A Prospective Pilot Study to Measure Changes in Functional Status Associated With Hospitalization in Elderly Dialysis-Dependent Patients

Narrative Review: Clinical Implications and Assessment of Frailty in Patients With Advanced CKD

Frailty is a multidimensional clinical syndrome characterized by low physical activity, reduced strength, accumulation of multiorgan deficits, decreased physiological reserve, and vulnerability to stressors. Frailty has key social, psychological, and cognitive implications. Frailty is accelerated by uremia, leading to a high prevalence of frailty in patients with advanced chronic kidney disease (CKD) and end-stage kidney disease (ESKD) as well as contributing to adverse outcomes in this patient population. Frailty assessment is not routine in patients with CKD; however, a number of validated clinical assessment tools can assist in prognostication. Frailty assessment in nephrology populations supports shared decision-making and advanced communication and should inform key medical transitions. Frailty screening and interventions in CKD or ESKD are a developing research priority with a rapidly expanding literature base.

Use of frailty assessment instruments in nephrology populations: a scoping review

BACKGROUND

Frailty is a clinical syndrome of accelerated aging associated with adverse outcomes. Frailty is prevalent among patients with chronic kidney disease but is infrequently assessed in clinical settings, due to lack of consensus regarding frailty definitions and diagnostic tools. This study aimed to review the practice of frailty assessment in nephrology populations and evaluate the context and timing of frailty assessment.

METHODS

The search included published reports of frailty assessment in patients with chronic kidney disease, undergoing dialysis or in receipt of a kidney transplant, published between January 2000 and November 2021. Medline, CINAHL, Embase, PsychINFO, PubMed and Cochrane Library databases were examined. A total of 164 articles were included for review.

RESULTS

We found that studies were most frequently set within developed nations. Overall, 161 studies were frailty assessments conducted as part of an observational study design, and 3 within an interventional study. Studies favoured assessment of participants with chronic kidney disease (CKD) and transplant candidates. A total of 40 different frailty metrics were used. The most frequently utilised tool was the Fried frailty phenotype. Frailty prevalence varied across populations and research settings from 2.8% among participants with CKD to 82% among patients undergoing haemodialysis. Studies of frailty in conservatively managed populations were infrequent (N = 4). We verified that frailty predicts higher rates of adverse patient outcomes. There is sufficient literature to justify future meta-analyses.

CONCLUSIONS

There is increasing recognition of frailty in nephrology populations and the value of assessment in informing prognostication and decision-making during transitions in care. The Fried frailty phenotype is the most frequently utilised assessment, reflecting the feasibility of incorporating objective measures of frailty and vulnerability into nephrology clinical assessment. Further research examining frailty in low and middle income countries as well as first nations people is required. Future work should focus on interventional strategies exploring frailty rehabilitation.

Self-reported Physical Function Decline and Mortality in Older Adults Receiving Hemodialysis

Rationale & Objective

Timely recognition of functional decline in older adults receiving dialysis will allow clinicians to pursue interventions to prevent further disability and/or lead patient-centered goals of care discussions. Annual change in the 12-Item Short Form Health Survey (SF-12) physical component score (PCS) could identify patients with functional decline. Our objectives were to assess SF-12 PCS change over a year, risk factors associated with SF-12 PCS change, and the association of SF-12 PCS change with mortality in a survivor cohort of older adults receiving dialysis.

Study Design

Retrospective study.

Setting & Participants

1,371 adults 65 years or older receiving hemodialysis for 6 or more months who completed SF-12 PCSs 300 or more days apart from 2012 to 2013.

Exposures

Serum albumin level; hemodialysis access type; SF-12 PCS change (for mortality analyses).

Outcomes

SF-12 PCS change and mortality.

Analytical Approach

Multivariable-adjusted linear regression model; Cox proportional hazards model.

Results

We excluded 24% (n = 801) of our cohort for death before the second SF-12 PCS. Among the 1,371 with sufficient SF-12 PCS data, mean age was 79.9 ± 4.5 years. Average SF-12 PCS change in 1 year was minimal (−0.9 ± 9.6), but 39.3% (n = 539) and 32.2% (n = 442) had clinically relevant SF-12 PCS decline and improvement, respectively. Albumin level and access type were not statistically associated with SF-12 PCS change. SF-12 PCS change was not associated with mortality (adjusted HR, 0.98; 95% CI, 0.96-1.00).

Limitations

2 time points to assess SF-12 PCS change; covariate assessment only at baseline; survivor bias.

Conclusions

In this cohort of older adults receiving hemodialysis, nearly one-fourth died, while among survivors, it was more common for SF-12 PCS to decline than improve in a year. Annual SF-12 PCS change was not associated with traditional risk factors for functional impairment or mortality risk. Additional research is needed to identify appropriate measures and frequency of assessment for functional decline.

Hemodialysis vascular access in the elderly-getting it right

Choosing the optimal hemodialysis vascular access for the elderly patient is best achieved by a patient-centered coordinated multidisciplinary team approach that aligns the patient's end-stage kidney disease Life-Plan, i.e., the individual treatment approach (supportive care, time-limited or long-term kidney replacement therapy, or combination thereof) and selection of dialysis modality (peritoneal dialysis versus hemodialysis) with the most suitable dialysis access. Finding the right balance between the patient's preferences, the likelihood of access function and survival, and potential complications in the context of available resources and limited patient survival can be extremely challenging. The framework for choosing the most appropriate vascular access for the elderly presented in this review considers the individual end-stage kidney disease Life-Plan, the patient life expectancy, the likelihood of access function and survival, the timing of dialysis relative to access placement, prior access history, and patient preference. This complex decision-making process should be dynamic in order to accommodate patients' changing needs and life and health circumstances. Effective and timely communication between the patient, their caregivers, and treating team is key to delivering truly patient-centered care. Delivering this care also requires overcoming the limitations of the currently available evidence that is predominantly based on observational data with its inherent risks of bias. While challenging, future randomized controlled studies exploring the risks, benefits, costs, and timing of placement of available access types in the elderly are required to help us "get it right" for our patients.

PD Assistance and Relationship to Co-Existing Geriatric Syndromes in Incident Peritoneal Dialysis Therapy Patients

Background:Home dialysis therapies, including peritoneal dialysis (PD), are preferred treatment strategies, offering flexibility and improved wellbeing. However, patients with complex disease and comorbidity may require assistance with personal care and healthcare-related tasks. The study objective was to formally assess the type and frequency of PD assistance received by patients over 50, and the relationship to observed frailty, functional status, and cognitive ability at the time of PD therapy initiation.Methods:Using a multicentered, prospective observational study design, patients aged ≥ 50 years were recruited from those starting PD. Patients underwent formal evaluation using validated components of a Comprehensive Geriatric Assessment. The receipt and nature of assistance with PD tasks were assessed 1 month after dialysis start by questionnaire.Results:A total of 121 patients (age 69 ± 10 years, 67% male, 54% diabetic) were recruited. A total of 75 (62%) patients received assistance for a variety of tasks from friends or family (n = 41, 34%) or a paid caregiver (n = 34, 28%) 1 month after starting dialysis. At baseline, there was a high prevalence of functional dependency (79/120, 66%), frailty (71/110, 65%), and impaired cognition (68/115, 59%). Only 5% were fully independent, clinically robust, and scored within the normal range on cognitive testing. Factors associated with PD assistance included comorbidity (p < 0.03), cognitive impairment (p < 0.0001), and functional dependence (p < 0.02).Conclusion:Older patients initiating PD in the outpatient setting have high rates of frailty, functional dependence, and cognitive changes at the time they initiate dialysis. More research is required to better understand how those factors contribute to the use of PD assistance.

Functional Status in Hemodialysis - A Comparative Study with FIM, ADLQ and 7D5L Instruments

There is only limited information on the functional status (FS) of patients receiving hemodialysis (HD) from developing countries where the etiology of chronic kidney disease (CKD) and demographic profile are different. The study aims to assess the FS in patients with CKD using three validated generic instruments. A total of 116 adult patients on HD with a dialysis vintage >3 months were enrolled. FS was assessed using three generic tools – Functional Independence Measure (FIM) (scores 18–126), Seven domains and five levels (7D5L) (scores 0–28), and Activities of Daily Living Questionnaire (ADLQ) (scores 0–6) scales. A higher FIM and ADLQ scores and lower 7D5L score indicated good FS. The mean age of patients was 41.28 ± 15.44 years. About 77.6% were males and 80.2% were unemployed. About 67.2% were receiving twice-weekly HD, and 28.4% were receiving thrice-weekly dialysis. The mean scores were 119.05 ± 11.42 with FIM, 6.44 ± 4.26 with 7D5L, and 5.51 ± 1.19 with ADL instruments. More than 80% showed full functional independence with ADLQ instrument. With FIM, the overall scores showed a tendency for functional independence, but the subdomains involving locomotion/mobility were impaired to a greater extent. The proportion of patients with full independence was less with 7D5L. We observed an inferior FS in individuals <40 years. Patients on HD were functionally independent as assessed by FIM and ADLQ instruments. However, 7D5L appeared to be better in identifying mild to moderate limitations in daily activities. The domains involving motor tasks seem to be affected to a greater extent. The current scales for assessing FS do not incorporate a time-dependent component.

Factors Associated with Frailty and Its Trajectory among Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

Frailty is common among patients on hemodialysis and associated with adverse outcomes. However, little is known about changes in frailty over time and the factors associated with those changes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

To address these questions, we examined 762 participants in the A Cohort to Investigate the Value of Exercise/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESRD cohort study, among whom frailty was assessed at baseline and 12 and 24 months. We used ordinal generalized estimating equations analyses and modeled frailty (on a scale from zero to five possible components) and death during follow-up.

RESULTS

The mean frailty score at baseline was 1.9, and the distribution of frailty scores was similar at each evaluation. However, most participants' scores changed, with patients improving almost as often as worsening (overall change, 0.2 points per year; 95% confidence interval, 0.1 to 0.3). Hispanic ethnicity (0.6 points per year; 95% confidence interval, 0.0 to 1.1) and diabetes (0.7 points per year; 95% confidence interval, 0.3 to 1.0) were associated with higher frailty scores and higher serum albumin concentration with lower frailty scores (-1.1 points per g/dl; 95% confidence interval, -1.5 to -0.7). In addition, patients whose serum albumin increased over time were less likely to become frail, with each 1-g/dl increase in albumin associated with a 0.4-point reduction in frailty score (95% confidence interval, -0.80 to -0.05). To examine the underpinnings of the association between serum albumin and frailty, we included serum IL-6, normalized protein catabolic rate, and patient self-report of hospitalization within the last year in a second model. Higher IL-6 and hospitalization were statistically significantly associated with worse frailty at any point and worsening frailty over time, whereas normalized protein catabolic rate was not independently associated with frailty.

CONCLUSIONS

There was substantial year to year variability in frailty scores, with approximately equal numbers of patients improving and worsening. Markers of inflammation and hospitalization were independently associated with worsening frailty. Studies should examine whether interventions to address inflammation or posthospitalization rehabilitation can improve the trajectory of frailty.

Morbidity, mortality and quality of life in the ageing haemodialysis population: results from the ELDERLY study

Background

The physical–functional and social–emotional health as well as survival of the elderly (≥75 years of age) haemodialysis patient is commonly thought to be poor. In a prospective, multicentre, non-interventional, observational study, the morbidity, mortality and quality of life (QoL) in this patient group were examined and compared with a younger cohort.

Methods

In 92 German dialysis centres, 2507 prevalent patients 19–98 years of age on haemodialysis for a median of 19.2 months were included in a drug monitoring study of darbepoetin alfa. To examine outcome and QoL parameters, 24 months of follow-up data in the age cohorts <75 and ≥75 years were analysed. Treatment parameters, adverse and intercurrent events, hospitalizations, morbidity and mortality were assessed. QoL was evaluated by means of the 47-item Functional Assessment of Chronic Illness Therapy–Anaemia score (FACT-An, version 4).

Results

The 2-year mortality rate was 34.7% for the older cohort and 15.8% for the younger cohort. The mortality rate for the haemodialysed elderly patients was 6.2% higher in absolute value compared with the age-matched background population. A powerful predictor of survival was the baseline FACT-An score and a close correlation with the 20-item anaemia subscale (AnS) was demonstrated. While the social QoL in the elderly patients was more stable than in the younger cohort (leading to equivalent values at the end of the study period), a pronounced deterioration of physical and functional status was observed. The median number of all-cause hospital days per patient-year was 12.3 for the elderly cohort and 8.9 for the younger patient population. The overall 24-month hospitalization rate was only marginally higher in the elderly cohort (34.0 versus 33.3%).

Conclusions

In this observational study, the mortality rate of elderly haemodialysis patients was not exceedingly high compared with the age-matched background population. Furthermore, the hospitalization rate was only slightly higher compared with the younger age group and the median yearly hospitalization time trended lower compared with registry data. The social well-being of elderly haemodialysis patients showed a less pronounced decline over time and was equal to the score of the younger cohort at the end of the study period. The physical and functional status in the elderly patients was lower and showed a sharper decline over time. The baseline FACT-An score correlated closely with the 24-month survival probability.

End-stage renal disease in the elderly: dialysis or conservative management?

The challenges of health care in an aging population are mirrored in the field of nephrology, in which an increasing proportion of the population has chronic kidney disease (CKD) and end-stage renal disease requiring dialysis. The need for dialysis negatively influences survival and health-related quality of life (HRQoL) in all age groups, but particularly in the elderly, raising the issue of withholding dialysis and emphasizing conservative management of CKD in some patients. Increased mortality is seen in dialysis patients who are elderly, have significant comorbidities, and have poor functional status. In such patients, the option of palliative care should be discussed in order to focus on HRQoL in the physical, psychological, and social domains. Although survival among the elderly who forgo dialysis is worse than those who begin dialysis, hospitalizations and HRQoL may be better, especially if the CKD-associated complications are appropriately addressed through effective palliative care.

End-Stage Kidney Disease in the Elderly: Approach to Dialysis Initiation, Choosing Modality, and Predicting Outcomes

The number of patients with end-stage kidney disease 65 years and older is growing, and this growth is expected to continue. The presence of medical comorbidities, limited life expectancy, frailty, and poor functional status in these patients poses substantial challenges in clinical decision-making and provision of optimal care. Frailty is more common in elderly patients with CKD than without and is associated with poor outcomes. Several prognostic tools were developed to estimate the rate of CKD progression among elderly, and risk of mortality after dialysis initiation. Risk factors for CKD progression among elderly include low estimated glomerular filtration rate, high baseline proteinuria, acute kidney injury, low serum albumin, and presence of congestive heart failure. The decision to initiate dialysis in the elderly should take into consideration life expectancy, risks and benefits of each dialysis modality, quality of life, and patient and caregiver preferences. This article discusses common issues in the elderly with end-stage kidney disease, with particular emphasis on the impact of frailty and functional status, choice of dialysis modality and vascular access, and prognosis after dialysis initiation, to assist the nephrologist in making decisions regarding optimal care for this complex group of patients.

Functional Dependence and Mortality in the International Dialysis Outcomes and Practice Patterns Study (DOPPS)

BACKGROUND

Patients receiving long-term dialysis have among the highest mortality and hospitalization rates. In the nonrenal literature, functional dependence is recognized as a contributor to subsequent disability, recurrent hospitalization, and increased mortality. A higher burden of functional dependence with progressive worsening of kidney function has been observed in several studies, suggesting that functional dependence may contribute to both morbidity and mortality in dialysis patients.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

7,226 hemodialysis patients from 12 countries in the DOPPS (Dialysis Outcomes and Practice Patterns Study) phase 4 (2009-2011) with self-reported data for functional status.

PREDICTOR

Patients' ability to perform 13 basic and instrumental activities of daily living was summarized to create an overall functional status score (range, 1.25 [most dependent] to 13 [functionally independent]).

OUTCOME

Cox regression was used to estimate the association between functional status and all-cause mortality, adjusting for several demographic and clinical risk factors for mortality. Median follow-up was 17.2 months.

RESULTS

The proportion of patients who could perform each activity of daily living task without assistance ranged from 97% (eating) to 47% (doing housework). 36% of patients could perform all 13 tasks without assistance (functional status = 13), and 14% of patients had high functional dependence (functional status < 8). Functionally independent patients were younger and had many indicators of better health status, including higher quality of life. Compared with functionally independent patients, the adjusted HR for mortality was 2.37 (95% CI, 1.92-2.94) for patients with functional status < 8.

LIMITATIONS

Possible nonresponse bias and residual confounding.

CONCLUSIONS

We found a high burden of functional dependence across all age groups and across all DOPPS countries. When adjusting for several known mortality risk factors, including age, access type, cachexia, and multimorbidity, functional dependence was a strong consistent predictor of mortality.

Needs of Hemodialysis Patients and Factors Affecting Them

Purpose:

Of this study was to explore the needs of hemodialysis patients and the factors that affect them.

Material & Methods:

The sample of the study included 141 patients undergoing hemodialysis. Data collection was performed by the method of interview using a specially designed questionnaire which served the purposes of the study. The needs were grouped into six categories. Patients were asked to answer how important was for them each of the statements in the questionnaire. Furthermore, there were collected socio-demographic characteristics, information on health status and relations with the physicians and nurses, as well as data on the incidence of the disease in their social life.

Results:

The results of this study showed that patients evaluated as fairly important all six categories of their needs, with similar results in both sexes. Age was found to be statistically significantly associated with ’the need for support and guidance’, ’the need to be informed’ and ’the need to meet the emotional and physical needs’, (p=0.023, p=0.012, p=0.028 respectively). Education level was found to be statistically significantly associated with all patients’ needs with the exception of ’the need to trust the medical and nursing staff’, (p=<0.05). Place of residence was statistically significantly associated with ’the need for support and guidance’, (p=0.029). Furthermore, difficulties in relations with family members was found to be statistically significantly associated with ’the need for support, the need for communication and individualization of care’, (p=0.014, p=0.040, p=0.041). After multivariate analysis, however, it was shown that the only independent factor affecting ’the need for support and guidance’, ’the need for individualized care’ and ’the need to meet the emotional and physical needs’, was if the patients reported themselves as anxious or not (p=0,024, p=0,012 and p=0,004, respectively). In particular, patients who considered themselves anxious had 1.38, 1.5 and 1.6 points respectively higher score in the evaluation of the importance of needs compared to patients who did not consider themselves anxious.

Conclusions:

Factors affecting needs of hemodialysis patients are age, education level, place of residence difficulties in relations with family members as well as anxious personality as reported by the patients.

Risk of death following kidney allograft failure: a systematic review and meta-analysis of cohort studies

BACKGROUND

People with kidney allograft failure represent an increasing fraction of all those starting dialysis therapy. We sought to summarize prognosis following kidney allograft failure and identify potentially beneficial interventions or modifiable risk factors.

METHODS

We searched MEDLINE and EMBASE (inception to 1 October 2013) and article reference lists without language restriction and selected cohort studies of all-cause mortality and fatal infection-related and cardiovascular events in people starting dialysis following kidney allograft failure. Two reviewers independently extracted data on study design, participant characteristics, dialysis modality, transplant nephrectomy, immunosuppression strategy, transplant-naive comparators and risk of bias. Discrepancies were resolved with a third reviewer.

RESULTS

Forty studies comprising 249 716 participants met the inclusion criteria. The first year of dialysis therapy was associated with the highest mortality. By random effects meta-analysis, annual risk of death, from years 1 to 4, was 0.12 [95% confidence interval (95% CI): 0.09-0.15], 0.06 (95% CI: 0.05-0.07), 0.05 (95% CI: 0.04-0.06) and 0.05 (95% CI: 0.04-0.06), respectively. We found high heterogeneity in each meta-analysis, which remained unexplained by prespecified subgroup analyses. We could not find sufficient information to summarize the risk for fatal infection-related and cardiovascular events, or to test the role of transplant nephrectomy or different immunosuppressive strategies. Risk of bias was high, especially participation bias.

CONCLUSION

Mortality is higher during the first year of dialysis treatment following kidney allograft failure than in subsequent years. Insufficient data are available to assess factors or interventions potentially impacting prognosis following kidney allograft failure. In a culture promoting transplantation, clinical research of different models of care in this growing high-risk population should be a research priority.

Dialysis therapies in older patients with end-stage renal disease

Each year a large number of older individuals with advanced renal disease are started on chronic dialysis therapy. Life expectancy is estimated at between 2 and 4 years depending on age, comorbidity, and intensity of medical care required in the weeks around the dialysis start time. Survivors remain at high risk of ongoing morbidity. Regarding quality of life, many older patients express regret over having opted for chronic dialysis therapy and subsequently choose to withdraw from treatment, whereas many others maintain a quality of life similar to that of age-matched peers. Early assessment and ongoing comprehensive geriatric assessment is recommended.

Exercise program to enhance physical performance and quality of life of older hemodialysis patients: a feasibility study

OBJECTIVE

Evaluate the feasibility of implementing a combined in-hospital and home-based exercise program in older hemodialysis (HD) patients.

DESIGN

A prospective longitudinal 12-week pilot study.

SETTING

A university hospital HD unit and patients' homes.

PARTICIPANTS

A convenience sample of nine older (>55 years) patients undergoing HD.

INTERVENTIONS

An individualized exercise program performed on HD days (3/week) and at home (2-3/week), including aerobic, flexibility, strength exercises and patient education.

MAIN OUTCOME MEASURES

Feasibility measure: patient participation. Exercise performance: Duke Activity Status Index (DASI); 2-min walk test (2MWT); Timed-up-and-go (TUG). Quality of life: The Illness Intrusiveness Ratings Scale (IIRS); The Kidney Disease Quality of Life Questionnaire (KDQOL).

RESULTS

The mean (SD) age of the patients was 68.1 (7.1). Participation in the in-hospital supervised exercise program was high, with patients exercising during 89% of HD sessions, but was lower for the unsupervised home-based component (56% exercised ≥ 2 times/week). Patients showed a gradual increase in the amount of exercise performed over 12 weeks. The 2MWT, TUG, IIRS and the KDQOL physical composite score demonstrated moderate responsiveness, while the DASI score exhibited only limited responsiveness.

CONCLUSIONS

This exercise program and the outcome measures were feasible for older HD patients: in-hospital participation was high, and physical performance and QOL measures exhibited moderate levels of responsiveness. Future, larger studies are needed to demonstrate whether intra-dialysis exercise, with or without home exercise, can lead to improved outcomes in this population.

Clinical presentation of renal failure in the aged: chronic renal failure

Chronic kidney disease is increasingly being recognized in elderly individuals across the world. An understanding of the methods used to estimate or to measure kidney function, the likelihood and factors associated with progressive decline in renal function, and the clinical syndromes associated with poor renal function are key topics for individuals working across many medical disciplines. This review addresses some of the important aspects of chronic kidney disease, and summarizes some of the clinical and laboratory features associated with progressive disease.

The intersection of geriatrics and chronic kidney disease: frailty and disability among older adults with kidney disease

Older adults (aged >or=65 years) comprise the largest segment of the CKD population, and impaired kidney function is linked with unsuccessful aging. Individuals across the spectrum of kidney disease have clinical features of the frailty phenotype, suggesting that frailty is not confined to old age among vulnerable populations. This manifests as a high prevalence of impaired physical performance, emergent geriatric syndromes, disability, and risk of death. Considering the multiple system involvement underlying the symptoms and deficits seen in CKD, especially in the more severe stages, the concept of frailty is a highly useful tool to identify older adults with kidney disease who are on the trajectory of vulnerability leading to decline and death. Further work is needed to characterize the relationship between kidney disease and frailty and to identify opportunities to intervene.

Physical function in older candidates for renal transplantation: an impaired population

BACKGROUND AND OBJECTIVES

Although physical function is a major determinant of health outcomes and quality of life in older adults, standard tools for its assessment have not been routinely applied to the fastest growing segment of the kidney transplant candidate population, which is at high risk of comorbidity and disability--people over age 60. The objective of this study was to describe the baseline physical function in older adults with renal failure referred for transplantation and compare them with older adults with other significant comorbidity.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

An observational sample comparing physical performance in renal transplant candidates over age 60 (Renal Failure) to older people with diastolic heart failure (Heart Failure), chronic obstructive pulmonary disease (COPD), or at high risk for cardiovascular disease (High CV Risk) was studied.

RESULTS

Older people with Renal Failure were significantly impaired by objective measures of physical function, including lower Short Physical Performance Battery, slower gait speed, and lower grip strength.

CONCLUSIONS

Older people referred for renal transplantation had poorer physical performance than older adults with other common chronic diseases and may be at high risk for disability while awaiting transplantation.