Frailty in younger adults in hospital

BACKGROUND

Even though frailty has been extensively measured in the acute care setting, relatively little is known about the frailty of younger adult inpatients.

AIM

This study aimed to measure frailty in a sample of hospitalized adults aged 18 years and over and to examine how frailty in younger adult inpatients differs from middle-aged and older adult inpatients.

DESIGN

Secondary analyses of prospectively collected cohort data.

METHODS

Research nurses assessed 910 patients at admission to four Australian hospitals using the interRAI Acute Care instrument. Comparison of frailty index (FI) scores and domains was conducted across three age groups: younger (18-49 years), middle-aged (50-69 years) and older adults (≥70 years). Multivariable logistic regression examined risk of prolonged length of stay and unfavourable discharge destination.

RESULTS

Younger adults (n = 214; 23.5%) had a mean (SD) FI of 0.19 (0.10). Approximately 27% (n = 57) of younger adults were frail (FI > 0.25). Mood and behaviour, health symptoms and syndromes, nutrition and pain were the most frequently affected domains in younger adults and 50% had ≥3 comorbidities. Frailty increased the risk of long length of stay (odds ratio (OR) = 1.77, P < 0.001) but not the risk of an unfavourable discharge (OR = 1.40, P = 0.20) in younger adults.

CONCLUSIONS

This study showed that frailty is prevalent in younger patients admitted to acute care and is associated with adverse outcomes. This study was a critical first step towards establishing an understanding of frailty in younger hospitalized adults.

Study protocol for The GOAL Trial: comprehensive geriatric assessment for frail older people with chronic kidney disease to increase attainment of patient-identified goals-a cluster randomised controlled trial

BACKGROUND

An increasing number of older people are living with chronic kidney disease (CKD). Many have complex healthcare needs and are at risk of deteriorating health and functional status, which can adversely affect their quality of life. Comprehensive geriatric assessment (CGA) is an effective intervention to improve survival and independence of older people, but its clinical utility and cost-effectiveness in frail older people living with CKD is unknown.

METHODS

The GOAL Trial is a pragmatic, multi-centre, open-label, superiority, cluster randomised controlled trial developed by consumers, clinicians, and researchers. It has a two-arm design, CGA compared with standard care, with 1:1 allocation of a total of 16 clusters. Within each cluster, study participants ≥ 65 years of age (or ≥ 55 years if Aboriginal or Torres Strait Islander (First Nations Australians)) with CKD stage 3-5/5D who are frail, measured by a Frailty Index (FI) of > 0.25, are recruited. Participants in intervention clusters receive a CGA by a geriatrician to identify medical, social, and functional needs, optimise medication prescribing, and arrange multidisciplinary referral if required. Those in standard care clusters receive usual care. The primary outcome is attainment of self-identified goals assessed by standardised Goal Attainment Scaling (GAS) at 3 months. Secondary outcomes include GAS at 6 and 12 months, quality of life (EQ-5D-5L), frailty (Frailty Index - Short Form), transfer to residential aged care facilities, cost-effectiveness, and safety (cause-specific hospitalisations, mortality). A process evaluation will be conducted in parallel with the trial including whether the intervention was delivered as intended, any issue or local barriers to intervention delivery, and perceptions of the intervention by participants. The trial has 90% power to detect a clinically meaningful mean difference in GAS of 10 units.

DISCUSSION

This trial addresses patient-prioritised outcomes. It will be conducted, disseminated and implemented by clinicians and researchers in partnership with consumers. If CGA is found to have clinical and cost-effectiveness for frail older people with CKD, the intervention framework could be embedded into routine clinical practice. The implementation of the trial's findings will be supported by presentations at conferences and forums with clinicians and consumers at specifically convened workshops, to enable rapid adoption into practice and policy for both nephrology and geriatric disciplines. It has potential to materially advance patient-centred care and improve clinical and patient-reported outcomes (including quality of life) for frail older people living with CKD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04538157. Registered on 3 September 2020.

How frail is frail? A systematic scoping review and synthesis of high impact studies

AIMS

While the frailty index (FI) is a continuous variable, an FI score of 0.25 has construct and predictive validity to categorise community-dwelling older adults as frail or non-frail. Our study aimed to explore which FI categories (FI scores and labels) were being used in high impact studies of adults across different care settings and why these categories were being chosen by study authors.

METHODS

For this systematic scoping review, Medline, Cochrane and EMBASE databases were searched for studies that measured and categorised an FI. Of 1314 articles screened, 303 met the eligibility criteria (community: N = 205; residential aged care: N = 24; acute care: N = 74). For each setting, the 10 studies with the highest field-weighted citation impact (FWCI) were identified and data, including FI scores and labels and justification provided, were extracted and analysed.

RESULTS

FI scores used to distinguish frail and non-frail participants varied from 0.12 to 0.45 with 0.21 and 0.25 used most frequently. Additional categories such as mildly, moderately and severely frail were defined inconsistently. The rationale for selecting particular FI scores and labels were reported in most studies, but were not always relevant.

CONCLUSIONS

High impact studies vary in the way they categorise the FI and while there is some evidence in the community-dweller literature, FI categories have not been well validated in acute and residential aged care. For the time being, in those settings, the FI should be reported as a continuous variable wherever possible. It is important to continue working towards defining frailty categories as variability in FI categorisation impacts the ability to synthesise results and to translate findings into clinical practice.

The Utility of the Frailty Index in Clinical Decision Making

Using clinical vignettes, this study aimed to determine if a measure of patient frailty would impact management decisions made by geriatricians regarding commonly encountered clinical situations. Electronic surveys consisting of three vignettes derived from cases commonly seen in an acute inpatient ward were distributed to geriatricians. Vignettes included patients being considered for intensive care treatment, rehabilitation, or coronary artery bypass surgery. A frailty index was generated through Comprehensive electronic Geriatric Assessment. For each vignette, respondents were asked to make a recommendation for management, based on either a brief or detailed amount of clinical information and to reconsider their decision after the addition of the frailty index. The study suggests that quantification of frailty might aid the clinical judgment now employed daily to proceed with usual care, or to modify it based on the vulnerability of the person to whom it is aimed.

Do sex differences in chronic disease underpin the sex-frailty paradox?

The 'male-female health-survival paradox' is a well-described clinical phenomenon. More recently, it has been conceptualized as a 'sex-frailty paradox': females may be considered to be more frail (because they have poorer health status) but also less frail (because they are less vulnerable to death) than males of the same age. Here, we review potential biological, behavioral and social mechanisms underpinning sex differences in morbidity, mortality and frailty before considering the question at the center of the sex paradox - why is it that females are able to tolerate poor health better than males? We explore, in detail, a frequently cited explanation for the sex paradox that centers on sex differences in chronic disease and conclude by presenting a new approach to this old hypothesis.

Do health assets have a protective effect for hospitalized frail older adults?

BACKGROUND

Although increasing frailty is predictive of increased mortality and length of stay for hospitalized older adults, this approach ignores health assets that individuals can utilize to recover following hospital admission.

AIM

To examine whether health assets mitigate the effect of frailty on outcomes for older adults admitted to hospital.

DESIGN

Patients of 1418 aged ≥ 70 years admitted to 11 hospitals in Australia were evaluated at admission using the interRAI assessment system for Acute Care, which surveys a large number of domains, including cognition, communication, mood and behaviour, activities of daily living, continence, nutrition, skin condition, falls and medical diagnosis.

METHODS

The data set was interrogated for potential health assets and a multiple logistic regression adjusted for frailty index, age and gender as covariates was performed for the outcomes mortality, length of stay, re-admission and new need for residential care.

RESULTS

Inpatient mortality was 3% and 4.5% of patients died within 28 days of discharge. Median length of stay was 7 days (IQR 4-11). In multivariate analysis that includes frailty, being able to walk further [OR 0.08 (0.01-0.63)], ability to leave the house [OR 0.35 (0.17-0.74)] and living alone [OR 0.28 (0.10-0.79)] were protective against mortality. The presence of a support person was associated with a decreased length of stay [OR 0.14 (0.08-0.25)].

CONCLUSION

The inclusion of health assets in predictive models can improve prognostication and highlights potential interventions to improve outcomes for hospitalized older adults.

Validation of a frailty index in older cancer patients with solid tumours

Background

Frailty is an indicator of physiological reserve in older people. In non-cancer settings, frailty indices are reliable predictors of adverse health outcomes. The aims of this study were to 1) derive and validate a frailty index (FI) from comprehensive geriatric assessment (CGA) data obtained in the solid tumour chemotherapy setting, and 2) to explore whether the FI-CGA could predict chemotherapy decisions and survival in older cancer patients with solid tumours.

Methods

Prospective cohort study of a consecutive series sample of 175 cancer patients aged 65 and older with solid tumours. A frailty index was calculated using an accumulated deficits model, coding items from the comprehensive geriatric assessment tool administered prior to chemotherapy decision-making. The domains of physical and cognitive functioning, nutrition, mood, basic and instrumental activities of daily living, and comorbidities were incorporated as deficits into the model.

Results

The FI-CGA had a right-skewed distribution, with median (interquartile range) of 0.27 (0.21–0.39). The 99% limit to deficit accumulation was below the theoretical maximum of 1.0, at 0.75. The FI-CGA was significantly related (p < 0.001) to vulnerability as assessed by the Vulnerable Elders Survey-13 and to medical oncologists’ assessments of fitness or vulnerability to treatment. Baseline frailty as determined by the FI-CGA was also associated with treatment decisions (Treatment Terminated, Treatment Completed, No Planned Treatment) (p < 0.001), with the No Planned Treatment group significantly frailer than the other two groups.

Conclusion

The FI-CGA is a potentially useful adjunct to cancer clinical decision-making that could predict chemotherapy outcomes in older patients with solid tumours.

Perioperative Assessment of Older Surgical Patients using a Frailty Index—Feasibility and Association with Adverse Postoperative Outcomes

This study aimed to examine the feasibility of using a frailty index (FI) based on comprehensive geriatric assessment (CGA), to assess the level of frailty in older surgical patients preoperatively and to evaluate the association of FI-CGA with poorer postoperative outcomes. Two hundred and forty-six patients aged ≥70 years undergoing intermediate- to high-risk surgery in a tertiary hospital were recruited. Frailty was assessed using a 57-item FI-CGA form, with fit, intermediate frail, and frail patients defined as FI ≥0.25, >0.25 to 0.4, and >0.4, respectively. Adverse outcomes were ascertained at 30 days and 12 months post-surgery. Logistic regression models assessed the relationship between FI and adverse outcomes, adjusting for age, gender and acuity of surgery. The mean age of the participants was 79 years (standard deviation [SD] 6.5%), 52% were female, 91% were admitted from the community, 43% underwent acute surgery, and 19% were assessed as frail. The FI-CGA form was reported as being easy to apply, with a low patient refusal rate (2.2%). The majority of items were easy to rate, although inter-rater reliability was not tested. In relation to outcomes, greater frailty was associated with increased 12-month mortality (6.4%, 15.6%, and 23% for fit, intermediate frail, and frail patients respectively, P=0.01) and 12-month hospital readmission (33.9%, 48.9%, and 60% respectively, P=0.004). There were no statistically significant differences between fit, intermediate frail, and frail groups in perioperative adverse events (17.4%, 23.3%, and 19.1% respectively, P=0.577) or 30-day postoperative complications (35.8%, 47.8%, and 46.8% respectively, P=0.183). Our findings suggest that it is feasible to use the FI-CGA to assess frailty preoperatively, and that using the FI-CGA may identify patients at high risk of adverse long-term outcomes.

Sex differences in frailty: A systematic review and meta-analysis

BACKGROUND

It is a well-described clinical phenomenon that females live longer than males, yet tend to experience greater levels of co-morbidity and disability. Females can therefore be considered both more frail (because they have poorer health status) and less frail (because they have a lower risk of mortality). This systematic review aimed to determine whether this ageing paradox is demonstrated when the Frailty Index (FI) is used to measure frailty.

METHODS

Medline, EMBASE and CINAHL databases were searched for observational studies that measured FI and mortality in community-dwellers over 65years of age. In five-year age groups, meta-analysis determined the sex differences in mean FI (MD=mean FI_female-mean FI_male) and mortality rate.

RESULTS

Of 6482 articles screened, seven articles were included. Meta-analysis of data from five studies (37,426 participants) found that MD values were positive (p<0.001; MD range=0.02-0.06) in all age groups, indicating that females had higher FI scores than males at all ages. This finding was consistent across individual studies. Heterogeneity was high (I²=72.7%), reflecting methodological differences. Meta-analysis of mortality data (13,127 participants) showed that male mortality rates exceeded female mortality rates up until the 90 to 94-years age group. Individual studies reported higher mortality for males at each level of FI, and higher risk of death for males when controlling for age and FI.

CONCLUSIONS

The pattern of sex differences in the FI and mortality of older adults was consistent across populations and confirmed a 'male-female health-survival paradox'.

Frailty and post-operative outcomes in older surgical patients: a systematic review

Background

As the population ages, increasing numbers of older adults are undergoing surgery. Frailty is prevalent in older adults and may be a better predictor of post-operative morbidity and mortality than chronological age. The aim of this review was to examine the impact of frailty on adverse outcomes in the ‘older old’ and ‘oldest old’ surgical patients.

Methods

A systematic review was undertaken. Electronic databases from 2010 to 2015 were searched to identify articles which evaluated the relationship between frailty and post-operative outcomes in surgical populations with a mean age of 75 and older. Articles were excluded if they were in non-English languages or if frailty was measured using a single marker only. Demographic data, type of surgery performed, frailty measure and impact of frailty on adverse outcomes were extracted from the selected studies. Quality of the studies and risk of bias was assessed by the Epidemiological Appraisal Instrument.

Results

Twenty-three studies were selected for the review and they were assessed as medium to high quality. The mean age ranged from 75 to 87 years, and included patients undergoing cardiac, oncological, general, vascular and hip fracture surgeries. There were 21 different instruments used to measure frailty. Regardless of how frailty was measured, the strongest evidence in terms of numbers of studies, consistency of results and study quality was for associations between frailty and increased mortality at 30 days, 90 days and one year follow-up, post-operative complications and length of stay. A small number of studies reported on discharge to institutional care, functional decline and lower quality of life after surgery, and also found a significant association with frailty.

Conclusion

There was strong evidence that frailty in older-old and oldest-old surgical patients predicts post-operative mortality, complications, and prolonged length of stay. Frailty assessment may be a valuable tool in peri-operative assessment. It is possible that different frailty tools are best suited for different acuity and type of surgical patients. The association between frailty and return to pre-morbid function, discharge destination, and quality of life after surgery warrants further research.

Impact of Post-Acute Transition Care for Frail Older People: A Prospective Study

OBJECTIVES

To describe the characteristics and outcomes of frail older people in a post-acute transitional care program and to compare the recovery trajectories of patients with high and low care needs to determine who benefits from transition care.

DESIGN

Prospective observational cohort.

PARTICIPANTS AND SETTING

351 patients admitted to community-based transition care in two Australian states during an 11 month recruitment period.

INTERVENTION

Transition care provides a package of services including personal care, physiotherapy and occupational therapy, nursing care and case management post discharge from hospital. It is targeted at frail older people who, in the absence of an alternative, would otherwise be eligible for admission to residential aged care.

MEASUREMENTS

A comprehensive geriatric assessment using the interRAI Home Care instrument was conducted at transition care admission and discharge. Primary outcomes included changes in functional ability during transition care, living status at discharge and six months follow-up, and hospital re-admissions over the follow-up period. For comparison of outcomes, the cohort was divided into two groups based on risk factors for admission to high or low-level residential aged care.

RESULTS

There were no significant differences between groups on outcomes, with over 85% of the cohort living in the community at follow-up. More than 80% of the cohort showed functional improvement or maintenance of independence during transition care, with no significant differences between the groups.

CONCLUSIONS

Post-acute programs should not be targeted solely at fitter older people: those who are frail also have the potential to gain from community-based rehabilitation.

Feasibility of Using Information Derived from a Care Partner to Develop a Frailty Index Based on Comprehensive Geriatric Assessment

BACKGROUND

Frailty is a state of increasing vulnerability that places an individual at high risk for adverse health outcomes. The best approach for frailty measurement in clinical practice has not been resolved. Frailty can be measured by deficit accumulation and be derived from a comprehensive geriatric assessment (CGA). In busy clinical practice, it may not be feasible to gather this information entirely from patients, particularly from those with cognitive decline.

OBJECTIVE

We describe the feasibility of a frailty index based upon a care partner derived CGA (CP-CGA). In addition, we sought to establish the acceptability of the questionnaire and explore whether care partners felt that the provided information contribute to patient assessment.

DESIGN AND SETTING

A cross-sectional data analysis of 99 community dwelling older adults attending geriatric ambulatory care clinics at a single tertiary care center.

MEASUREMENTS

Care partners completed the CP-CGA and a Clinical Frailty Scale (CFS; Range 1 -Very fit- to 9 -Terminally ill). We evaluated the time to complete and item completeness.

RESULTS

The mean age of patients was 81.3±5.7 years. Most were women (n=54), widowed, lived in their own home, with a median CFS of 5 (Mildly Frail). The care partner respondent was usually an offspring. Item completeness was 95% with a mean time to complete of 15.5±8.6 minutes.

CONCLUSION

The CP-CGA seems feasible for gathering information that would be integral towards determining frailty by deficit accumulation. Future inquiries will evaluate its feasibility in other settings and validity as a form of frailty assessment.

Baseline Vulnerability and Inpatient Frailty Status in Relation to Adverse Outcomes in a Surgical Cohort

This study aimed to derive measures of baseline vulnerability and inpatient frailty in elderly surgical patients and to study their association with adverse post-operative outcomes. Data from comprehensive geriatric assessment of 208 general surgical and orthopaedic patients aged 70 and over admitted to four acute hospitals in Queensland, Australia, were analysed to derive a baseline and inpatient Frailty Index (FI). The association of these indices with adverse outcomes was examined in logistic regression. The mean (SD) baseline FI was 0.19 (0.09) compared to 0.26 (0.12) on admission, with a predominant increase in domains related to functional status. Both baseline and inpatient FI were significant predictors of one year mortality, inpatient delirium, and a composite adverse outcome, after adjusting for age, sex and acuity of surgery. In summary, detecting baseline frailty pre-hospitalisation may be useful to trigger the implementation of supportive and preventative measures in hospital.

Prescribing for older people discharged from the acute sector to residential aged-care facilities

For frail older people, admission to hospital is an opportunity to review the indications for specific medications. This research investigates prescribing for 206 older people discharged into residential aged care facilities from 11 acute care hospitals in Australia. Patients had multiple comorbidities (mean 6), high levels of dependency, and were prescribed a mean of 7.2 regular medications at admission to hospital and 8.1 medications on discharge, with hyper-polypharmacy (≥10 drugs) increasing from 24.3% to 32.5%. Many drugs were preventive medications whose time until benefit was likely to exceed the expected lifespan. In summary, frail patients continue to be exposed to extensive polypharmacy and medications with uncertain risk-benefit ratio.

A pragmatic triage system to reduce length of stay in medical emergency admission: feasibility study and health economic analysis

BACKGROUND

Departments of Internal Medicine tend to treat patients on a first come first served basis. The effects of using triage systems are not known.

METHODS

We studied a cohort in an Acute Medical Unit (AMU). A computer-assisted triage system using acute physiology, pre-existing illness and mobility identified five distinct risk categories. Management of the category of very low risk patients was streamlined by a dedicated Navigator. Main outcome parameters were length of hospital stay (LOS) and overall costs. Results were adjusted for the degree of frailty as measured by the Clinical Frailty Scale (CFS). A six month baseline phase and intervention phase were compared.

RESULTS

6764 patients were included: 3084 in the baseline and 3680 in the intervention phase. Patients with very low risk of death accounted for 40% of the cohort. The LOS of the 1489 patients with very low risk of death in the intervention group was reduced by a mean of 1.85days if compared with the 1276 patients with very low risk in the baseline cohort. This was true even after adjustment for frailty. Over the six month period the cost of care was reduced by £250,158 in very low patients with no increase in readmissions or 30day mortality.

CONCLUSIONS

Implementation of an advanced triage system had a measurable impact on cost of care for patients with very low risk of death. Patients were safely discharged earlier to their own home and the intervention was cost-effective.

Patient frailty: the elephant in the operating room

For most surgeons and many anaesthetists, patient frailty is currently the 'elephant in the (operating) room': it is easy to spot, but is often ignored. In this paper, we discuss different approaches to the measurement of frailty and review the evidence regarding the effect of frailty on peri-operative outcomes. We explore the limitations of 'eyeballing' patients to quantify frailty, and consider why the frail older patient, challenged by seemingly minor insults in the postoperative period, may suffer falls or delirium. Frailty represents a state of increased vulnerability to stressors, and older inpatients are exposed to multiple stressors in the peri-operative setting. Quantifying frailty is likely to increase the precision of peri-operative risk assessment. The Frailty Index derived from Comprehensive Geriatric Assessment is a simple and robust way to quantify frailty, but is yet to be systematically investigated in the pre-operative setting. Furthermore, the optimal care for frail patients and the reversibility of frailty with prehabilitation are fertile areas for future research.

Frailty: a key indicator to minimize inappropriate medication in older people

Older populations are more likely to have multiple co-morbid diseases that require multiple treatments, which make them a large consumer of medications. As a person grows older, their ability to tolerate medications becomes less due to age-related changes in pharmacokinetics and pharmacodynamics often heading along a path that leads to frailty. Frail older persons often have multiple co-morbidities with signs of impairment in activities of daily living. Prescribing drugs for these vulnerable individuals is difficult and is a potentially unsafe activity. Inappropriate prescribing in older population can be detected using explicit (criterion-based) or implicit (judgment-based) criteria. Unfortunately, most current therapeutic guidelines are applicable only to healthy older adults and cannot be generalized to frail patients. These discrepancies should be addressed either by developing new criteria or by refining the existing tools for frail older people. The first and foremost step is to identify the frail patient in clinical practice by applying clinically validated tools. Once the frail patient has been identified, there is a need for specific measures or criteria to assess appropriateness of therapy that consider such factors as quality of life, functional status and remaining life expectancy and thus modified goals of care.

Frailty in older inpatients: what physicians need to know

Physicians involved in the care of medical inpatients, irrespective of their sub-specialty area, will be responsible for the management of a significant number of older adults with complex care needs and multiple co-morbidities. These patients are vulnerable to poor outcomes (including falls, institutionalization and death)--a vulnerability often linked with the term 'frail' or 'frailty'. Frailty is associated with advanced chronological age and chronic disease but is a separate construct. The measurement of frailty has received significant attention in recent geriatric medicine literature, with various models proposed to predict the risk of poor outcomes. Here, we briefly review different approaches to the definition of frailty, focusing on the conceptualization of frailty as the failure of a complex system. We explore how falls, a common cause of morbidity and mortality in older patient groups, may be a manifestation of increasing frailty and argue that falls services should avoid the practice of pursuing a single-organ cause when there are likely to be several contributing factors at play. We also consider the impact of frailty on medication prescribing and discuss how individualized prescribing could reduce the risk of adverse drug reactions in at-risk older inpatients. While it can be frustrating for physicians to manage patients who do not fit well into disease-based diagnostic and management algorithms, understanding frailty has the potential to improve the clinical care of vulnerable older people in the hospital setting.

Income and the midlife peak in common mental disorder prevalence

BACKGROUND

The prevalence of psychological distress and common mental disorders has been shown to peak in midlife but analyses have ignored the association of poor material circumstances with prevalence. This study aimed to test the hypothesis that the midlife prevalence peak occurs only in lower-income households.

METHOD

Pooled data were used from the annual Health Survey for England, a nationally representative cross-sectional study, on community-dwelling individuals aged ≥ 16 years from years 1997 to 2006 (n=100 457). 12-item General Health Questionnaire scores, reported mental illness diagnoses and receipt of relevant medication were assessed in relation to household income and age. Analyses were separated by gender and adjusted for age, ethnicity, smoking, social class, education and co-morbidities.

RESULTS

Prevalence of psychological distress, diagnoses and treatments rose with age until early middle age and declined subsequently. In analyses conducted separately by income categories, this pattern was marked in low-income groups but absent in high-income groups. Income-related inequalities in the prevalence of psychological distress were greatest in midlife; for example, in men aged 45-54 years the odds ratio of receiving psychiatric medication in the lowest income group compared with the highest was 7.50 [95% confidence interval (CI) 4.24-13.27] and in women aged 45-54 years the odds ratio of reporting mental illness was 10.25 (95% CI 6.16-17.05).

CONCLUSIONS

An increased prevalence of psychological distress, common mental disorder diagnoses and treatment in midlife is not a universal phenomenon but is found only in those in low-income households. This implies the phenomenon is not inevitable but is potentially manageable or preventable.

Hospital use, institutionalisation and mortality associated with delirium

BACKGROUND

Delirium is a disorder affecting consciousness, which gives rise to core clinical features and associated symptoms. Older patients are particularly prone, owing to higher rates of pre-existing cognitive impairment, frailty, co-morbidity and polypharmacy.

OBJECTIVES

The aim of this study was to investigate the hypotheses that delirium affects the most vulnerable older adults and is associated with long-term adverse health outcome.

METHODS

This prospective cohort study evaluated 278 medical patients aged > or = 75 years admitted acutely to a district general hospital in South Wales. Patients were screened for delirium at presentation and on alternate days throughout their hospital stay. Assessments also included illness severity, preadmission cognition, co-morbidity and functional status. Patients were followed for 5 years to determine rates of institutionalisation and mortality. Number of days in hospital in the 4 years prior to and 5 years after index admission were recorded.

RESULTS

Delirium was detected in 103 patients and excluded in 175. Median time to death was 162 days (interquartile range 21-556) for those with delirium compared with 1,444 days (25% mortality 435 days, 75% mortality>5 years) for those without (P < 0.001). After adjusting for multiple confounders, delirium was associated with an increased risk of death (hazard ratio range 2.0-3.5; P < or = 0.002). Institutionalisation was higher in the first year following delirium (P = 0.03). While those with delirium tended to be older with more preadmission cognitive impairment, greater functional dependency and more co-morbidity, they did not spend more days in hospital in the 4 years prior to index admission.

CONCLUSIONS

Delirium is associated with high rates of institutionalisation and an increased risk of death up to 5 years after index event. Prior to delirium, individuals seem to compensate for their vulnerability. The impact of delirium itself, directly or indirectly, may convert vulnerability into adverse outcome.

Comparison of the prognostic importance of diagnosed diabetes, co-morbidity and frailty in older people

AIMS

To compare the relative prognostic importance in older people of diagnosed diabetes, the number and severity of co-morbidities and frailty.

METHODS

Two thousand three hundred and five people aged > or = 70 years comprised the clinical examination cohort of the Canadian Study of Health and Aging. Frailty was defined as a score of > or = 5 on a 7-point Clinical Frailty Scale. The cohort was followed for 5 years.

RESULTS

Diabetes was more likely to be associated with medium-term mortality (adjusted hazard ratio (HR) 1.42; 95% confidence interval (CI) 1.20-1.69) than co-morbidity (HR 1.03; 95% CI 1.01-1.05). Frailty most strongly predicted death (HR 2.72; 95% CI 2.34-3.16). Frail older adults were 2.62 times (95% CI 1.36-5.06) more likely to have a complication of diabetes, independent of age, sex and number of years living with diabetes. People with diabetes were younger than those without (81.3 vs. 83.3 years) but a similar proportion were frail (42.2 vs.43.4%). The median life expectancy for frail older adults with diabetes was 23 months (95% CI 18-28 months).

CONCLUSIONS

In this cohort, the risk of mortality in older people was defined more precisely by a clinical measure of frailty than by diabetes or burden of co-morbidity. Those with diagnosed diabetes were younger than those without but had the same frailty status; diabetes can therefore be considered to increase 'biological age' by 2 years in those aged over 70 years. The limited life expectancy of frail older people with diabetes highlights the importance of recognizing frailty and supports the individualization of care in older people with diabetes.

Comparison of two frailty measures in the Conselice Study of Brain Ageing

OBJECTIVES

Uncertainty about the definition of frailty is reflected by the development of many ways to identify frail people. We aimed to compare the validity of two frailty measures in participants of the Conselice Study of Brain Aging.

DESIGN

Prospective population-based study with 4 year follow up.

PARTICIPANTS/SETTING

1,016 subjects aged 65 and over in a rural Italian population.

METHODS

For each participant, a Frailty Index (FI) and a Conselice Study of Brain Aging Score (CSBAS) were determined. The FI was created from 43 deficits according to a standardized methodology; 7 variables derived from a previously validated Easy Prognostic Score comprised the CSBAS.

RESULTS

The FI had characteristic properties described in other population samples, with a gamma distribution, a 99% limit of about 0.64 and higher values in women than men. CSBAS and FI were strongly correlated with each other (r = 0.72) and both correlated with age (r = 0.32, r = 0.27, respectively). Each was independently predictive of death in a multivariate model, with greater specificity and sensitivity than age alone.

CONCLUSIONS

Frailty can be measured by different tools and facilitates a more direct quantification of individual vulnerability than chronological age alone. Though the Frailty Index and the Conselice Study of Brain Aging Score are underpinned by different rationales, clinical utility will continue to motivate their development.

Effect of smoking on the accumulation of deficits, frailty and survival in older adults: a secondary analysis from the Canadian Study of Health and Aging

OBJECTIVES

Smoking has adverse effects on a variety of organ systems but little is known about the relationship between smoking and frailty. We aimed to investigate differences in health status between smoking and non smoking older adults.

DESIGN AND SETTING

The Canadian Study of Health and Aging, a nationally representative cohort study.

PARTICIPANTS

Nine thousand and eight community-dwelling men and women age 65 years and over at baseline.

MEASUREMENTS

Smoking status was determined using a Self-Assessed Risk Factor Questionnaire. Comparisons were made between never smokers, light smokers and heavy smokers with heavy smokers defined as those who smoked >or= 1 pack per day for 20 years or more. A frailty index (FI) generated from 40 self-reported health deficits was also modified to exclude 5 variables that could be directly attributed to smoking (e.g. cough). Decedent information was collected over 10 years.

RESULTS

Average FI values increased exponentially with age. For both men and women, heavy smokers were the most frail, light smokers had intermediate frailty status and never smokers were fittest. Modification of the FI did not impact these differences. Heavy smokers had significantly worse mortality than non smokers and higher rates of death in smokers persisted in the oldest old. 120 month survival curves, grouped for age, sex and smoking status showed that male smokers > 75 years had the highest mortality rates.

CONCLUSIONS

Smoking causes poorer health status at older ages which can be captured by the frailty index. Higher rates of death in smokers persist in the oldest old, with no emergence of "survivors" with fitness or longevity advantages.

Virtual screening in structure-based drug discovery

Recent advances in structure determination and computational methods have encouraged the development of structure-based virtual screening. Here we survey progress in the field and review the most recent methods, validation experiments and real applications, including an in-house example of hit identification for the oncology target Hsp90. These results provide a basis for discussing the current state of structure-based virtual screening and to outline the developments that are expected to have a major impact in the near future.

Drug-like annotation and duplicate analysis of a 23-supplier chemical database totalling 2.7 million compounds

We have implemented five drug-like filters, based on 1D and 2D molecular descriptors, and applied them to characterize the drug-like properties of commercially available chemical compounds. In addition to previously published filters (Lipinski and Veber), we implemented a filter for medicinal chemistry tractability based on lists of chemical features drawn up by a panel of medicinal chemists. A filter based on the modeling of aqueous solubility (>1 microM) was derived in-house, as well as another based on the modeling of Caco-2 passive membrane permeability (>10 nm/s). A library of 2.7 million compounds was collated from the 23 compound suppliers and analyzed with these filters, highlighting a tendency toward highly lipophilic compounds. The library contains 1.6 M unique structures, of which 37% (607,223) passed all five drug-like filters. None of the 23 suppliers provides all the members of the drug-like subset, emphasizing the benefit of considering compounds from various compound suppliers as a source of diversity for drug discovery.

Structure and mechanism of the oestrogen receptor

We have determined the structures of the oestrogen receptor ligand-binding domain in complex with a range of ligands and with fragments of co-regulator proteins. These structures provide insights into the structural mechanisms underlying the receptor's complex pharmacological properties and how the conformation of the receptor modulates its ability to recruit co-regulators that are necessary for transcriptional activation.

Structural aspects of agonism and antagonism in the oestrogen receptor

We have determined the three-dimensional structures of both alpha- and beta-forms of the ligand-binding domain of the oestrogen receptor (ER) in complexes with a range of receptor agonists and antagonists. Here, we summarize how these structures provide both an understanding of the ER's distinctive pharmacophore and a rationale for its ability to bind a diverse range of chemically distinct compounds. In addition, these studies provide a unique insight into the mechanisms that underlie receptor activation, as well as providing a structural basis for the antagonist action of molecules, such as raloxifene.

Structural insights into the mode of action of a pure antiestrogen

BACKGROUND

Estrogens exert their effects on target tissues by binding to a nuclear transcription factor termed the estrogen receptor (ER). Previous structural studies have demonstrated that each class of ER ligand (agonist, partial agonist, and SERM antagonist) induces distinctive orientations in the receptor's carboxy-terminal transactivation helix. The conformation of this portion of the receptor determines whether ER can recruit and interact with the components of the transcriptional machinery, thereby facilitating target gene expression.

RESULTS

We have determined the structure of rat ERbeta ligand binding domain (LBD) in complex with the pure antiestrogen ICI 164,384 at 2.3 A resolution. The binding of this compound to the receptor completely abolishes the association between the transactivation helix (H12) and the rest of the LBD. The structure reveals that the terminal portion of ICI's bulky side chain substituent protrudes from the hormone binding pocket, binds along the coactivator recruitment site, and physically prevents H12 from adopting either its characteristic agonist or AF2 antagonist orientation.

CONCLUSIONS

The binding mode adopted by the pure antiestrogen is similar to that seen for other ER antagonists. However, the size and resultant positioning of the ligand's side chain substituent produces a receptor conformation that is distinct from that adopted in the presence of other classes of ER ligands. The novel observation that binding of ICI results in the complete destabilization of H12 provides some indications as to a possible mechanism for pure receptor antagonism.

Understanding the mechanism of ice binding by type III antifreeze proteins

Type III antifreeze proteins (AFPs) are present in the body fluids of some polar fishes where they inhibit ice growth at subzero temperatures. Previous studies of the structure of type III AFP by NMR and X-ray identified a remarkably flat surface on the protein containing amino acids that were demonstrated to be important for interaction with ice by mutational studies. It was proposed that this protein surface binds onto the (1 0 [\bar 1] 0) plane of ice with the key amino acids interacting directly with the water molecules in the ice crystal. Here, we show that the mechanism of type III AFP interaction with ice crystals is more complex than that proposed previously. We report a high-resolution X-ray structure of type III AFP refined at 1.15 A resolution with individual anisotropic temperature factors. We report the results of ice-etching experiments that show a broad surface coverage, suggesting that type III AFP binds to a set of planes that are parallel with or inclined at a small angle to the crystallographic c-axis of the ice crystal. Our modelling studies, performed with the refined structure, confirm that type III AFP can make energetically favourable interactions with several ice surfaces.

Experimental and computational mapping of the binding surface of a crystalline protein

Multiple Solvent Crystal Structures (MSCS) is a crystallographic technique to identify energetically favorable positions and orientations of small organic molecules on the surface of proteins. We determined the high-resolution crystal structures of thermolysin (TLN), generated from crystals soaked in 50--70% acetone, 50--80% acetonitrile and 50 mM phenol. The structures of the protein in the aqueous-organic mixtures are essentially the same as the native enzyme and a number of solvent interaction sites were identified. The distribution of probe molecules shows clusters in the main specificity pocket of the active site and a buried subsite. Within the active site, we compared the experimentally determined solvent positions with predictions from two computational functional group mapping techniques, GRID and Multiple Copy Simultaneous Search (MCSS). The experimentally determined small molecule positions are consistent with the structures of known protein--ligand complexes of TLN.

A structural biologist's view of the oestrogen receptor

Here we review the results that have emerged from our structural studies on the oestrogen receptor ligand-binding domain (ER-LBD). The effects of agonists and antagonists on the structure of ERalpha- and ERbeta-LBDs are examined. In addition, the findings from structural studies of ER-LBD in complex with peptide fragments corresponding to the NR-box II and III modules of the p160 coactivator TIF2 are discussed in the context of the assembly of ER:coactivator complexes. Together these studies have broadened our understanding of ER function by providing a unique insight into ER's ligand specificity, it's ability to interact with coactivators and the structural changes that underlie receptor agonism and antagonism.

Structural insights into the mechanisms of agonism and antagonism in oestrogen receptor isoforms

Here we summarise the results that have emerged from our structural studies on the oestrogen receptor (ER) ligand-binding domain. We have investigated the conformational effects of a variety of ligands on the structures of both ER isoforms. Each class of ligand (agonists, partial agonists and selective oestrogen receptor modulators) induces a unique conformation in the receptor's ligand-dependent transcriptional activation function. Together these studies have broadened our understanding of ER function by providing a unique insight into ER's ligand specificity and the structural changes that underlie receptor agonism and antagonism.

Structure of Fab hGR-2 F6, a competitive antagonist of the glucagon receptor

The monoclonal antibody hGR-2 F6 has been raised against the human glucagon receptor and shown to act as a competitive antagonist. As a first step in the structural characterization of the receptor, the crystal structure of the Fab fragment from this antibody is reported at 2.1 A resolution. The hGR-2 F6 Fab crystallizes in the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 76.14, b = 133.74, c = 37.46 A. A model generated by homology modelling was used as an aid in the chain-tracing and the Fab fragment structure was subsequently refined (final R factor = 21.7%). The structure obtained exhibits the typical immunoglobulin fold. Complementarity-determining regions (CDRs) L1, L2, L3, H1 and H2 could be superposed onto standard canonical CDR loops. The H3 loop could be classified according to recently published rules regarding loop length, sequence and conformation. This loop is 14 residues long, with an approximate beta-hairpin geometry, which is distorted somewhat by the presence of two trans proline residues at the beginning of the loop. It is expected that this H3 loop will facilitate the design of synthetic probes for the glucagon receptor that may be used to investigate receptor activity.

Locating interaction sites on proteins: the crystal structure of thermolysin soaked in 2% to 100% isopropanol

Multiple-solvent crystal structure determination (MSCS) allows the position and orientation of bound solvent fragments to be identified by determining the structure of protein crystals soaked in organic solvents. We have extended this technique by the determination of high-resolution crystal structures of thermolysin (TLN), generated from crystals soaked in 2% to 100% isopropanol. The procedure causes only minor changes to the conformation of the protein, and an increasing number of isopropanol interaction sites could be identified as the solvent concentration is increased. Isopropanol occupies all four of the main subsites in the active site, although this was only observed at very high concentrations of isopropanol for three of the four subsites. Analysis of the isopropanol positions shows little correlation with interaction energy computed using a molecular mechanics force field, but the experimentally determined positions of isopropanol are consistent with the structures of known protein-ligand complexes of TLN.

Glycosaminoglycans interact selectively with chemokines and modulate receptor binding and cellular responses

Chemokines selectively recruit and activate a variety of cells during inflammation. Interactions between cell surface glycosaminoglycans (GAGs) and chemokines drive the formation of haptotactic or immobilized gradients of chemokines at the site of inflammation, directing this recruitment. Chemokines bind to glycosaminoglycans on human umbilical vein endothelial cells (HUVECs) with affinities in the micromolar range: RANTES > MCP-1 > IL-8 > MIP-1alpha. This binding can be competed with by soluble glycosaminoglycans: heparin, heparin sulfate, chondroitin sulfate, and dermatan sulfate. RANTES binding showed the widest discrimination between glycosaminoglycans (700-fold), whereas MIP-1alpha was the least selective. Almost identical results were obtained in an assay using heparin sulfate beads as the source of immobilized glycosaminoglycan. The binding of chemokines to glycosaminoglycan fragments has a strong length dependence, and optimally requires both N- and O-sulfation. Isothermal titration calorimetry data confirm these results; IL-8 binds heparin fragments with a K(d) of 0.39-2.63 microM, and requires five saccharide units to bind each monomer of chemokine. In membranes from cells expressing the G-protein-coupled chemokine receptors CXCR1, CXCR2, and CCR1, soluble GAGs inhibit the binding of chemokine ligands to their receptors. Consistent with this, heparin and heparin sulfate could inhibit IL-8-induced neutrophil calcium flux. Chemokines can therefore form complexes with both cell surface and soluble GAGs; these interactions have different functions. Soluble GAG chemokines complexes are unable to bind the receptor, resulting in a block of the biological activity. Previously, we have shown that cell surface GAGs present chemokines to the G-protein-coupled receptors, by increasing the local concentration of protein. A model is presented which brings together all of these data. The selectivity in the chemokine-GAG interaction suggests selective disruption of the haptotactic gradient may be an achievable therapeutic approach in inflammatory disease.

Structure of the ligand-binding domain of oestrogen receptor beta in the presence of a partial agonist and a full antagonist

Oestrogens exert their physiological effects through two receptor subtypes. Here we report the three-dimensional structure of the oestrogen receptor beta isoform (ERbeta) ligand-binding domain (LBD) in the presence of the phyto-oestrogen genistein and the antagonist raloxifene. The overall structure of ERbeta-LBD is very similar to that previously reported for ERalpha. Each ligand interacts with a unique set of residues within the hormone-binding cavity and induces a distinct orientation in the AF-2 helix (H12). The bulky side chain of raloxifene protrudes from the cavity and physically prevents the alignment of H12 over the bound ligand. In contrast, genistein is completely buried within the hydrophobic core of the protein and binds in a manner similar to that observed for ER's endogenous hormone, 17beta-oestradiol. However, in the ERbeta-genistein complex, H12 does not adopt the distinctive 'agonist' position but, instead, lies in a similar orientation to that induced by ER antagonists. Such a sub-optimal alignment of the transactivation helix is consistent with genistein's partial agonist character in ERbeta and demonstrates how ER's transcriptional response to certain bound ligands is attenuated.

Relating structure to thermodynamics: the crystal structures and binding affinity of eight OppA-peptide complexes

The oligopeptide-binding protein OppA provides a useful model system for studying the physical chemistry underlying noncovalent interactions since it binds a variety of readily synthesized ligands. We have studied the binding of eight closely related tripeptides of the type Lysine-X-Lysine, where X is an abnormal amino acid, by isothermal titration calorimetry (ITC) and X-ray crystallography. The tripeptides fall into three series of ligands, which have been designed to examine the effects of small changes to the central side chain. Three ligands have a primary amine as the second side chain, two have a straight alkane chain, and three have ring systems. The results have revealed a definite preference for the binding of hydrophobic residues over the positively charged side chains, the latter binding only weakly due to unfavorable enthalpic effects. Within the series of positively charged groups, a point of lowest affinity has been identified and this is proposed to arise from unfavorable electrostatic interactions in the pocket, including the disruption of a key salt bridge. Marked entropy-enthalpy compensation is found across the series, and some of the difficulties in designing tightly binding ligands have been highlighted.

Structure of the protein tyrosine kinase domain of C-terminal Src kinase (CSK) in complex with staurosporine

The crystal structure of the kinase domain of C-terminal Src kinase (CSK) has been determined by molecular replacement, co-complexed with the protein kinase inhibitor staurosporine (crystals belong to the space group P21212 with a=44.5 A, b=120.6 A, c=48.3 A). The final model of CSK has been refined to an R-factor of 19.9 % (Rfree=28.7 %) at 2.4 A resolution. The structure consists of a small, N-terminal lobe made up mostly of a beta-sheet, and a larger C-terminal lobe made up mostly of alpha-helices. The structure reveals atomic details of interactions with staurosporine, which binds in a deep cleft between the lobes. The polypeptide chain fold of CSK is most similar to c-Src, Hck and fibroblast growth factor receptor 1 kinase (FGFR1K) and most dissimilar to insulin receptor kinase (IRK). Interactions between the N and C-terminal lobe are mediated by the bound staurosporine molecule and by hydrogen bonds. In addition, there are several water molecules forming lobe-bridging hydrogen bonds, which may be important for maintaining the catalytic integrity of the kinase. Furthermore, the conserved Lys328 and Glu267 residues utilise water in the formation of a molecular pivot which is essential in allowing relative movement of the N and C-terminal lobes. An analysis of the residues around the ATP-binding site reveals structural differences with other protein tyrosine kinases. Most notable of these are different orientations of the conserved residues Asp332 and Phe333, suggesting that inhibitor binding proceeds via an induced fit. These structural observations have implications for understanding protein tyrosine kinase catalytic mechanisms and for the design of ATP-mimicking inhibitors of protein kinases.

The design, synthesis, and evaluation of novel conformationally rigid analogues of sialyl Lewis(x)

The design and synthesis of a series of analogues of sialyl Lewis(x)(1) which incorporate conformationally rigid tetralin and naphthalene ring systems(2-4) has led to novel compounds which have similar potency to 1 as inhibitors of cell adhesion.

Ligand-induced conformational change in penicillin acylase

The enzyme penicillin acylase (penicillin amidohydrolase EC 3.5.1. 11) catalyses the cleavage of the amide bond in the benzylpenicillin (penicillin G) side-chain to produce phenylacetic acid and 6-aminopenicillanic acid (6-APA). The enzyme is of great pharmaceutical importance, as the product 6-APA is the starting point for the synthesis of many semi-synthetic penicillin antibiotics. Studies have shown that the enzyme is specific for hydrolysis of phenylacetamide derivatives, but is more tolerant of features in the rest of the substrate. It is this property that has led to many other applications for the enzyme, and greater knowledge of the enzyme's structure and specificity could facilitate engineering of the enzyme, enhancing its potential for chemical and industrial applications. An extensive study of the binding of a series of phenylacetic acid derivatives has been carried out. A measure of the relative degree of inhibition of the enzyme by each of the compounds has been obtained using a competitive inhibition assay, and the structures of a number of these complexes have been determined by X-ray crystallography. The structures reveal a clear rationale for the observed kinetic results, but show also that some of the ligands cause a conformational change within the binding pocket. This change can generally be understood in terms of the size and orientation of the ligand within the active site.The results reveal that ligand binding in penicillin acylase is facilitated by certain amino acid residues that can adopt two distinct, energetically favourable positions in order to accommodate a variety of compounds within the active site. The structures of these complexes provide evidence for conformational changes in the substrate-binding region that may act as a switch in the mechanism of autocatalytic processing of this enzyme.

Combined biophysical and biochemical information confirms arrangement of transmembrane helices visible from the three-dimensional map of frog rhodopsin

The electron density projection map of frog rhodopsin at 6 A resolution had been until recently the most direct evidence for the three-dimensional structure of a transmembrane domain of any G-protein-coupled receptor. Only three out of seven transmembrane helices are clearly defined, whilst the other four are hidden in a patch of unresolved electron density. A model of the seven-helix bundle has been created by generating positions and orientations for the four unresolved helices through performing a conformational search directed by structural restraints derived from other experimental data. These four helices are significantly tilted with respect to the membrane normal, and the cytosolic end of helix C is inserted between helices D and E. These calculations produce positions and orientations for these additional helices that are consistent with the recently published low-resolution three-dimensional map, and provide a template for more detailed modelling of rhodopsin structure and function.