Barriers to healthcare professionals recognizing and managing delirium in older adults during a hospital stay: A mixed-methods systematic review

Aim: To investigate barriers to healthcare professionals recognizing and managing de - lirium in hospitalized older people. Design: A mixed-methods systematic review. PROSPERO ID: CRD42020187932. Data Sources: MEDLINE, EMBASE, PsycINFO and CINAHL were searched (2007 to February 2023). Review Methods: Included studies focused on healthcare professionals' recognition and management of delirium for patients aged 65 years and over in a hospital ward or emergency department. Enhancing rigour, screening of results was conducted in - dependently by two researchers. Qualitative and quantitative data were tabulated separately and grouped. Data were compared to identify similarities and differences. All studies were quality appraised. Results: 43 studies were included; 24 quantitative, 16 qualitative and three mixed-methods. Data synthesis highlighted synergy between qualitative and quantitative findings. Barriers were reflected in six themes


| INTRODUC TI ON
Delirium is a common clinical syndrome with an acute onset characterized by disturbances of attention, cognition and consciousness (APA, 2013).It occurs secondary to physical triggers, particularly for older adults during an acute hospital stay (GMRC, 2022).Prevalence among people aged 65 years and above in United Kingdom (UK) hospitals has been reported at 21.2% (Welch et al., 2019), though this rate may be higher as it is asserted that delirium is consistently underdiagnosed in clinical Patient or Public Contribution: There was no patient or public contribution to this systematic review.
Implications for the Profession and Patient Care: Healthcare professionals can be better supported to be able to recognize and manage delirium during an acute hospital stay for older adults.This includes maximizing best care for those patients living with dementia, involving families and friends to help understand patients' baseline status and changes and supporting families and friends during this process.Of significance, attention to hospital IT infrastructures is warranted, integrating screening, assessment and care management plans in patients' electronic records and making these accessible to healthcare professionals caring for this patient population across care settings.
Impact: What problem did the study address?Delirium is a common condition experienced by older hospitalized patients, but it is consistently under-recognized which has implications for patient and organization outcomes.To help address this, understanding barriers to healthcare professionals recognizing and managing delirium for this patient population is paramount.
Where and on whom will the research have an impact?The findings of this original systematic review can contribute to hospital policy and protocol for the recognition and management of delirium in older patients.The findings can meaningfully contribute to workforce professional development for practitioners caring for older people during an acute hospital stay and for practitioners in primary and community settings involved in the follow-up of patients post hospital discharge.
For researchers, the findings indicate several research recommendations including investigating the impact of an education programme for nurses and other healthcare professionals on the recognition and management of the condition and understanding and investigating how best to support delirium-related distress experienced by patients and their families and practitioners.
Reporting Method: This systematic review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (Page et al., 2021).

K E Y W O R D S
delirium, health professionals, hospital, management, nurses, older people, recognition, screening, systematic review practice (Gibb et al., 2020;GMRC, 2022).Gibb et al.'s (2020) systematic review and meta-analysis reported that the prevalence and incidence of delirium in acute medical adult in-patients have remained broadly stable at about one in four older patients.Risk factors for delirium include having dementia or other cognitive impairment, aged ≥65 years, hospitalization, severe illness and current hip fracture (NICE, 2023).Delirium has also been reported as a probable COVID-19 symptom among older people living with frailty (Zazzara et al., 2020).Delirium is associated with several adverse outcomes for patients that include distress, increased length of hospital stay, higher re-admission rates, increased risk of a new admission to a long term care facility, functional and cognitive decline including increased risk of dementia and increased morbidity and mortality (NICE, 2023;Khambay et al., 2021;Khachaturian et al., 2020;Smyth et al., 2019;Soh et al., 2018), as well as distress for families and friends of patients, and practitioners (MacLullich et al., 2022;Toye et al., 2014).Early screening, recognition and intervention for older adults in hospital, as well as follow-up of patients in primary care is therefore paramount.
Despite high prevalence and clinical guidance that recommends delirium screening on admission to hospital for people at risk (NICE, 2023) and follow-up by primary care on discharge from hospital, it is estimated that between 32% and 66% of cases are under-recognized and between 30% and 40% are preventable (Fong et al., 2009;Oh-Park et al., 2018;Siddiqi et al., 2006).These findings suggest that screening is either inadequate or not performed leading to missed diagnosis and adverse patient outcomes (Kelly et al., 2019).Steis and Fick's (2008) systematic review of nurses' recognition of delirium reported that barriers to comprehensive recognition were lack of knowledge about delirium, inadequate documentation and assessment practices and inadequate communication between staff and patients and their families (Steis & Fick, 2008).However, the searches in the review by Steis and Flick were conducted over 15 years ago, focused solely on nurses' recognition of delirium, and only 10 studies met the inclusion criteria.Waterfield and Campbell's (2017) scoping review examined nursing assessment of delirium in acute hospital settings and drew evidence from 30 sources.They found that barriers to accurate diagnosis were lack of knowledge about delirium, the heterogenous presentation of the condition, difficulty differentiating delirium from dementia and depression and lack of baseline assessments to judge cognitive changes.We did not identify any systematic review since 2008 that has investigated barriers to how healthcare professionals recognize and manage delirium for older people during an acute hospital stay.It is not known to what extent barriers have persisted or evolved over more than a decade of changes to population demographics, as well as changes to health needs of older people and health care services.It is also not known whether similar or different barriers are experienced by different members of the multidisciplinary team.These are important questions given the availability of evidence-based guidance to prevent delirium or limit its complications (Woodhouse et al., 2019).Optimizing these strategies to achieve best practice for older people in hospital using a multidisciplinary approach requires a contemporary understanding of barriers.

| Aim
To understand the barriers to healthcare professionals recognizing and managing delirium experienced by older people during an acute hospital stay.

| Design
The review was designed and executed following Guidance on the Conduct of Narrative Synthesis in Systematic Reviews (Popay et al., 2006) and is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (Page et al., 2021).It was registered on the PROSPERO database for systematic reviews: CRD42020187932.

| Search strategy, information sources and eligibility criteria
A preliminary search was done to identify any previous systematic reviews on the topic.Steis and Fick (2008) provided a useful benchmark against which the findings of this review could be compared.This helped to inform the search strategy that was refined by working with a library specialist.An initial search was conducted on MEDLINE to identify index terms and keywords of relevant studies and the search strategy was developed incorporating the different syntax rules.Search terms included 'healthcare professionals ', 'delirium', 'recognition' and 'management' and Steis and Fick (2008).Table 1 presents an example of a full search strategy used.
Inclusion criteria were primarily quantitative, qualitative and mixed-methods research written in English, investigating barriers to healthcare professionals recognizing and managing delirium in people aged ≥65 years admitted to hospital.For inclusion, studies were required to use diagnostic criteria for delirium or a validated tool to assess changes in cognition.The focus was on wards providing acute care such as medicine and surgery as well as emergency departments.Intensive Care Unit (ICU) settings were excluded because of differing levels of patient consciousness, as were studies that focused on substance-induced delirium.

| Search selection
Identified citations were imported into EndNote X9 and duplicates removed.Titles and abstracts were independently assessed by LB and JF using the inclusion and exclusion criteria.Full-texts of potentially eligible studies were retrieved and assessed independently by LB and JF.There were no disagreements between reviewers.

| Quality appraisal
Quality was assessed using the Critical Appraisal Skills Programme checklist (CASP, 2018) for qualitative research; the Centre for Evidence-Based Management (CEBMa) 'Critical Appraisal of Survey' tool for surveys (CEBMa, 2014); the Joanna Briggs Institute Critical Appraisal Tools for observational and prospective designs (JBI, 2020a(JBI, , 2020b)); and the Mixed-Methods Appraisal Tool (MMAT) for mixed-methods studies (Hong et al., 2018).

| Data extraction
A bespoke data extraction tool captured key data items including setting, design, sample, how delirium was assessed and barriers to recognition and management.Data were extracted by LB and a sample of 10% was independently verified by JF.The screening process is outlined in Figure 1.

| Method used to present and synthesize results
Guided by Sandelowski et al. (2006), mixed-method data synthesis was undertaken using a segregated design that began with separate analyses of the extracted qualitative and quantitative findings using  (Page et al., 2021).
tabulation and grouping techniques (Popay et al., 2006).Themes identified from the qualitative and quantitative findings were compared to identify similarities (confirmation) and divergence (refutation).Results of this synthesis are presented diagrammatically in Figure 2.

| Study characteristics
The searches yielded 395 studies, with 83 duplicates which were removed.The title and abstract of 312 results were screened, and 58 full texts were reviewed.A final 43 studies were included for synthesis (Figure 1).The 43 studies involved 5596 healthcare professionals, focusing on recognition and management of delirium for hospitalized patients ≥65 years.For six studies, the sample size for healthcare professionals was not reported (Akinjogbin et al., 2020;Fick et al., 2018;Johansson et al., 2018;Merkin et al., 2014;Mossello et al., 2018;Randles et al., 2018).Thirteen studies were reported as conference abstracts.24 of the 43 studies had adopted a quantitative approach, and 16 a qualitative approach and three studies were mixed-methods.Most of the studies were conducted in the US

| Quality appraisal of individual studies
The 13 conference abstracts did not provide sufficient information to be quality assessed.For conference abstracts efforts were made to locate full-texts, three abstracts were replaced.The overall quality of included studies was moderate (Table 2).Qualitative studies and surveys used non-probability sampling methods to recruit healthcare professionals, consequently there was a high risk of selection bias where participants to the studies may differ significantly to the population of interest.Due to the lack of participant demographic information reported in conference abstracts, it was not meaningful to assess differences between respondents and non-respondents.For instance, doctors might be more likely to participate in a research study if they are more confident about their knowledge and/or experience with delirium.As Sri-On et al. (2014) discussed, self-report bias could be better or worse than what professionals reported as the recognition of delirium symptoms relies on memory skills which can be inexact.Only Rice et al. (2011) used a sample size based on pre-study power calculation.Response rates were reported in ten of the 43 studies (Davis & MacLullich, 2009;Kennelly et al., 2013;Limpawattana et al., 2018;Merkin et al., 2014;Pee, 2012;Reppas-Rindlisbacher et al., 2021;Sinvani et al., 2016;Sri-On et al., 2014;Wang & Mentes, 2009;Young et al., 2012) and varied from 30.8% (Hare et al., 2008) to 95.5% (Pee, 2012).
F I G U R E 2 Barriers to healthcare professionals recognizing and managing delirium in older adults during a hospital stay.

| Synthesis of results
There was synergy in barriers identified from the qualitative and quantitative findings.Six themes were identified: (1) healthcare professionals' knowledge and understanding; (2) communication challenges; (3) workforce development; (4) interprofessional working; (5) confounders; and (6) organizational constraints.The themes and subthemes are presented in Table 3.The significance of delirium for mortality, morbidity and readmission risk was underestimated (Kennelly et al., 2013;Le et al., 2011).Patient symptoms such as cognition fluctuations, inappropriate behaviour and communication, lethargy and difficulty to rouse were correctly identified but other symptoms were not (e.g., hallucinations, inattention and delayed responsiveness) and especially when patients had been given high doses of analgesic (Davis & MacLullich, 2009;Hare et al., 2008;Oberai et al., 2019).Nonspecific terms and labels referring to changes in cognition were used by some healthcare professionals to describe delirium, for example, confusion, non-specified International Classification of Diseases terms involving compromised cognitive function, awareness and disorientation (Alhaidari & Allen-Narker, 2017;Fick et al., 2007;Johansson et al., 2018;Schonnop et al., 2022).Some healthcare professionals were less familiar with specific risk factors for delirium, e.g., vision impairment, being male, a dementia diagnosis and having an internal device such as a urinary catheter (Hare et al., 2008;Meako et al., 2011;Rosado et al., 2019).Some healthcare professionals did not know if their hospital organization had a delirium management protocol in place and in two studies participants were unsure about the treatment pathway (Limpawattana et al., 2018;Ryan & Milligan, 2017).Doctors reported that their nursing colleagues lacked knowledge about delirium care, especially non-pharmacological interventions, and that this contributed to an increase in the use of pharmacological interventions or restraint (Van de Steeg et al., 2014).In two studies the underlying causes were not investigated or treated, rather physicians were focused on the acute illness (Johansson et al., 2018;Yevchak et al., 2012).Studies found that delirium was not screened for as part of the admission process and consequently diagnosis was delayed or missed (Kennelly et al., 2013;Le et al., 2011;Randles et al., 2018;Rosado et al., 2019;Sinvani et al., 2016;Sri-On et al., 2014;Young et al., 2012).In seven studies, healthcare professionals reported not knowing of a delirium assessment tool or that they seldom used one  (DSM) criteria used to diagnose delirium (Davis & MacLullich, 2009).
Cognition tended to be assessed using consciousness, alertness and orientation questions instead of using a recommended delirium assessment tool (Hare et al., 2008;Kennelly et al., 2013;Schonnop et al., 2022;Sinvani et al., 2016;Sri-On et al., 2014;Yevchak et al., 2012).Misunderstandings about delirium were reported in 13 studies.This included healthcare professionals believing that delirium is a normal response to aging, is not treatable or preventable and does not need medical attention (Fick et al., 2007;Hosie et al.,  Barriers to meaningful professional development on the topic included: training being too short, an excessive time lapse between completing CPD and using an assessment tool, challenges related to screening older people with severe cognitive impairment, having impaired reaction to external stimuli and being anxious about being tested (Fick et al., 2018;Van de Steeg et al., 2014).
Unless a formal diagnosis of delirium was made by an ED physician, no written communication was made (Day et al., 2008).Nurses have expressed concerns about a lack of respect from doctors for their opinions regarding patients' mental status.This lack of respect has resulted in nurses feeling less confident and competent in recognizing and assessing delirium (Hosie et al., 2014).Furthermore, nurses have reported that they often lack critical patient information (Emme, 2020).Despite using delirium screening tools, nurses have had difficulty discussing the results with doctors.The reasons for this difficulty were not reported.Nurses have emphasized the need for better communication and collaboration with doctors (Emme, 2020).They believe that if doctors were more assertive in reporting patient symptoms indicative of dementia, it could lead to quicker implementation of multidisciplinary interventions and improved patient outcomes (Hosie et al., 2014).Whilst nurses endeavoured to communicate well with the treating doctor, they felt that it was not always reciprocated (Hosie et al., 2014).
Communication between patients and healthcare professionals was identified as a barrier to effective assessment and management of delirium because healthcare professionals feared patients' reactions when administering the delirium screening tool (Emme, 2020).
Furthermore, some patients became frustrated with the delirium screening tool, experiencing fear and embarrassment when not able to answer questions (Hosie et al., 2014;Husser et al., 2021).To reduce patient anxiety, healthcare professionals were reported as playing down assessment of cognitive status, referring to the CAM as 'a couple of silly questions'; 'not a big deal' which prevented a thorough assessment (Husser et al., 2021).Patient-healthcare professional communication was challenged when patients were less responsive (Fick et al., 2018), and delirium assessment was sometimes interrupted or declined because of physical symptoms (e.g.pain, sedation, fatigue, coughing and dyspnoea) (Husser et al., 2021).

Interprofessional working
A barrier to delirium assessment and management was lack of clarity about professional responsibility which was identified in qualitative and quantitative findings (Davis & MacLullich, 2009;Eagles et al., 2022;Emme, 2020;Kennelly et al., 2013;Limpawattana et al., 2018;Ryan & Milligan, 2017).Diagnosing delirium was reported as being a doctor's responsibility (Reppas-Rindlisbacher et al., 2021), but nurses reported that doctors did not take responsibility for the management plan which caused disagreement within teams (Emme, 2020).Neglecting to address the emotional needs of patients in the assessment and management of delirium has been recognized as a barrier (Emme (2020), Kai-Chung Wong et al. (2018), Hosie et al. (2015), and Hosie et al. (2014)).This highlights the importance of holistic assessment and the contribution of all members of the interprofessional team in the management of delirium.

Organizational constraints
Organizational constraints were reported in 21 studies as barriers to effective delirium assessment and management.These Emme, 2020).These factors were not conducive to patient rest and sleep and contributed to delusions (Day et al., 2008).Other distractions impacting negatively on healthcare professionals' assessment included background conversations and insufficient space to move with ease around the patient area (Husser et al., 2021;Reppas-Rindlisbacher et al., 2021).
Practice guidance was a key barrier, with reports of guidelines being limited, too long and difficult to apply in practice, with inconsistencies between the guideline recommendations and the actual management (Emme, 2020;Hosie et al., 2014).For instance, nurses in Emme ( 2020) study shared that guidelines conflicted with their experience and they preferred advice from experienced colleagues, and that delirium guidelines clashed with other practice guidance, e.g., hospital guidelines stipulated that patients with a diagnosis of critical illness had to be kept awake during the night for monitoring purposes or that all patients need to be awake by six in the morning to have their vital signs measured.This conflicted with guidance that for patients with a delirium sleep should be prioritized (Emme, 2020).Healthcare professionals wanted a clear and simple delirium follow-up care guideline (Hosie et al., 2015;Oberai et al., 2019).Local clinical guidelines were considered a priority as not having an action plan led to uncertainty about care (Oberai et al., 2019).Despite an initial reluctance to include screening tools in a delirium care pathway, nurses agreed on the value of these tools and the need to assess delirium at every shift to familiarize themselves with a patient's 'fluctuating' state (Oberai et al., 2019).
Screening tools that were not easy to use and unclear practice guidance and protocols were identified as barriers.Healthcare professionals highlighted limitations of delirium screening tools e.g., in the CAM assessment tool there is insufficient space to detail observations, and 'yes' 'no' answers are restrictive (Kai-Chung Wong et al., 2018).Professionals were not able to recall or did not know the CAM items when asked suggesting that the tool was probably used retrospectively rather than at the bedside (Kai-Chung Wong et al., 2018;Schonnop et al., 2022).Nurses were not sure about the best timing to administer the NuDESC to ensure that the score was reliable and if additional screening was required when patients displayed cognition changes, they perceived it was difficult to translate the clinical symptoms in a standardized tool (Hosie et al., 2015).The specificity of screening assessment tools was criticized by healthcare professionals in Oberai et al. (2019) study and for some it was considered a waste of time to administer a screening tool for a patient admitted to the unit with a confirmed delirium (Oberai et al., 2019).
Not knowing patients made assessment difficult (Emme, 2020), and for patients with a frailty this could be a lengthy and tiring process (Hosie et al., 2014;Reppas-Rindlisbacher et al., 2021).
Some professionals did not know how to file the results of a cognition and delirium assessment in patients' medical records (Alhaidari & Allen-Narker, 2017;Bambach et al., 2019).Documentation requirements were sometimes perceived to be inadequate, frustrating and devalued healthcare professionals' clinical decision making about symptoms and progress (Emme, 2020; Kai-Chung Wong et al., 2018;Sinvani et al., 2016).Healthcare professionals suggested that clinical documentation could be improved by an IT system that enabled screening and assessment tools to be integrated into a patient's electronic medical record that could be accessed by all MDT members (Sinvani et al., 2016).

| DISCUSS ION
This rigorous multi-method systematic review has identified that barriers to health professionals recognizing and managing delirium are significant issues that compromise safety and effectiveness of care for older adults during an acute hospital stay, with consequences also for patients' family and friends, clinicians and healthcare organizations.This finding is concerning particularly given the focus and investment in quality improvement in national (e.g., GMRC, 2022; Vardy & Thompson, 2020) and international (e.g., Azhar et al., 2022) healthcare contexts.

| Knowledge and understanding to improve delirium recognition and management
Similar to Steis and Fick, our review identified a lack of knowledge about the condition, but it was noteworthy that for healthcare professionals in our review the significance of delirium for mortality, morbidity and readmission risk was underestimated.A key finding of our review was that healthcare professionals had incomplete knowledge of delirium, its symptoms, risk factors, impact on patients and others, screening tools, practice guidelines and care management.This suggests that delirium may not be addressed in sufficient depth in initial preparation programmes for nurses and other healthcare professionals (Papaioannou et al., 2023) and that continuing professional development (CPD) on this topic is variable; of significance 18 of the 43 studies in this review reported a lack of CPD on delirium.biguous.An example of this is delirium superimposed on dementia (DSD) which can make delirium difficult to recognize and assess due to the similarity of symptoms.DSD has a prevalence ranging from 22% to 89% in older hospitalized patients, assessment is more difficult and a delirium diagnosis is more likely to be missed because of this (Fick, 2022;Richardson et al., 2016).Delirium in patients living with dementia is associated with worse functional and cognitive outcomes, persistent or irreversible delirium, increased risk of hospitalization and mortality in comparison to patients with delirium only (Han et al., 2022;Nitchingham & Caplan, 2021).
Delirium can also increase the risk of dementia and vice versa (Fong & Inouye, 2022).
Vardy and Thompson's (2020) quality improvement study to improve delirium detection in the emergency department (ED) and outcomes in an acute hospital adopted a multifaceted approach that included a focus on training, education, leadership and technology.
Their results demonstrated that delirium assessment and diagnosis improved following an educational intervention targeting nurses, doctors and healthcare assistants.Of significance, in our systematic review was a lack of interprofessional working; nurses expressed concerns about a lack of respect from doctors for their opinions regarding patients' mental status.This lack of respect resulted in nurses feeling less confident and competent in recognizing and assessing delirium (Hosie et al., 2014).
Hoch et al. (2022) found that case vignettes reflecting realistic scenarios helped nurses to develop their clinical skills for recognizing, managing and preventing delirium.Such initiatives are encouraging, helping to raise awareness and improve knowledge, understanding and clinical competence.They can also address the importance of early screening and recognition.Our review found that delirium was not consistently screened for as part of the admission process and consequently diagnosis was delayed or missed (Kennelly et al., 2013;Le et al., 2011;Randles et al., 2018;Rosado et al., 2019;Sinvani et al., 2016;Sri-On et al., 2014;Young et al., 2012).The latest NICE guidance (2023) on the prevention, diagnosis and management of delirium in hospital and long-term care, emphasizes that within 24 h of admission to hospital people at risk for clinical factors contributing to delirium should be assessed.

| Screening and assessment
Delirium screening should be embedded in a comprehensive protocol that includes risk factors, assessment, management and care, and prevention (Eagles et al., 2022).Key to effective screening and rec-  & MacLullich, 2009;Kennelly et al., 2013;Le et al., 2011;Oberai et al., 2019;Schonnop et al., 2022;Young et al., 2012).For some professionals, there was tension between using their individual clinical decision-making skills and having to use designated screening or assessment tools.Screening and assessment tools should be

| Specialist and advanced roles
Initial and continuing education on delirium for nurses and other healthcare professionals is essential but addressing barriers to recognizing and managing delirium for older patients during an acute hospital stay requires a multi-faceted approach.At an organizational level, having delirium specialist teams in place has been shown to improve delirium screening (GMRC, 2022).
Similarly, recognition was improved when geriatric teams were embedded in admissions units (GMRC, 2022).et al., 2018;Hosie et al., 2014;Husser et al., 2021).Family and friends can make an important contribution to healthcare professionals understanding patients' baseline status and changes in cognitive function, perception, physical function, and social behaviour (Hosie et al., 2014;Oberai et al., 2019).These different roles demonstrate a commitment to providing high-quality care for older people with a delirium.Gerontological care is regarded as less specialized and less attractive than healthcare fields such as oncology and intensive care (Van de Steeg et al., 2014).Negative attitudes towards older people with a delirium can be reinforced by symptoms such as anxiety, agitation, confusion, hallucinations, and aggression (Papaioannou et al., 2023).Education and training can help challenge negative attitudes towards older people with a delirium as well as negative stereotypes about older people, ageing, and caring for older people (Burnes et al., 2019;Jenkin et al., 2016).
It was noteworthy that organizational constraints were reported in 21 studies as barriers to effective delirium assessment and management.These included challenges with the physical environment, staff shortages and staff not having enough time because of busy workloads and competing priorities, and clear practice guidelines not being available.The clinical environment was also identified as a barrier with disturbances and unnecessary stimuli for patients which were not conducive to patient rest and sleep.

| S TRENG TH S AND LIMITATI ON S OF THIS SYS TEMATI C RE VIE W
This is a substantial systematic review of 43 studies conducted using qualitative, quantitative, and mixed-methods approaches.The last systematic review by Steis and Fick (2008) was conducted over 15 years ago, focused solely on nurses' recognition of delirium, and included only 10 studies.The findings of our review contribute to a comprehensive understanding of the topic and how recognition and management of delirium can be improved further for older patients during an acute hospital stay.Methodologically, strengths included the first author working closely with a library specialist to develop and refine the search strategy, screening of results by two independent researchers, and data extraction using a bespoke tool.A limitation of the review is that it included only studies written in the English language which may have excluded relevant research.It is possible that not all relevant sources were identified via the selected electronic databases and this is acknowledged as a potential limitation.Thirteen of the included studies, the majority of which were surveys, were reported as conference abstracts and it was not possible to fully assess their quality.We searched for published academic papers and contacted the authors although were not able to find any additional information.This is not unusual; Scherer et al. (2018) found the proportion of conference papers that were published in full is low.All thirteen studies contributed to the identified themes.
However, several included studies that contributed data to the understanding of the majority themes.As such the conference abstracts contributed some data but less than other studies where a full published paper is available.We found no evidence that the conference abstracts distorted the analysis.We have included the conference abstracts for completeness and to reduce publication bias.

| CON CLUS IONS
related synonyms combined with MeSH terms, Boolean operators and Truncation.The MEDLINE, EMBASE, PsycINFO and CINAHL databases were searched from 2007 to February 2023.The reference list of eligible studies were hand-searched to identify any further studies.The start date of 2007 was chosen to capture literature published since the review of

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1.
Healthcare professionals' knowledge and understanding Lack of knowledge and understanding as a barrier to recognizing and managing delirium included healthcare professionals not knowing about the condition (n = 21 studies), risk factors (n = 9 studies), screening tools and/or guidelines (n = 17 studies), care management (n = 14 studies) and not understanding fully the impact of the condition (n = 13).
Language barriers were reported in two studies(Reppas-  Rindlisbacher et al., 2021;Kai-Chung Wong et al., 2018) and cultural barriers in one(Wang & Mentes, 2009).In Wang and Mentes' early study(2009), carried out in China, the tradition of respect for older people influenced nurses not to assess and record cognitive and behavioural changes for patients displaying symptoms as a sign of respect(Wang & Mentes, 2009).Nurses had difficulty assessing delirium 13652648, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jan.16018by Test, Wiley Online Library on [18/12/2023].See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions)on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License using the CAM for patients with limited English language proficiency (Kai-ChungWong et al., 2018; Reppas-Rindlisbacher et al., 2021)    and reported that patients' confusion was made worse by nurses having difficulty explaining the reasons for the assessment(Reppas-  Rindlisbacher et al., 2021).Language challenges were compounded by not having access to an interpreter to support the assessment process (Kai-ChungWong et al., 2018; Reppas-Rindlisbacher et al., 2021).
included challenges with the physical environment (n = 5); staff shortages and staff not having enough time because of busy workloads and competing priorities (n = 18) and clear practice guidelines not being available (n = 12).The clinical environment was identified as a barrier with disturbances and unnecessary stimuli for patients due to factors such as loud calling systems, lighting, general noise of patients and families and staff, frequency of room changes for patients and the environment being too hot or humid(Day et al., 2008;

13652648, 0 ,
Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jan.16018by Test, Wiley Online Library on [18/12/2023].See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions)on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vardy et al. (2023) have asserted that education is central to enhancing delirium diagnosis and care.Education and training for healthcare professionals should address the complexity of screening, assessing and caring for older people with delirium during an acute hospital stay, who are likely to have multiple conditions and consequently signs and symptoms may be varied, vague and am- ognition is practitioners being competent to use the recommended tools.NICE (2023) recommends the use of the 4AT, which has been validated for use by different healthcare professionals and requires minimal training.A key review finding was that healthcare professionals reported not knowing of a delirium assessment tool or that they seldom used one (Campioni-Norman & Vizcaychipi, 2017; Davis Optimal care for older patients with delirium requires a multicomponent approach delivered by a multiprofessional team(NICE, 2023).Nurses and healthcare professionals need specialist skills to identify complex patterns of signs and symptoms and confounders to make a timely diagnosis and management plan for delirium in the older person.Advanced and specialist nurse roles in the fields of delirium and dementia make an important contribution to advancing the care of the older person in hospital and following discharge from hospital; nurses leading on patient care but in collaboration with their multiprofessional colleagues(Carey et al., 2022;Davis & Price, 2023).Advanced and specialist nurses have expertise to navigate the challenges encountered during the patient journey and therefore have a key role in supporting patients and their families and friends.For example, communication and environmental challenges for older patients with delirium who are living with dementia; several studies in this review reported poor patient-healthcare professional communication(Emme, 2020;Fick Despite it being a common and serious condition in hospital settings and the availability of screening tools and evidence-based practice guidance, delirium is still under-recognized for older patients which compromises safe and effective care for patients, increases the anxiety and concerns of their families and friends, increases the concerns and workload of healthcare professionals, and increases the pressure of health systems.This systematic review has provided insight about barriers for healthcare professionals that focused on healthcare professionals' knowledge and understanding, communication, workforce development, interprofessional working, confounders, and organizational constraints.There are opportunities for this condition to be addressed more fully in initial preparation programmes for nurses and other healthcare professionals, CPD, and advanced education and training for specialist practitioners, 13652648, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jan.16018by Test, Wiley Online Library on [18/12/2023].See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions)on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

TA B L E 1
Example of a full search strategy.
Table 2 presents a summary of the study characteristics.