State of the Science for Cardiovascular Nursing Outcomes: Heart Failure

The incidence of heart failure is increasing because of the progressive aging of the population and improved survival from cardiovascular disease. This article synthesizes the state of the science of nurse sensitive outcomes in heart failure treated medically or surgically and provides recommendations for building the science. Outcomes studied include mortality, morbidity, resource use, quality of life, symptoms, physical function, return to work, and self-care and compliance behavior. Gaps in the literature are identified and recommendations for future research are provided.

Heart failure (HF) is increasing in incidence with an aging population and improved survival from cardiovascular disease. Mortality, morbidity, healthcare resource use, and costs after diagnosis remain high despite new therapies.¹ Patients often have significant limitations in multiple areas including physical, cognitive, emotional, and social functioning, and health-related quality of life (HRQoL), as well as symptom management. Knowledge of the effect of HF and its treatment on these important outcomes provides guidance for the development of interventions to improve these outcomes. Many of these interventions are nurse sensitive (ie, partially or wholly influenced by nursing care). Nurses and other providers are accountable for identifying outcomes influenced by HF and its treatment and contributing strategies to improve outcomes.

The purposes of this article were to: (1) identify and describe recent research that focuses on nurse sensitive outcomes of patients with HF, (2) identify gaps in the literature, and (3) provide recommendations for future research. A search for appropriate articles was undertaken, as described in the Foreword, for the interval 1990 to present, with additional searches of article references and scans of HF journals. Searches were conducted using the keywords heart failure, heart transplantation (HT), ventricular assist device (VAD) and cross-referenced with specific outcomes such as healthcare costs, psychosocial function, etc. Titles, authors, and abstracts were reviewed to determine if they met the criteria of nurses as authors and/or focus on patient outcomes that were nurse sensitive. We made no attempt to prioritize outcomes; rather we chose to examine many diverse outcomes that are affected by HF and its associated therapies.

Limitations of our approach must be acknowledged. First, this overview is not exhaustive but does represent most of the studies conducted related to outcomes of patients with HF. Another limitation is that several studies reported on more than one outcome. Thus, the outcomes from these studies may be described in more than one location in the text.

For organizational purposes, the article is divided into research with HF patients treated medically and those treated surgically. Outcomes for patients treated surgically include only those patients with advanced HF whose surgical therapy is considered to be life saving (ie, implantation of a (VAD and/or HT). Many other surgical therapies (eg, coronary artery bypass grafting) and cardiovascular procedures (eg, percutaneous coronary interventions) may be used to complement HF medical therapy. However, a discussion of outcomes after these procedures is beyond the scope of this article.

Outcomes of Medically Treated HF Patients

Cost and Resource Use

Although cost and healthcare resource use have not traditionally been considered nurse sensitive outcomes, nursing research has demonstrated that nursing interventions can affect these outcomes. Six studies of factors predicting readmission for HF patient were located.^2-7 The studies evaluated different factors using different methodologies and HF samples and only 2 controlled for other variables that affect hospitalization. Although no consensus on findings can be claimed, these 6 studies provide insight into the multifactoral contribution of physical, psychosocial, and system variables to readmissions for HF patients. Further research is needed to determine interactions among variables and the relative importance of various factors that may be amenable to intervention.

The need to address multiple, complex factors contributing to hospitalizations due to HF has led to the development and testing of HF programs of care to reduce healthcare costs and improve outcomes. Nurse researchers (and others) have provided strong evidence for the efficacy of such programs in decreasing healthcare resource use, cost, and mortality.^8-18 The strength of these studies is their demonstration in randomized clinical trials (sample sizes ranged from 97 to 363 patients) of the importance of multidisciplinary programs, with an emphasis on interventions by nurses. Most studies showed positive effects with reductions in readmission (HF and all cause) and death (range; 28%-62%). Although the studies have typically examined short-term outcomes (3-6 months), Stewart¹⁷ has demonstrated long-term positive effects of a home-based intervention on hospitalization of patients with HF, healthcare costs, and mortality persisting up to 4 years.

Most, but not all, of the randomized trials have included enhanced discharge planning, at least 1 home visit, optimal medical management, patient education, assessment of patient and home environment (early after discharge), and coordination of care. Further research is needed to define essential elements of programs, risk stratify patients, determine HF patients most likely to benefit, match intervention dose and nursing skill mix to patient need, and evaluate the effect of these programs on psychosocial and functional outcomes. Although not solely focused on HF patients, evaluations of the Quality Cost Model of Advanced Practice Nursing (APN) Transitional Care has begun to provide important answers related to types of patient problems, APN interventions, and intervention dose effects.^19,20 The predominant APN function in the model was found to be surveillance, with focused health teaching and early detection of problems explaining the reduction in hospitalizations and healthcare costs.²⁰ This is similar to Stewart's observation that one of the primary benefits of a home-based intervention was the detection of early clinical deterioration in high-risk HF patients.²¹

Symptoms, Symptom Management, and Self-care

Symptoms and symptom management by HF patients have been studied by nurse researchers. Three studies (2 retrospective record reviews and 1 interview study of 57 HF patients) evaluated symptoms leading to the decision to seek care. All 3 studies identified dyspnea as the most common symptom, experienced by a majority of patients (76%-91%), lasting for a mean duration of 3 days prior to seeking treatment.^22-24 A retrospective review of 753 admissions found that dyspnea, edema, care by a primary care physician, and higher NYHA class increased delay time before seeking care, while chest pain and previous admission for HF decreased delay time.²⁴ Interviews with HF patients indicated that the intensity and distress of dyspnea, not its duration, were associated with the decision to seek treatment.²³

A few studies evaluated symptoms and ability to monitor and manage symptoms in patients' daily lives. Focus groups (23 HF patients and 18 family members) were used to assess HF symptoms' experience and strategies for managing symptoms.²⁵ The most common symptoms reported were dyspnea, diuretic-related symptoms, edema, cognitive problems, loss of balance, chest pain, tiredness, and difficulty sleeping, and emotional symptoms of fear, depression, and sadness. Strategies used for management were varied and encompassed physical, psychological, and treatment-related activites.²⁵ The common problem of fatigue was evaluated in a sample of 66 women and 92 men with HF, who reported similar levels and descriptions of fatigue.²⁶ Symptom monitoring and management, fluid intake monitoring, and daily weights were infrequently performed self-care behaviors in a study of 110 HF patients (mean age-64, 22% women, 63% African American).²⁷ Monitoring and managing symptoms were affected by age, race, living alone, health state, and level of shortness of breath.²⁷ In a study of 209 HF patients, education and symptom severity were predictors of a person's ability to identify important signs and symptoms of HF.²⁸ Despite adequate sample sizes, these studies have only begun to focus our attention on symptoms experienced by HF patients and factors affecting symptom monitoring and management. The latter 2 studies provided clear conceptual frameworks for defining and measuring self-care, and could serve as models for future studies.^27,28

Factors that affect compliance have been identified as patient beliefs, attitudes, experience of HF, social support, social activities, relationships with healthcare professionals, higher education, higher mental and physical health status, and neuroticism.^3,29,30 As with symptoms, these studies are exploratory and provide no consensus except to again illustrate the multifactoral nature of behavior. Strong evidence from nursing studies supports the relationship between compliance and HF decompensation and readmission.^3,4,5

A nursing education and support intervention was effective in improving self-care behaviors 1 and 3 months after discharge in HF patients, but patients in both groups (N = 128) described limitations in knowledge, judgement/decision making, and skills.³¹ A pilot-study of a Web-based home care monitoring system in a small sample of HF patients (N = 18) showed favorable results in improving compliance with medications, and blood pressure and daily weight monitoring as compared to usual care³²; HRQoL also improved in the intervention group.³² Both of these randomized trials showed promising results, with the need for further study with larger samples.

Health-related Quality of Life

Heart failure patients' HRQoL and their experiences of living with HF have been of great interest to nurse researchers who have explored these outcomes with both qualitative and quantitative methodologies.^33-43 Several quantitative studies have explored different factors thought to affect HRQoL. An issue for these studies is that different conceptualizations and measurement tools of HRQoL are used. The majority of studies define HRQoL as multidimensional and either use multiple instruments to measure different dimensions, or a single instrument that includes multiple components. These studies illustrate the importance of both psychological factors and physical factors in patient HRQoL. An additional issue is the inclusion of some variables as components of HRQoL, while in other studies the variables are evaluated separately for their effect on HRQoL.

Another important, but understudied, area affecting HRQoL is sexuality, with patients reporting (via interviews, focus groups, and questionnaires) loss of interest, decreased frequency, and sexual performance problems.^25,44-46 Sexual function was related to physical function, psychological distress, and other factors, and better sexual function was related to higher HRQoL.⁴⁶ These few studies point to a need to incorporate counseling and education on sexual functioning for HF patients and initiate more research in this area. Sexual issues and their effect on HRQoL may differ between men and women with HF, and gender differences in HRQoL in general have been explored with differing results.^47,48

Aerobic exercise is now a recommended therapy for HF patients, as it has been shown to be generally safe and well tolerated and to improve patient function and general well-being.⁴⁹ Nurse researchers have studied factors associated with exercise participation, developed programs of home exercise for patients, and determined the hemodynamic effects of resistance exercises.^50-52 Oka et al⁵² conducted a randomized clinical trial comparing the effects of a 3-month home-based combined walking and resistance exercise training with usual care in 40 adult HF patients. Evaluation at 3 months was conducted in 24 patients, with the exercise group showing improvements in HRQoL domains of emotional function and mastery and improvement in symptoms of fatigue and dyspnea.⁵² Although a promising start, these studies are small and relatively isolated. Larger trials of the effects of exercise on patient outcomes, how exercise may be incorporated into programs of care, and how exercise compliance can be improved are needed.

Psychosocial Issues

Other studies focused on a single psychological factor such as depression or psychological well-being rather than HRQoL, although symptoms and physical functioning were often evaluated for relationships with psychological variables. For example, both symptoms and physical function were moderately correlated with depression during hospitalization and 4 to 6 weeks after discharge in 170 HF patients.⁵³ Researchers who assessed 222 HF patients found that those with high levels of perceived control had significantly greater 6-minute walk distances and less emotional distress than did HF patients with low perceived control. Multivariate analysis was used to control for differences in demographic and clinical characteristics.⁵⁴ Understanding relationships among physical, psychological, and social factors in HF is important to support and intervene with patients appropriately, and to improve psychosocial factors and HRQoL.

Outcomes of HF Patients Treated With Surgical Therapies

Nurse sensitive healthcare outcomes of HF patients who require surgical interventions also have been examined. Despite aggressive therapies, patients with end-stage HF often continue to deteriorate and may be considered for implantation of a VAD and/or HT. The examination of healthcare outcomes in this section will focus only on this final group of advanced HF patients.

VADs have most commonly been used in patients with end-stage HF as a bridge to HT. Researchers have reported improved survival, hemodynamics, and end-organ function in patients with VADs awaiting transplant. In 2002, one of these devices was approved as destination therapy (permanently implantable device). The study of nurse sensitive outcomes is essential in these patients to increase our understanding of the risks and benefits of this therapy and to assist patients to achieve better outcomes.

Patients with end-stage HF (who may or may not have received a VAD) who meet clinical and psychosocial criteria may become candidates for HT. healthcare outcomes have been studied rather extensively in these patients since HT has been accepted as conventional therapy for NYHA class III-IV HF for several decades. Nurse sensitive healthcare outcomes studied in patients who require surgical therapies include HRQoL, symptom distress, functional status, psychological state, social interaction, occupational function, and compliance with the healthcare regimen.

Quality of Life and Life Satisfaction

The outcomes of morbidity and mortality are frequently reported but patients with advanced HF also report changes in quality of life (QoL) before and after left ventricular assist device (LVAD) implantation and HT. Nurses have contributed substantially to this body of knowledge. Patients (N = 30) have reported increased overall satisfaction with QoL (using the Quality of Life Index) and increased satisfaction with health, functioning, and significant others 2 weeks after LVAD implantation compared to before.⁵⁵ At 1 month after LVAD implantation, patients (N = 92) who were more satisfied with their QoL had less psychological distress and were African American.⁵⁶ Using multivariate modeling techniques, hospital discharge after LVAD implantation also contributed to satisfaction with life, specifically predicting increased satisfaction with social and economic aspects of life (N = 62).⁵⁷ Dew et al⁵⁸ reported that patient (N = 37) worries about device malfunction and infection were negatively correlated with overall QoL (using Campbell's 9-item scale to assess global well-being and life satisfaction). Patients (N = 40) who were bridged to HT were more satisfied with their overall QoL, health, and functioning 3 months after HT compared to 3 months after LVAD implantation.⁵⁹ While study designs were longitudinal, the studies were observational and exploratory. In addition, the number of individual studies was small, and these reports were most commonly from the same research group examining several domains of QoL after LVAD implantation at different time frames.

The only randomized clinical trial examining differences in survival, morbidity, and QoL outcomes in patients with advanced HF (who were randomized to LVAD implantation [n = 68] as destination therapy vs maximal medical therapy [n = 61]) was reported by the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) investigators.⁶⁰ Baseline QoL did not differ significantly between groups. One year later, LVAD patients (n = 23) reported significantly improved QoL compared to medically managed patients (n = 6).⁶⁰ Unfortunately, this study was limited by small sample sizes in both groups 1 year after study enrollment, primarily because of patient death.

Improvement in global QoL and overall satisfaction with life has also been reported from before to 1 year after HT (N = 148).⁶¹ When satisfaction with specific domains of QoL was further explored, patients reported significantly improved satisfaction regarding their health, functioning, psychological state, and socioeconomic status from before to after transplant.⁶¹ Importantly, researchers found that patients (N = 219) who were more seriously ill before HT experienced less improvement in global QoL after surgery and were less satisfied with their lives overall.⁶²

Symptom Occurrence and Distress

Symptom frequency and distress have been examined after LVAD implantation and HT, and most of these studies have been conducted by nurse researchers. At 1 to 2 weeks after LVAD implantation, symptom distress was low.⁵⁵ The most common symptoms were insomnia, fatigue, exertional shortness of breath, weakness, restlessness, anxiety, lower extremity swelling, early satiety, feeling lack of control over one's life, and sleepiness.⁵⁵ Importantly, total symptom distress and cardiopulmonary, gastrointestinal, and genitourinary symptom distress decreased significantly from before to after LVAD implantation.⁵⁵ In addition, physical symptom distress was significantly less 3 months after LVAD implantation compared to 3 months after HT in the bridge to transplant application.⁵⁹

Despite improvements in perceived overall QoL, symptom occurrence and distress after HT is common and is typically related to immunosuppression. Symptoms include increased appetite, weight gain, weakness, fatigue, lack of sleep, pain, changes in facial and body appearance, fragile skin, bruising, and tremors.^63-66 Interestingly, the most frequent symptoms were not necessarily the most distressing symptoms.

Data on symptom frequency and distress after LVAD implantation and after HT are derived from descriptive studies, using both new and established instruments with psychometric support. Reports of symptom distress after LVAD implantation included patients followed only a few months after LVAD implant; symptom experiences later after LVAD implantation require further study. Since there are many studies of overall symptom experiences after HT, important next steps include describing differences in symptom experiences by sociodemographic characteristics and developing intervention studies for symptom management.

Physical Function and Health Status

Physical function, a well-studied QoL domain, changes over time in both LVAD and HT patients. Physical function (measured using the Sickness Impact Profile [SIP]) improved from before to after discharge following LVAD implantation.⁵⁷ Early and progressive mobilization of VAD patients contributed to improvement in physical functioning including activities of daily living and exercise capacity.^67,68 After discharge, physical functional limitations were associated with device-related sleep disturbances, daytime device noises, device malfunction, and infection.⁵⁸ In a longitudinal study of 40 patients who had HT, patients reported less physical disability at 3 months after transplantation versus at 3 months after LVAD implantation.⁵⁹ In addition, similar improvements in physical function (also using the SIP) from 2 months to 1 year after transplant were found when VAD patients (N = 63) were compared to a matched group of non-VAD patients (N = 90).⁶⁹

Improvement in functional status (ie, physical function and perceived health status) has been more consistently detected than improvement in other outcomes up to 10 years after HT. Significantly improved perception of health status⁷⁰ and improved physical functioning have been reported in the areas of energy, pain, ambulation, mobility, sleep/rest, self-care, home management, and recreation up to 1 year after HT.^61,71,72 Improved physical functioning is adversely influenced by posttransplant complications (osteopenia, obesity, and acute rejection) during the first postoperative year.⁷³ No deterioration in functional status was found up to 5 years postoperatively.^71-74 Although long-term physical functional status (specifically, ability to perform activities of daily living) was found to be at near-normal levels,⁷⁵ patients reported that physical activity was the least frequently identified lifestyle activity at more than 5 years posttransplant (N = 47).⁷⁶ Sexual dysfunction^77,78 and menstrual dysfunction⁶³ were common problems after HT. Lastly, while functional status improved after HT, exercise capacity improved but did not reach normal levels.^79,80

Using observational and frequently cross-sectional study designs, significant improvements in physical functioning (using subjective, self-report instruments and objective measures including treadmill testing) were found after both LVAD implantation and HT. Despite these improvements, physical limitations after both surgical procedures were reported and provide direction for the development of interventions. Factors related to poorer physical functioning after LVAD implantation are very different than are factors associated with poorer physical functioning after HT. Understanding the surgery-specific physical limitations (eg, device-related sleep disturbances after LVAD implantation and the development of acute rejection after HT) contribute to the development of targeted interventions.

Psychological State and Social Interaction

Changes in psychological state, studied most commonly by nurses and psychologists, are evident in VAD and HT patients. Overall, early after LVAD implantation, patients had moderately low levels of stress and used more positive coping styles, which are reported as being more effective than negative coping styles.⁵⁵ Hospital discharge reduced stress⁵⁷ but postdischarge psychological distress was associated with VAD-induced sleep disturbances, VAD noises, and the worry about the potential for VAD malfunction and infection (N = 37).⁵⁸ VAD patients (n = 63) with transplantation experienced similar emotional well-being (stable or improved) and less anxiety compared to non-VAD patients (n = 90) after transplant.⁶⁹ Notably, these same VAD patients experienced more cognitive dysfunction (using the Mini-Mental Status Exam) than did the non-VAD patients after transplant.⁶⁹ It is important to mention that neurologic events, which may contribute to cognitive dysfunction, are related to the type of VAD implanted.⁸¹

Social interaction also has been examined by some research groups. No change in disability in social interaction (which was low to moderate) was detected from before LVAD implantation (N = 30) to 2 weeks after.⁵⁵ When both patient and caregiver perceptions of VADs were studied after LVAD implantation, researchers determined that concerns were similar between the groups.⁵⁸ When compared to non-VAD patients who had a transplant (n = 90), VAD patients (n = 63) were less involved in social activities and more socially withdrawn, although these effects were variable.⁶⁹

Psychological and social outcomes have also been examined after HT. Researchers have generally reported improvement in psychological outcomes from before to after HT,^72,82 although no change in the amount of stress and use and effectiveness of coping strategies was detected by one research group (N = 148).⁶¹ Despite overall improvement in psychological outcomes from before to after transplant, psychological disorders have been reported. The most common psychological disorders after HT are depression and anxiety.⁸³ The risk of experiencing these disorders appears to be higher in the first year after transplant versus subsequent years after transplant.⁸³ Risk factors for increased posttransplant psychological disorders include a pretransplant psychiatric history, female gender, longer hospitalization, and poor physical health and a lack of social support.⁸³ Disruption of social roles and relationships decreased over time after HT.^84,85

Several observational, longitudinal studies reported psychosocial problems at 3 or more years after HT. These studies used well-validated instruments. Similar studies have been done up to 1 year after LVAD implantation, but using smaller sample sizes; both well-validated and new instruments have been used. Understanding cognitive dysfunction, psychological disorders, and social problems that may arise after LVAD implantation and HT is necessary in developing interventions to improve outcomes.

Return to Work

There are more studies of return to work in HT patients than in VAD patients. There are anecdotal reports of VAD patients who have returned to work.⁸⁶ However, nonemployment was significantly related to cognitive status in VAD patients who subsequently had a transplant.⁶⁹ Also of note, stress related to work, school, and financial issues was significantly less in LVAD patients after HT.⁵⁹

Studies of return to work after HT have been done by social workers, physicians, and nurses. Not all HT patients return to work. Furthermore, return to work has not been shown to be related to length of time after HT.⁸⁷ An association between return to work and QoL has been demonstrated, with employed patients experiencing a better QoL than do unemployed patients.^88,89 Using a longitudinal design, a descriptive study of long-term employment follow-up reported employment rates of 69%, 69%, and 57% at 1 year, 5 years, and 12 years after HT, respectively.⁹⁰ Factors associated with poor employment rates have not been identified in these studies. Understanding relationships between employment and other clinical, physical, emotional, and sociodemographic factors will guide healthcare providers who assist these patients with return to work.

Patient Compliance

No studies were found of patient compliance after implantation of a VAD. Four research teams (led by nurses or psychologists) have examined compliance after HT. Noncompliance with taking medications (immunosuppressants and other), following medical procedures (taking vital signs, calling the physician or nurse with problems, and keeping appointments), and following healthy lifestyles (dieting, exercising, and abstaining from smoking) has been reported.^91,92 Rates of HT recipient noncompliance with healthy lifestyles have been reported to be higher than rates of noncompliance with other aspects of the medical regimen.^76,91,92 Risk factors for poor compliance include younger age, former behavior, psychological and social factors, more self-care disability, symptom distress, more complications, and time after transplant.^91-93 Lack of compliance with the healthcare regimen has been correlated with poor clinical outcomes.⁹³ The troubling finding of poor clinical outcomes in patients who were less compliant with the healthcare regimen points to the urgent need to develop and test interventions to help at-risk patients to improve outcomes after HT. The development of studies to examine patient compliance after LVAD implantation is also needed.

Gaps and Future Research of Outcomes in Medically Treated HF Patients

Because of the varied and complex issues associated with living with and medically managing HF, multiple gaps exist in the research. Knowledge in some areas is minimal and not well integrated with other outcomes. Except for randomized clinical trials of programs of HF care, intervention research is not well developed in HF nursing research. Programs of care have improved resource use and mortality, but there are still gaps related to defining essential elements, identifying which elements are most effective for which patients, determining how essential components might be dosed or stratified by patient risk, and determining appropriate preparation of nurses delivering the intervention. Can interventions to improve compliance, self-care, and HRQoL be integrated within these programs of care, and will that then change what patients need from the intervention?

Self-care includes compliance to therapy as well as the more complicated behaviors of symptom monitoring and management. Effective strategies for helping patient to monitor, recognize, and control symptoms, and intervene by at least seeking timely treatment are integral to optimal patient outcomes. Nursing research has demonstrated that symptom monitoring is difficult, that patients delay in seeking treatment, and that multiple factors are associated with these self-care behaviors. Nurses have developed instruments for measurement of self-care, but few intervention studies to improve self-care in HF patients have been conducted. The few interventions tested are promising, but further research is needed. The area of patient self-care is one in which nurses could be the leading researchers.

Quality of life is an important outcome for patients. Although much is known about measuring HRQoL and the factors that affect it, studies are heterogeneous in conceptualization of HRQoL and the instruments used to measure it. Variables found to affect HRQoL are diverse, and research is needed regarding whether changes in and interventions to change these variables then affect HRQoL. Less is known about the association between changes in HRQoL and changes in other important outcomes (eg, morbidity and mortality), and whether interventions to improve HRQoL are associated with improvements in other areas.

Other areas of importance have only been minimally studied. For example, cognitive function is often impaired in HF, and studies are needed to determine clinically useful screening methods, how cognitive impairment affects other patient outcomes, and useful strategies for patient education and self-management in those with cognitive deficits.

Gaps and Future Research of Outcomes in Surgically Treated HF Patients

There are many gaps in the study of nurse sensitive healthcare outcomes of HF patients who undergo surgical therapies. To date, all of the VAD outcome studies are observational and short term. In addition, the number of studies is very limited and primarily from 2 research teams conducting longitudinal studies. Although sample sizes were limited, these 2 teams used appropriate research methods and advanced statistical techniques to account for missing data (eg, patients who died after LVAD implantation or who had a transplant). Psychometric data were reported and supported for use of the new instruments by these research teams.

Specific outcomes for which there are limited or no data after VAD implantation include cognitive function, anxiety and depression, sleep disturbances, incisional pain, self-care and compliance with the post-VAD therapeutic regimen, physical rehabilitation, sexual activity, return to work/school, caregiver burden, and hospital length of stay and readmission rates. Once post-VAD outcomes are better understood, interventions to improve outcomes need to be tested. For example, parts or all of the following interventions are nurse sensitive: management of pain, incisional dressings, sleep disturbances, methods to enhance self-care, reduction of critical care and hospital length of stay, and reduction of caregiver burden. In addition, as newer generation VADs become available, additional outcome and intervention studies will be needed, as each device has its own risks and benefits.

There are also gaps in the literature for patients who undergo HT. Most of the outcomes studies were done within the first 5 years of HT, although these patients are living longer. These studies often did not address differences in outcomes by age, gender, race, culture, socioeconomic status, or complications. Furthermore, research reports have inconsistently provided information regarding missing data or used advanced statistical techniques to handle missing data. The few studies beyond 5 years posttransplant had small sample sizes and often used cross-sectional designs. Also, there are few intervention studies reported in the literature.

Specific nurse sensitive outcomes of HT recipients that require further study include symptom management, physical rehabilitation, sexual and menstrual dysfunction, anxiety and depression, employment disability and return to work, neurocognitive dysfunction, and interventions to improve compliance with the transplant regimen. In addition, the relationship between nurse sensitive outcomes and clinical outcomes including morbidity and mortality needs to be further explored. For example, pretransplant obesity is a risk factor for increased morbidity and mortality after HT.⁹⁴ Interventions to reduce body weight and maintain weight reduction while listed for HT are well within the realm of nursing practice. Thus, while there has been more research of nurse-sensitive outcomes after HT as compared to after LVAD implantation, further study is needed for both surgical therapies.

Summary

The state of nursing science for patients with HF is evolving, with some areas being more mature than others. To move the science forward, a concerted effort by nurse researchers and other clinicians is required. Systematic reviews and meta-analyses would be useful to synthesize study findings in specific areas and more clearly delineate the gaps in knowledge. Studies should be replicated in different settings with varied populations. Evidence to change nursing practice and inform health policy needs to be widely disseminated, and guidelines for evidence-based nursing practice need to be developed and implemented. Nursing research has contributed greatly to our understanding of the impact of HF and its therapies on patient outcomes and interventions to improve these outcomes. Tremendous opportunities and many challenges still exist before we have a mature nursing science.