Magnitude of the Problem

Dementia is a prevalent condition in the hip fracture population. A recent meta-analysis of 34 studies published up to June 2009 found that the estimated prevalence of dementia in the literature pertaining to hip fracture is 19.2% (95% confidence interval, 11.4%–30.6%).

Furthermore, individuals with dementia are more likely to fall, are more likely to fall repeatedly, and have a higher likelihood of sustaining a fracture secondary to fall, even when the number of falls are controlled for. The reasons for this are likely multifactorial. Formiga and colleagues showed that patients presenting with both hip fracture and dementia were more likely to have an intrinsic cause of fall, whereas those without dementia were more likely to have fallen secondary to extrinsic causes. This finding may be at least partially explained by cognitive impairment of patients with dementia, which results in gait disturbances. Studies have shown gait disturbances in patients with early executive function impairment. In a recent 5-year prospective cohort study of 256 patients, investigators showed that even in the absence of dementia, early impairment in executive function was able to predict fall risk. Furthermore, certain medications that patients with dementia are prescribed, such as anticholinergics, are also likely to precipitate syncope, falls, and hip fracture.

In the context of hip fractures, dementia is relevant preoperatively as both a risk factor and a predictor of eventual outcome. Arguably, no conclusive evidence shows that dementia is acquired postoperatively, as recently summarized in a systematic review by Newman and colleagues.

Diagnosis and Clinical Presentation

The diagnosis of dementia is clinical, with supplementary laboratory and imaging investigations required for workup of secondary potentially treatable causes. The diagnostic workup generally entails a clinical diagnosis of dementia, a thorough investigation for underlying causes of dementia, and the identification and management of contributory comorbidities. The clinical diagnosis typically involves the use of brief cognitive tests, such as the Mini-Mental State Examination (MMSE), the Modified MMSE, or the Montreal Cognitive Assessment tool, to screen for cognitive impairment. These tools, among others, are fairly sensitive and specific in differentiating moderate dementia from normal cognitive function. However, they perform less than ideally in differentiating the milder forms of dementia and cognitive impairment. Therefore, full neuropsychological testing is indicated in patients in whom mild dementia or cognitive impairment is suspected. Validated criteria, such as those presented in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), are then applied to consolidate the diagnosis.

A more comprehensive description and approach to the clinical presentation and diagnosis of dementia are beyond the scope of this review and readers are referred to other publications.

Outcomes

Although it is well established that individuals with cognitive impairment and dementia are at increased risk of falls and fracture, whether these patients do worse when other comorbidities are controlled for in the short and long term after hip fracture is uncertain.

In a cohort of 348 patients studied retrospectively, Harboun and colleagues found that patients with dementia are more likely to be institutionalized in the 3 years after a hip fracture than those who have not sustained a hip fracture.

Muir and Yohannes performed a systematic review of the literature, which comprised 10 prospective cohort studies and 1 randomized controlled trial. Meta-analysis was not possible because of heterogeneity of outcomes. Studies included in this systematic review were evaluated to be of poor methodological quality. Sample sizes ranged from 48 to 320. The authors summarized findings pertaining to postfracture functional activity, length of stay, and discharge destination. No conclusive differences were evident in these studies between patients with and without prefracture dementia.

Patients with dementia at admission are more likely to develop delirium postoperatively. The evidence and implications of this are discussed later in the Delirium section.

Overall, the postfracture implications of dementia have not been well elucidated in the scientific literature. Studies have generally been few in number and small in size, and lack standardization to allow for meta-analysis.

Prevention

As dementia is a chronic condition, prevention of dementia per se in the period immediately preceding hip fracture is not possible. In this context, preventive efforts pertaining to hip fracture involve preventing falls and subsequent fractures in this population.

Understanding factors leading to falls in patients with dementia is crucial to circumvention. Eriksson and colleagues described the circumstances surrounding falls in patients with dementia on a psychogeriatric ward. They found no difference between the frequency of falls between day and night, although night falls were more likely to be unwitnessed. In terms of characteristics of the fall events, falls at night occurred more frequently off a platform, such as a chair or bed. Therefore, they were more likely to occur in the patient’s room. Day falls were more likely to occur in a location outside the patient’s room, such as a dining room or an activity area. Anxiety, darkness, and not wearing shoes were other risk factors for falls. In terms of characteristics of the patients, men were more likely to fall than women, and these falls were more likely to be associated with a delirious episode. When women fell, they were more likely to have an associated urinary tract infection than men. Given the nature of the study, causal mechanisms were impossible to identify.

The use of hip protectors is one intervention that has been studied as a possible means to prevent hip fracture secondary to fall. A recent prospective cohort study showed a lower rate of hip fractures among patients with dementia who wore hip protectors (relative risk, 5.63; number needed to treat, 28; P = .007). However, the effectiveness of hip protectors in the community and institutional setting has been controversial, because several studies have not shown a benefit. One study postulated that the lack of efficacy is predominantly secondary to a compliance issue. In this study by Garfinkel and colleagues, compliance criteria were strict in an institutional setting, which probably contributed to the observed positive outcome. Therefore, hip protectors may be protective given appropriate patient and setting selection to ensure adequate compliance, although making a firm suggestion in this regard is still controversial. Randomized trials are needed to definitively inform the effect of this intervention.

Overall, evidence is insufficient to make any evidence-based recommendations regarding fall prevention in the dementia population. Optimal fall prevention strategies for patients with dementia are not well elaborated and further research is needed.

Treatment and Rehabilitation

After a hip fracture, one of the earliest and most important interventions that can be used is the relief of pain through adequate analgesia. Adequate pain control should be considered fundamental to the care of all patients with hip fractures, both as a moral and compassionate responsibility and because it can prevent secondary complications, such as the development of delirium. Unfortunately, pain control in patients with dementia is too frequently suboptimal despite evidence that these patients do experience pain. A prospective study by Morrison and colleagues comparing 59 cognitively intact patients with 38 patients experiencing dementia found that the latter group received one-third of the morphine sulfate equivalent as the former group. Most patients in either group did not receive a standing order for pain medication (arguably more important in patients with advanced dementia). Part of the issue may be that health care personnel, such as nurses, are not adequately trained at assessing pain in patients with dementia. Strategies could be considered, such as regular administration as opposed to as-needed administration.

A nonblinded randomized controlled trial of 260 independent community-living patients in Finland was conducted to determine whether a specialized geriatric rehabilitation team consisting of physicians, nurses, and allied health professionals could impact length of stay, mortality, and place of residence at 3 months and 1 year. An unequal distribution was seen based on MMSE scores postrandomization, and subgroup analyses were undertaken of the patients with and without low MMSE scores. Patients with hip fractures with mild to moderate dementia who received the intervention showed decreased length of stay and returned to independent community living at 3 months compared with controls. However, the significant difference did not persist at 1-year follow-up. The trial was not able to detect a significant difference in outcomes among patients with normal cognition and in those with severe dementia. Although no significant difference in mortality was detected, a trend was seen toward increasing mortality with increasing severity of dementia. This trial was certainly underpowered to detect a difference in its primary outcomes, because the a priori determined sample size of 250 was not achieved.

Patients with hip fractures who are not able to adequately regain function in the hospital are often discharged to specialized institutions for further rehabilitation. However, home-based rehabilitation is another option for community-dwelling patients with dementia after a hip fracture. In a prospective cohort study of patients with hip fractures managed operatively, Giusti and Barone followed 55 patients discharged to a rehabilitation institution and 41 patients discharged directly home postoperatively. They found that function was at least equivalent to if not superior to institution-based rehabilitation as measured by the Barthel index for Activities of Daily Living (ADLs) and the Lawson index for Instrumental ADLs.

Magnitude of the Problem

Delirium is a condition especially prevalent in hospitalized patients. In certain hospital settings, its incidence is particularly marked. Next to patients admitted to the intensive care unit, postoperative patients and those with hip fractures are considered to be among those at the highest at risk for delirium.

In regard to hip fracture, a meta-analysis of studies to 2005 showed a variable prevalence of delirium as reported in the orthopedic literature, ranging from 4.0% to 53.3%, with a pooled effect size of 21.7%. Consistently across studies, patients with hip fractures tended to have higher rates of postoperative delirium than those undergoing elective orthopedic surgery. Up to 35% of delirium cases were shown to have preoperative onset, a large proportion of which persisted postoperatively.

Risk Factors and Causes

The pathophysiologic cause of delirium, although not completely understood, has been postulated to involve preexisting cerebral compromise secondary to aging or an underlying condition such as dementia. Subsequent insults by noxious external exposures result in further compromise and lead to the clinical manifestations of the delirious state. In accordance with this theory, clinical studies have generally attempted to elucidate patients at increased risk for delirium (preexisting compromise) or the external exposures that precipitate an episode of delirium.

In an exploratory study, Juliebo and colleagues studied many potential variables for possible predictive value of both preoperative and postoperative delirium. The investigators found that both precognitive impairment and sustaining an injury in an indoor environment were significantly more common in patients who developed delirium in hospital. Fever and lengthier waits for surgery were significantly correlated with preoperative delirium, whereas low body mass index (BMI) was significantly correlated with postoperative delirium. Because conclusions of causation or mechanism are impossible given the exploratory nature of this study, these results warrant further study.

In a prospective cohort study of 425 patients with hip fracture, Lee and colleagues found that the risk factors for delirium were most relevant in the absence of dementia. Patients with dementia were at increased risk of developing delirium regardless of other risk factors (54% vs 26%; P <.001). Patients without dementia who were at increased risk of perioperative delirium were of advancing age (as a continuous variable), male sex, or low BMI, or had an operative time longer than 2 hours. Therefore, the authors noted that risk stratification must initially involve an assessment of preoperative cognitive status. This finding has been corroborated in other studies.

Brauer and colleagues had 571 cases reviewed by 2 physicians prospectively to determine precipitating causes of delirium. With well-defined prespecified diagnostic criteria, they were unable to determine a definitive cause of delirium in most cases. However, they did identify various factors that seemed to contribute to the development of postoperative delirium. Most commonly identified factors were sensory/environmental, infection, drugs, and fluid and electrolyte abnormalities.

Furlaneto and Garcez-Leme more recently identified these same causative agents in the development of delirium in patients with hip fractures. However, in contrast to the study by Brauer and colleagues, these investigators were able to identify a single underlying cause in most cases. However, a key limitation to this conclusion was that prespecified criteria for diagnosis were not defined. Therefore, their conclusions require cautious interpretation.

Diagnosis and Clinical Presentation

A diagnosis of delirium is made clinically at the bedside, with laboratory and imaging investigations supplementing the diagnosis through identifying an underlying correctable cause or ruling out other suspected diagnoses. The diagnosis is made when a patient meets accepted diagnostic criteria, such as those outlined by the DSM-IV ( Box 1 ). Various assessment tools have been devised to assist with rapid assessment and diagnosis. Among these, the Confusion Assessment Method instrument is most widely used and has a high sensitivity and specificity for diagnosing delirium. The MMSE has less than ideal sensitivity and specificity for diagnosing delirium. Other instruments are available that rate the severity of dementia. These instruments are used frequently in research studies but rarely in the clinical setting.

Box 1

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