World Delirium Awareness Day 2019, delirium and risk of falls in the hospital setting

Background Delirium is an acute change in cognition, common among older hospitalized patients, however, patients of all ages are at risk of delirium during a hospital stay. The International Federation of Delirium Societies promotes, each year, a World Delirium Awareness Day, to raise the awareness of, not just recognizing delirium in the hospital setting, but ensuring interventions are in place to prevent the development of delirium. Hospitalized patients with delirium have increased risk of adverse events such as falls, pressure injury, malnutrition, increased length of stay, increased health care costs, and mortality. This clinical audit aimed to estimate the risk of a subsequent fall, following an acute episode of in-hospital delirium, across a broad cross-sectional of clinical settings. Methods Seventeen adult acute inpatient wards across a health district, undertook an audit of the number of admitted patients who had had at least one episode of delirium since being admitted to hospital. Using the hospital-based incident management reporting system, the rates of subsequent falls was compared between delirium and non-delirium patients. Results Fifty of the 473 patients (11.4%) were identied by the nursing staff to have had at least one episode of delirium since admission. The proportion of fallers among the delirium and non-delirium patients were 10% and 2%, respectively (p = 0.004). The rate of falls per 1000 patient days was 6.45 (95% condence interval (CI) 2.1 to 15.1) among delirium patients, compared to 2.12 (95% CI 1.0 to 4.0) among patients without delirium. The risk of falling among delirium patients was 4.25 higher compared to non-delirium patients (adjusted hazard ratio (HR) = 4.25, 95% CI 1.26 to 14.39). Conclusion This clinical audit has been able to show that an acute episode of delirium increases the risk of an in-hospital fall fourfold. Importantly, these results have highlighted the need for a hospital wide approach, to not just in identifying delirium, but the need to have interventions in place to reduce the risk of delirium. In other words, delirium prevention should be ‘core business’

as falls, pressure injury, malnutrition, increased length of stay, increased health care costs, and mortality.
This clinical audit aimed to estimate the risk of a subsequent fall, following an acute episode of inhospital delirium, across a broad cross-sectional of clinical settings. Methods Seventeen adult acute inpatient wards across a health district, undertook an audit of the number of admitted patients who had had at least one episode of delirium since being admitted to hospital. Using the hospital-based incident management reporting system, the rates of subsequent falls was compared between delirium and nondelirium patients. Results Fifty of the 473 patients (11.4%) were identi ed by the nursing staff to have had at least one episode of delirium since admission. The proportion of fallers among the delirium and non-delirium patients were 10% and 2%, respectively (p = 0.004). The rate of falls per 1000 patient days was 6.45 (95% con dence interval (CI) 2.1 to 15.1) among delirium patients, compared to 2.12 (95% CI 1.0 to 4.0) among patients without delirium. The risk of falling among delirium patients was 4.25 higher compared to non-delirium patients (adjusted hazard ratio (HR) = 4.25, 95% CI 1.26 to 14.39). Conclusion This clinical audit has been able to show that an acute episode of delirium increases the risk of an inhospital fall fourfold. Importantly, these results have highlighted the need for a hospital wide approach, to not just in identifying delirium, but the need to have interventions in place to reduce the risk of delirium. In other words, delirium prevention should be 'core business' of all nursing care, across the acute hospital setting.

Background
Delirium is an acute change in cognition, common among older hospitalized patients [1], however, patients of all ages are at risk [2][3][4]. Unfortunately, delirium is often not recognized, and therefore poorly treated in the hospital setting [5][6][7]. For this reason, each year the International Federation of Delirium Societies promotes a World Delirium Awareness Day, to raise the awareness of, not just recognizing delirium in the hospital setting, but ensuring interventions are in place to prevent the development of delirium.
Hospitalized patients with delirium have increased risk of adverse events such as falls, pressure injury, malnutrition, increased length of stay, increased health care costs, and mortality [1,2,8]. Falls have been described as one of the most commonly reported adverse events among the elderly admitted to hospital.
In particular, falls in the acute hospital setting can result in serious injuries, prolong hospital stay, and can be associated with unexpected death [9][10][11]. Approximately 2% to 12% of patients fall during a hospital stay [10], with this rate increasing with age, and has been reported to be as high as 46% among patients cared for in stroke rehabilitation units [12]. However, consistent strong evidence for the bene t of many interventions currently used in the hospital setting, to prevents falls, has not been found when systematically reviewed by experts in this area -in fact, it was concluded a "multifactorial intervention may reduce the risk of falls" in the acute hospital setting [9,13]. Considering that most modern acute hospitals actively attempt to identify patients at the greatest risk of falls, and institute a number of interventions to prevent a fall, the conclusion reached by the Cochrane Review (quoted above) is quite sobering, and may indicate that only marginal gains may be obtained by implementation of further interventions to reduce falls in the acute hospital setting. It is for this reason, that we became interested in widening the scope of falls prevention when discovering the relationship between an episode of delirium in the hospital setting and a subsequent fall has been previously described [14][15][16]. However, previous work in this area was limited to retrospective review of the clinical notes of in-hospital fallers, nding documented evidence of delirium prior to a fall, or some prospective studies of elderly patients in the hospital setting, among which an association between delirium and falls was observed [17][18][19]. No studies to date have explored the relationship between an acute episode of delirium and subsequent falls risk across a broad cross-sectional of clinical settings, not just among elderly hospitalized patients. For this reason, this clinical audit was speci cally aimed at estimating the risk of subsequent fall, following an acute episode of in-hospital delirium, across a broad cross-sectional of clinical settings.

Methods
As part of the World Delirium Awareness Day (WDAD) 2019 (March 13 th ), seventeen adult acute inpatient wards across the (redacted for review) health district, undertook an audit of the number of admitted patients who had had at least one episode of delirium since being admitted to hospital. Patients from these seventeen wards were then followed until discharge or an incident fall. This project is part of an ongoing program of nursing-led investigation, across our local health district, concentrating on Frailty, Falls, Fracture and Delirium (The Triple-FD program).

Subject and setting
The South Western Sydney Local Health District provides public hospital care for approximately a million residents, with ve acute care hospitals, with approximately 230,000 separations each year. The seventeen wards [no. of wards] included in our clinical audit, offer adult acute inpatient care in the following clinical areas: (1) Aged care [3]; (2) Medical [3]; (3) Surgical [7]; Mixed medical/surgical [2]; and, (4) Rehabilitation [2]. All inpatients of these seventeen wards on the morning of WDAD (Wednesday, March 13 th , 2019) where included in the audit. Inpatients on the 13 th of March, 2019 across the seventeen wards were followed-up for one of the following events: (1) an incident fall; (2) discharge without fall; or, until the 30 th of April, 2019, without falling or being discharged from hospital.

Identi cation of delirium
All acute hospitals across our local health district use the Confusion Assessment Method (CAM) to identify acute episodes of delirium among any patient who appears to be disorientated or confused, or who has any change in behaviour, or level of consciousness [20]. The CAM is based on four main area of assessment: (1) acute onset and uctuating course (Is there evidence of an acute change in mental status from baseline? If so, did the abnormal behaviour uctuate during the day?); (2) Inattention (did the patient have di culty focussing attention during the interview?); (3) Disorganised thinking (was the patient's thinking disorganised?); and, (4) Altered level of consciousness (overall, how would you rate the patient's level of consciousness?) [20].

Identi cation of falls
Reporting of in-hospital falls (regardless of injury) is mandatory for all clinical staff, and are entered into a dedicated Incident Information Management System (IIMS) [21] as part of routine documentation. All inhospital falls up until April 30 th , among clinical audit participants were included.

Ethical considerations
Using our state-wide guide on assessing ethical risk [22], and due to the nature of this clinical audit using routinely collected data, that constitutes usual patient care and documentation, ethical review was considered to be unwarranted for the purposes of publication of the results of this clinical audit.

Statistical methods
Characteristics of patients included in the clinical audit are presented as descriptive statistics, based on delirium status. Rates of delirium and incident falls during follow-up, based on type of ward and delirium status, were calculated per 1000 patient days, and 95% con dence intervals were also calculated, comparison of groups was undertaken using Poisson regression [23]. The risk (presented as hazard ratios (HR), and 95% con dence intervals) of an incident fall during follow-up and at least one episode of acute delirium since admission was estimated using Cox's proportional hazards models [24]. Veri cation of the proportional hazards assumption of the Cox models was based on a visual inspection of smoothed Schoenfeld residual plots [25]. All analyses were performed using the R language for statistical computing [26].

Results
The characteristics of the 437 patients included in the WDAD 2019 (March 13 th ) clinical audit of the incidence of delirium since admission are presented in Table 1. Fifty of the 473 patients (11.4%) were identi ed by the nursing staff to have had at least one episode of delirium since admission. The age of patients ranged from 17 to 101 years, patients with delirium were older (82 years versus 70 years, p < 0.001), and more likely to be female (14% versus 9%, p = 0.076). The highest rates of delirium were reported in the Aged Care setting (32%), and lowest rates were reported in the mixed medical/surgical wards. Fourteen incident falls were reported, up until the 30 th of April 2019, the median time of follow-up was 6 days (IQR 1-16), and the proportion of fallers among the delirium and non-delirium patients were 10% and 2%, respectively (p = 0.004). The rate of falls per 1000 patient days was 6.45 (95% CI 2.1 to 15.1) among delirium patients, compared to 2.12 (95% CI 1.0 to 4.0) among patients without delirium (p = 0.046). Overall 4 deaths were reported among the 437 patients (3 versus 1, p = 0.310, delirium and nondelirium patients, respectively).
The rates (per 1000 acute bed days) of delirium and incident falls based on type of ward are presented in Table 2. For example, the highest rate of delirium, per 1000 acute bed days, was observed in the aged care setting, 13.9 (95% CI 8.0 to 22.6), and the lowest rate in the mixed medical/surgical wards, 2.5 (95% CI 0.1 to 13.6.9). The highest rate of fall, per 1000 acute bed days of follow-up was observed in the mixed medical/surgical wards, 4.9 (95% CI 0.6 to 17.7), and the lowest fall rate in the aged care setting, 1.7 (95% CI 0.2, 6.3).
Kaplan-Meier plots of the cumulative risk of falling, based on delirium status are presented in Figure 1. Both crude and adjusted (adjusted for sex, age, and ward type) risk of falling during follow-up among delirium patients compared to non-delirium patients are presented in Table 3. The risk of falling among delirium patients was 4.25 higher compared to non-delirium patients (HR = 4.25, 95% CI 1.26 to 14.39), after adjusting for sex, age and ward type. The c-statistic (concordance) for the delirium only and adjusted model were 0.622 and 0.729, respectively.

Discussion
This clinical audit of adult patients admitted to a diverse group of hospitals wards across a local health district, has been able to show that an acute episode of delirium increases the risk, fourfold, of an inhospital fall. Importantly, this observed increased risk of falling in the hospital setting, highlights the need for a hospital wide approach, to not just in identifying delirium, but the need to have interventions in place to reduce the risk of delirium, in an attempt to reduce associated adverse events such as a fall.
The ndings of this clinical audit con rm the results of a number of observational studies [16], and delirium prevention trials, that not only had shown an increased risk of falls among hospitalised patients with delirium, but a reduced risk of falling among delirium prevention intervention groups when compared to usual care [27]. Earlier work in this area had highlighted an association between falling and delirium in the hospital setting, but was limited to retrospective review of the clinical notes of patients who had fallen [14,15], or prospective observation of elderly patients cared for in the aged care setting. Importantly, this clinical audit has included a broad cross-sectional of adult acute inpatients and shown a strong relationship between an acute episode of delirium and risk of a subsequent fall.
The results of this clinical audit need to be considered in the context of some potential limitations. Firstly, the identi cation of delirium in the hospital setting is often subject to some error. However, the majority of this error is related to false negatives (sensitivity of 0.81) when the CAM had been compared to a more exhaustive assessment of delirium using the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) [28]. Importantly, false positives rates have been estimated to be low (1%) when also compared to DSM IV [28]. The consequences of this would be that across the wards which were included in our clinical audit, delirium rates may be under estimated, and using the method suggested by Kelsey [29] (using the above estimates of sensitivity and speci city of 0.81 and 0.99, respectively), the overall observed rate of 11.4% would increase to approximately 13%. There is no suggestion that the misclassi cation of delirium would be related to subsequent fall status, and therefore this error would be considered non-differential in nature, among fallers and non-fallers. In other words, we expect our estimates of the risk for falls related to delirium status would not have been biased by the under recognition of delirium, due to the equality of error (non-differential error) in the recognition of delirium between patients subsequently falling and those who did not fall. However, there may also be some under-reporting of falls, and in a similar manner we expect this to be non-differential in nature between delirium and non-delirium patients.
A strength of this clinical audit if that we have been able to include a diverse cross-section of hospitalised patients receiving, aged care, surgical, medical and rehabilitation, representing the diverse population of patients that are at risk of experiencing an acute episode of delirium in the hospital setting. Therefore, we propose that our results highlight the need to ensure delirium prevention should be 'core business' of all nursing care across the hospital, not just in the aged care setting. As, an increasing body of evidence supports the bene ts of non-pharmacological, multicomponent nurse-led interventions to reduce the incidence, severity and duration of delirium among adults cared for in the acute hospital setting [1,30,31].
The clinical implications of recognising the importance of delirium prevention in the hospital setting, in an attempt to improve the quality and safety of all patients, is not a novel by any means [2]. However, highlighting to all nursing staff across the hospital the importance of delirium prevention, not just in the aged care setting, but among medical and surgical specialties will ensure that good quality and safe care of patients at risk delirium and falls, can be guaranteed, irrespective of the wards setting of care.

Conclusions
This clinical audit has been able to show that an acute episode of delirium increases the risk of an inhospital fall fourfold. Importantly, these results have highlighted the need for a hospital wide approach, to not just in identifying delirium in the hospital setting, but the need to have interventions in place to reduce the risk of delirium, in an attempt to reduce the risk of associated adverse events such as a fall. In other words, delirium prevention should be 'core business', of all nursing care across the acute hospital setting.

Declarations
Ethics approval and consent to participate -This study was a clinical audit and formal ethics approval was not sort based on health department policy [22] Consent for publication -not applicable Availability of data and materials -The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.    Figure 1 Kaplan-Meier plot of the risk of fall based on delirium status.