individual components of multicomponent interventions and describe which components were most strongly associated with reducing the incidence of delirium.
We included 22 RCTs that recruited a total of 5718 adult participants. Fourteen trials compared a multicomponent delirium prevention intervention with usual care. Two trials compared liberal and restrictive blood transfusion thresholds. The remaining six trials each investigated a different non-pharmacological intervention. Incidence of delirium was reported in all studies.
Using the Cochrane risk of bias tool, we identified risks of bias in all included trials. All were at high risk of performance bias as participants and personnel were not blinded to the interventions. Nine trials were at high risk of detection bias due to lack of blinding of outcome assessors and three more were at unclear risk in this domain.
Pooled data showed that multi-component non-pharmacological interventions probably reduce the incidence of delirium compared to usual care (10.5% incidence in the intervention group, compared to 18.4% in the control group, risk ratio (RR) 0.57, 95% confidence interval (CI) 0.46 to 0.71, I2 = 39%; 14 studies; 3693 participants; moderate-certainty evidence, downgraded due to risk of bias).
There may be little or no effect of multicomponent interventions on inpatient mortality compared to usual care (5.2% in the intervention group, compared to 4.5% in the control group, RR 1.17, 95% CI 0.79 to 1.74, I2 = 15%; 10 studies; 2640 participants; low-certainty evidence downgraded due to inconsistency and imprecision).
No studies of multicomponent interventions reported data on new diagnoses of dementia.
Multicomponent interventions may result in a small reduction of around a day in the duration of a delirium episode (mean difference (MD) -0.93, 95% CI -2.01 to 0.14 days, I2 = 65%; 351 participants; low-certainty evidence downgraded due to risk of bias and imprecision). The evidence is very uncertain about the effect of multicomponent interventions on delirium severity (standardised mean difference (SMD) -0.49, 95% CI -1.13 to 0.14, I2=64%; 147 participants; very low-certainty evidence downgraded due to risk of bias and serious imprecision). Multicomponent interventions may result in a reduction in hospital length of stay compared to usual care (MD -1.30 days, 95% CI -2.56 to -0.04 days, I2=91%; 3351 participants; low-certainty evidence downgraded due to risk of bias and inconsistency), but little to no difference in new care home admission at the time of hospital discharge (RR 0.77, 95% CI 0.55 to 1.07; 536 participants; low-certainty evidence downgraded due to risk of bias and imprecision). Reporting of other adverse outcomes was limited.
Our exploratory component network meta-analysis found that re-orientation (including use of familiar objects), cognitive stimulation and sleep hygiene were associated with reduced risk of incident delirium. Attention to nutrition and hydration, oxygenation, medication review, assessment of mood and bowel and bladder care were probably associated with a reduction in incident delirium but estimates included the possibility of no benefit or harm. Reducing sensory deprivation, identification of infection, mobilisation and pain control all had summary estimates that suggested potential increases in delirium incidence, but the uncertainty in the estimates was substantial.
Evidence from two trials suggests that use of a liberal transfusion threshold over a restrictive transfusion threshold probably results in little to no difference in incident delirium (RR 0.92, 95% CI 0.62 to 1.36; I2 = 9%; 294 participants; moderate-certainty evidence downgraded due to risk of bias).
Six other interventions were examined, but evidence for each was limited to single studies and we identified no evidence of delirium prevention.