Delirium Assessment in Elderly Patients: A Literature Review

Introduction

Delirium was first described approximately 2,500 years ago, yet it remains frequently unrecognized and poorly understood. Delirium is defined as a common syndrome that primarily affects elderly people. It is an acute neuropsychiatric condition that affects the patient's global cognitive function — most notably attention, working memory, and consciousness (Hosie, Agar, Lobb, Davidson, & Phillips, 2014). The condition is often undiagnosed, despite affecting approximately 14–24 percent of hospital admissions. Delirium can be a fatal condition, costing over $164 billion annually in the United States. In approximately 30–40 percent of reported cases, delirium is preventable. When examining health care quality for seniors, delirium has been included in the patient safety agenda. There are varied clinical presentations of delirium, and specific motor subtypes — hypoactive and hyperactive — have been extensively described in the literature. Delirium is associated with adverse patient outcomes, including increased length of hospital stay, higher mortality, increased rates of institutionalization, more hospital-acquired complications, readmission, and dementia (Hosie et al., 2014). These outcomes produce significant morbidity for both patients and their carers, causing considerable short- and long-term distress, as well as increased costs of care.

Delirium is considered a form of acute brain failure — a multifactorial syndrome analogous to acute heart failure. Its onset is often triggered by major surgery or sepsis, and this may help illuminate the concept of cognitive reserve (the brain's resilience in withstanding external factors) (Hosie et al., 2014). Numerous studies have analyzed delirium and its onset, particularly among patients in the ICU. However, there is limited research on the assessment of delirium in older patients who are not in the ICU or otherwise hospitalized. There is also a lack of knowledge among nurses regarding how to assess a patient for delirium; in most cases, patients are treated for other underlying conditions rather than for delirium itself (Adamis, De Jonghe, Van Munster, Meagher, & De Rooij, 2015). Therefore, there is a need to increase knowledge and understanding of the condition.

In the past, delirium was considered a mental status problem. With advances in the field and more systematic observation, however, delirium is now recognized as a disorder of cognition, with global cognitive impairment and inattention as its key features (Inouye, Westendorp, & Saczynski, 2014). Making this distinction is critical to identifying delirium, which is most commonly associated with poor long-term outcomes. It may not always be easy to distinguish an overly sedated patient from a delirious one, but this clinical distinction is important.

All articles used for this review were obtained by searching the Medline, PubMed, and EBSCO databases, with the goal of identifying studies focused on the assessment of delirium in patients outside the ICU. The review specifically targeted studies examining delirium that was not acquired after hospitalization. All articles included in the literature review were published between 2014 and 2017.

Literature Review

According to Leonard et al. (2016), prevalence rates on hospital admission have been shown to range from 8 to 17 percent among hospitalized patients aged 55 years and older. In nursing homes, the prevalence of delirium has been reported at 40 percent. Delirium is consistently associated with increased mortality across all nonsurgical patient populations. Patients who develop delirium while in the ICU face a 2- to 4-fold increased risk of death, while those who develop delirium on general medical wards face a 1.5-fold increased risk. Patients who present with delirium in the emergency department face a 70 percent increased risk of death within the first six months of their visit (Leonard et al., 2016). This clearly demonstrates that delirium is associated with high mortality rates and, if not properly diagnosed, can result in premature patient death (Adamis et al., 2015).

Assessing delirium is not straightforward, and in many instances the condition goes unnoticed or is overlooked by nurses. To properly diagnose delirium, a brief cognitive screening is necessary. The primary diagnostic features of delirium include a fluctuating and acute course of symptoms, impaired level of consciousness, inattention, and disturbance of cognition. Additional supportive features include perceptual disturbance, delusions, sleep-wake cycle disturbance, inappropriate behavior, psychomotor disturbance, and emotional lability (Adamis et al., 2015). In the published literature, over 24 delirium instruments have been used. The most widely used instrument is the Confusion Assessment Method (CAM), which has been validated in high-quality studies involving more than 1,000 patients, demonstrating a sensitivity of 94 percent, a specificity of 89 percent, and high interrater reliability.

Risk Factors and Nursing Knowledge Gaps

According to Balas et al. (2014), a single factor can result in delirium, but in older persons the condition is most commonly multifactorial — a characterization that is well-validated and widely accepted. The development of delirium typically involves complex interrelationships between a vulnerable patient with multiple predisposing factors and exposure to precipitating factors or noxious insults. In patients who are considered highly vulnerable to delirium — such as those with underlying multimorbidity or dementia — a relatively benign insult, such as a single dose of sleeping medication, could be sufficient to trigger or precipitate delirium (Smulter, Lingehall, Gustafson, Olofsson, & Engström, 2015). In a younger patient, by contrast, delirium would only typically develop after exposure to a series of such insults. The implications of this multifactorial etiology are that addressing a single risk factor is unlikely to resolve delirium; multi-component approaches are needed for both prevention and treatment.

Many risk factors for delirium have been identified to date. Those most consistently identified at the time of patient admission include dementia or cognitive impairment, vision impairment, functional impairment, and a history of alcohol abuse (Neerland et al., 2015). While these may not represent the only medical or neurological risk factors contributing to delirium, they have been observed as leading contributors across a majority of studies. Nurses should therefore be aware of both common and rare conditions that may present with delirium. Using predictive models for delirium is valuable in identifying high-risk patients, enabling a proactive implementation of preventative measures and strategies (Leonard et al., 2016). Identifying risk factors also helps clinicians explain potential outcomes and the recovery process to families.

It is not easy for nurses to diagnose or even identify delirium in a patient, and this challenge has contributed to the condition's growing prevalence within hospital settings. Although one might expect that patients in the intensive care unit would be more readily diagnosed — given the higher nurse-to-patient ratio and closer observation — research has shown that a majority of ICU patients suffering from delirium are not recognized as such by their nurses (Smulter et al., 2015). This points to a fundamental knowledge gap, as described by Guenther, Riedel, and Radtke (2016). A study examining why nurses fail to diagnose delirium found that years of experience was a significant factor: while many younger, less experienced nurses were aware of the condition, they found it difficult or impossible to identify in their patients. Nursing knowledge of delirium is largely acquired through experience rather than formal training (Korc-Grodzicki et al., 2015). If nurses in controlled ICU settings struggle to diagnose delirium, identifying the condition in emergency department settings presents an even greater challenge. Many elderly patients brought to a hospital may be suffering from delirium (Smulter et al., 2015), but without adequate training, nurses and clinicians often treat other underlying conditions instead.

In many hospitals, there are no standardized screening tools available for nurses to detect delirium, compounding the problem further. The CAM assessment tool has been shown to be effective in diagnosing delirium in elderly patients, and early detection makes the condition much more manageable, potentially reducing or eliminating its associated mortality (Nydahl et al., 2017). Poor communication within hospital settings may also contribute to the knowledge gap; since delirium is not well-known to patients or families, nurses may not think to screen for it during initial patient assessments. Moreover, because delirium can be triggered by a wide range of conditions, it is vital that nurses understand its etiology before prescribing or administering any medication (Smulter et al., 2015). Despite the CAM being relatively straightforward to administer, most nurses are not trained in its use. Increased training in the use of delirium screening tools is therefore essential for improving both prevention and treatment outcomes.

Conclusion

There are numerous gaps in the literature regarding delirium. A majority of research has focused on delirium within the ICU, which has led many to believe that the condition only occurs under special hospitalized conditions. However, the evidence presented in this review makes clear that delirium primarily affects elderly individuals across a wide range of settings and is frequently difficult to diagnose — a difficulty that makes the condition particularly dangerous. Early detection enables delirium to be managed effectively and can dramatically reduce its associated mortality. It is therefore recommended that most elderly patients be assessed for delirium, particularly when they present with symptoms consistent with the condition.

The gaps in the literature are likely a primary driver of limited nursing knowledge. Because delirium is not widely understood as a condition that can occur outside of hospitalization, nurses are frequently not vigilant for it when a patient presents to the hospital. As demonstrated in the reviewed literature, delirium is multifactorial — caused by a combination of factors — which further complicates diagnosis. Some underlying conditions are believed to cause delirium, while other researchers suggest that delirium may itself cause those conditions; the causal relationship is not yet fully established. What is clear, however, is that a patient presenting with symptoms consistent with delirium should be treated as having delirium until there is evidence to the contrary — a recommendation supported by most of the researchers cited in this review.

The overarching recommendation of this paper is to increase nursing knowledge of delirium so that nurses are equipped to identify the condition through a straightforward question-and-answer process with patients and their caregivers. With adequate knowledge, nurses would be better positioned to recognize when a patient may be vulnerable to delirium and to take timely action. A nurse who suspects delirium can then refer the patient for further testing to confirm or rule out the diagnosis, ultimately contributing to reduced mortality and improved patient outcomes. Improving health care for older adults, including enhanced recognition of delirium, remains a global health priority.