Quality of life in female lung transplant candidates and recipients

The Quality of Sex Life Among Patients Before and After Lung Transplantation: A Single-Center Study

BACKGROUND

Lung transplantation (LTx) is the only effective method of treatment for patients with end-stage lung diseases; LTx prolongs and increases the quality of life (QoL). An important aspect of QoL that changes in the course of severe diseases is the quality of sex life. This aspect is yet to be discussed in relationship to LTx. We aim to compare patients' quality of sex life at the qualification process with patients' who underwent LTx.

METHODS

The studied group consisted of 100 patients (24 women before and 16 after LTx, 39 men before and 21 after LTX) who were admitted to the lung transplantology department for qualification or to control the function after LTx. To assess the patients' quality of sex life, we used The Changes in Sexual Functioning Questionnaire (CSFQ) and World Health Organization (WHO) QoL-BREF. To assess lung function, patients underwent a 6-Minute-Walk-Test (6MWT).

RESULTS

Patients after LTx obtained higher results-compared to patients qualified for LTx-in the WHO QoL-BREF in every domain (somatic, psychological, social, and environment). Men after LTx got more points in every domain and better total score (53 ± 5.62 vs 44.23 ± 10.28 point; P < .05) in CSFQ. Women before and after LTx obtained comparable results in CSFQ. Results of 6-Minute-Walk-Test were better among patients after LTx than in qualified patients (523.62 ± 95.71 vs 333.14 ± 145.38 and 524.12 ± 56.17 vs 317.20 ± 141.6, respectively for men and women).

CONCLUSIONS

Patients after LTx show better pulmonary function and quality of sex life than qualified. Preliminary results encourage us to conduct research on a larger group.

Avoidant Coping with Health Problems is Related to Poorer Quality of Life among Lung Transplant Candidates

Context

Lung transplant candidates face numerous health-related stressors. Although previous work has described the range of coping strategies candidates may use, whether those strategies are related to quality of life in physical functioning, emotional, and social domains has rarely been examined.

Methods

Adult lung transplant candidates (N=128) participated in semistructured interviews that included questions regarding global and domain-specific quality of life and a multidimensional assessment of coping with health-related problems. Demographic characteristics, health status, and other psychosocial variables were also assessed, and their effects were examined and controlled in multivariate analyses of the coping–quality-of-life relationship.

Results

Respondents were most likely to use active, acceptance, and support-seeking strategies to cope with health problems. Self-blame or avoidance were rarely used. Although used least often, avoidant coping was the most strongly and consistently related to quality of life. With demographic and psychosocial variables controlled, higher avoidant coping remained associated with significantly poorer global quality of life, bodily pain, difficulty with daily work or activities as a function of emotional problems, and depressive symptomatology. Avoidant coping accentuated the association of poor health status and lower quality of life. Among respondents with lower health status, using more avoidant coping was associated with greater difficulty functioning in daily activities as a result of emotional problems. Those with higher health status had less difficulty functioning in daily activities as a result of emotional problems.

Conclusions

Transplant team members are encouraged to be aware of and help patients refrain from using avoidant coping strategies.

Desire for Control, Coping, and Quality of Life in Heart and Lung Transplant Candidates, Recipients, and Spouses: A Pilot Study

To understand the interdependence of couples involved in transplantation, both partners need to be included in the same study. This pilot study explored the desire for control, coping, and quality of life in heart and lung transplant candidates, recipients, and spouses, using McCubbin's Double ABCX Model as the conceptual basis. Sixty letters were mailed to randomly selected candidates and recipients at 2 transplant centers. Twenty-five couples completed a demographic sheet and the following surveys: The Desire for Control Scale, the Family Crisis Oriented Personal Evaluation Scale, and the Quality of Life Index. There were 9 pretransplant and 16 posttransplant couples. Analyses included measures of central tendency, analysis of variance, t tests, and correlations. There were statistically significant differences between pretransplant patients' quality of life and all other groups. There were moderate correlations between several patient and spouse variables. It was recommended that healthcare professionals include both patients and spouses when planning interventions.

To transplant or not? The importance of psychosocial and behavioural factors before lung transplantation

The gratifying results of lung transplantation in terms of survival and quality of life stimulate the referral of an ever-increasing number of patients with end-stage lung disease. This in turn compounds the organ shortage, which is the limiting factor in the transplantation rate. In the absence of good alternative treatment modalities, an evidence-based pretransplant screening process is a prerequisite to detennine which patients will benefit most from transplantation. Within this evidence-based screening process, medical selection criteria are well established. There is a growing awareness that psychosocial and behavioural factors may determine outcome after transplantation as well. This paper reviews the available evidence for psychosocial and behavioural factors in the screening process for lung transplantation. The relation of various factors with post-transplant outcome was explored. Psychosocial characteristics before transplantation consist of 1) anxiety and depression, 2) personality disorders, 3) neurocognitive problems, and 4) lack of social support. Pretransplant behavioural factors include 1) noncompliance with medication, 2) alcohol abuse or dependence, 3) smoking, 4) noncompliance with dietary guidelines, and 5) noncompliance with monitoring of vital parameters and infections. It appears that the lack of rigorous studies limit the feasibility of an evidence-based screening process. Prospective studies are crucial to this further investigation of the relationship between psychosocial and behavioural determinants before transplantation and outcomes after transplantation, in terms of compliance, morbidity, and mortality. Identification of modifiable risk factors for poor outcome before transplantation is a first step in developing interventions.

Characteristics of psychosexual functioning in adults with cerebral palsy

Objective: To investigate the characteristics of psychosexual functioning in adults with cerebral palsy, as compared with able-bodied control subjects, matched by gender and marital status, and to identify the factors affecting psychosexual functioning.

Design: Interview and survey using the Derogatis Sexual Functioning Inventory (DSFI).

Setting: Inpatient and outpatient units in a rehabilitation hospital and welfare facilities.

Subjects: Sixty-two adults with cerebral palsy and 142 age-matched able-bodied controls participated in this study. The participants were grouped into four subgroups according to gender and marital status.

Main measures: General characteristics of the subjects, 10 domain scores of the DSFI and Sexual Functioning Index (SFI) as a global score were assessed. The scores for each cerebral palsy group according to gender and marital status were compared with those of their corresponding able-bodied control group.

Results: Unmarried men with cerebral palsy demonstrated lower SFI and weakness in sexual information, experience, drive, attitude, psychological symptoms, affect and satisfaction, compared with unmarried able-bodied men (p B=0.05). In contrast to unmarried men, unmarried women did not reveal any significant differences in all but body image domain score (p B=0.05) between the groups. Married adults with cerebral palsy showed higher levels of psychological distress in both men and women and lower sexual satisfaction in women (p B=0.05). Nonambulatory people with cerebral palsy had significantly a lower sexual information, experience and satisfaction, and a lower SFI than ambulatory (p B=0.05). Barthel Index was significantly related to body image (p B=0.05). Psychosexual functioning was not significantly different according to cerebral palsy type.

Conclusion: This study revealed the characteristics on psychosexual functioning in adults with cerebral palsy, depending on gender and marital status. The results suggested that nonambulatory unmarried men with cerebral palsy were at high risk in terms of psychosexual dysfunction.

Sexuality Among Women Recipients of a Pancreas and Kidney Transplant

Significant improvements in health and quality of life generally follow organ transplantation; however, there is evidence that women who have received transplants experience difficulty with sexual function. The specific nature and extent of this difficulty has not been documented. The purpose of this study was to describe sexual functioning and sexual self-esteem among women recipients of a simultaneous pancreas and kidney transplant. Perceived effect of the transplant on sexualitywas also explored. Participants completed a questionnaire that measured their sexual functioning (including sexual difficulties), sexual self-esteem, illnesses, medications, and perceived effect of the transplant on sexuality. Data analysis revealed that only 39% of the women would be classified as having normal sexual functioning. The majority reported either some difficulty with sexual function (34%) or sexual dysfunction (27%). About one third of the women reported that transplantation had only positive effects on their sexuality, whereas 28% reported negative effects, and 29% reported no effect.

A systematic review of health-related quality of life and psychological outcomes after lung transplantation

BACKGROUND

Lung transplantation (LTx) aims to reduce physical disability and mental distress, extend survival, and improve health-related quality of life (HRQoL). In this systematic review we aimed to: (1) augment evidence regarding measures to assess HRQoL and psychological outcomes after LTx; and (2) summarize HRQoL and psychological outcomes after LTx.

METHODS

Validated and standardized instruments with well-known psychometric properties used for assessing HRQoL and psychological outcomes after LTx were identified by means of comprehensive literature searches of PsychINFO and Medline/PubMed, up through March 2014, using the following search terms in various combinations: lung transplantation; physical functioning; symptom experience; mental health; anxiety; depression; distress; social functioning; life satisfaction; and health-related quality of life.

RESULTS

The search strategy identified 371 titles and abstracts. Of these, 279 were retrieved for further assessment and 63 articles selected for final review. Thirty-nine studies were found for HRQoL, 15 for physical functioning, 5 for mental health and 4 for social functioning. A total of 50 psychometric instruments were encountered.

CONCLUSIONS

Considerable heterogeneity exists in methodology, operational concepts and applied outcome measures in the existing literature on HRQoL and psychological outcomes after LTx. Nevertheless, the studies generally point to significant improvements in both mental health and HRQoL post-transplant. Further research is warranted utilizing consistent outcome measures, including LTx-specific measures and longitudinal study designs.

A thematic analysis of quality of life in lung transplant: the existing evidence and implications for future directions

Health-related quality of life (HRQL) has been assessed in various lung transplantation (LT) investigations but never analyzed systematically across multiple studies. We addressed this knowledge gap through a systematic literature review. We searched the PubMed, CINAHL and PsychInfo databases for publications from January 1, 1983 to December 31, 2011. We performed a thematic analysis of published studies of HRQL in LT. Using a comparative, consensus-based approach, we identified themes that consistently emerged from the data, classifying each study according to primary and secondary thematic categories as well as by study design. Of 749 publications initially identified, 73 remained after exclusions. Seven core themes emerged: (1) Determinants of HRQL; (2) Psychosocial factors in HRQL; (3) Pre- and posttransplant HRQL comparisons; (4) Long-term longitudinal HRQL studies; (5) HRQL effects of therapies and interventions; (6) HRQL instrument validation and methodology; (7) HRQL prediction of clinical outcomes. Overall, LT significantly and substantially improves HRQL, predominantly in domains related to physical health and functioning. The existing literature demonstrates substantial heterogeneity in methodology and approach; relatively few studies assessed HRQL longitudinally within the same persons. Opportunity for future study lies in validating existing and potential novel HRQL instruments and further elucidating the determinants of HRQL through longitudinal multidimensional investigation.

Quality of recipient-caregiver relationship and psychological distress are correlates of self-care agency after lung transplantation

Self-care behaviors are crucial for following the complex regimen after lung transplantation, yet little is known about recipients' levels of self-care agency (the capability and willingness to engage in self-care behaviors) and its correlates. We examined levels of self-care agency and recipient characteristics (socio-demographics, psychological distress, quality of relationship with primary lay caregiver, and health locus of control) in 111 recipients. Based on Perceived Self-Care Agency scores, recipients were assigned to either the low- or high-self-care agency comparison group. Characteristics were compared between groups to identify characteristics likely to be associated with lower-self-care agency. Mean (SD) score for self-care agency (scale range, 53-265) was 223.02 (22.46). Recipients with lowest-self-care agency scores reported significantly poorer quality of caregiver relationships (p < 0.001) and greater psychological distress (p < 0.001). After controlling for psychological distress, the quality of the recipient-caregiver relationship remained significantly associated with self-care agency. Every one-point decrease in the quality of caregiver relationship increased the risk of low-self-care agency by 12%. Recipients with poorer caregiver relationships and greater psychological distress may need additional support to perform the self-care behaviors expected after lung transplantation.

Predictors and outcomes of health-related quality of life in caregivers of cardiothoracic transplant recipients

Cardiothoracic transplant programs generally require that transplant recipients have family caregivers to assist them posttransplant. The burden of caregiving on the family members remains poorly understood. If caregivers' well-being is compromised by caregiving, it may bode poorly for transplant recipients' own health in the long-term posttransplant. We examined caregiver health-related quality of life (HRQOL) during the first year after their family member's transplant, its predictors and its relationship to subsequent patient survival. Adult (aged 18+) caregivers of 242 cardiothoracic transplant recipients (lung = 134; heart = 108) completed assessments of demographics, psychosocial characteristics and caregiver burden at 2 months posttransplant, and HRQOL at 2, 7 and 12 months posttransplant. Recipients' survival time was obtained from medical records. Caregiver HRQOL was generally high across the first-year posttransplant in emotional and social functioning; caregiver physical functioning significantly worsened. There were no differences by type of recipient transplant. Greater caregiver burden predicted poorer caregiver HRQOL in several physical domains at 12 months posttransplant. Transplant recipients whose caregivers had lower perceived general health at 12 months posttransplant showed poorer survival rates during the subsequent 7 years of follow up. Transplant teams should identify those caregivers at risk for poorer general health posttransplant to maximize positive outcomes for the entire family.

Negative Effects of Pretransplant Body Mass Index on Physical Health—Related Quality of Life after Lung Transplant

Background

Although current national data show improved graft and patient survival following lung transplant, the effects of several modifiable preexisting comorbid conditions on health-related quality of life after transplant have not been evaluated. This study examines the effects of 3 comorbid conditions present before lung transplant (reduced bone density, diabetes mellitus, and elevated body mass index) on health-related quality of life after lung transplant.

Methods

The Short Form 36 Health Survey was completed by 92 adult recipients at various times after lung transplant (mean, 41 months; range, 1–127 months). Multiple linear regression models that controlled for underlying disease, chronic rejection, and time after transplant tested the independent effects of the 3 pretransplant conditions on posttransplant health-related quality of life.

Results

The effects of pretransplant reduced bone density and diabetes mellitus were not statistically significant in these models. However, pretransplant body mass index had a significant negative effect (β = −.29, P = .007) on posttransplant physical health–related quality of life. Additionally, overweight status and obesity exerted comparable independent negative effects ( P = .01 and P = .03, respectively) on the physical function scale of the Short-Form 36 Health Survey compared with persons who were underweight or normal weight before transplant.

Conclusions

Reevaluation of elevated body mass index before transplant as a risk for reduced physical quality of life after lung transplant should be considered.

Patient-reported outcome 2 years after lung transplantation: does the underlying diagnosis matter?

Purpose

Transplantation has the potential to produce profound effects on survival and health-related quality of life (HRQL). The inclusion of the patient’s perspective may play an important role in the assessment of the effectiveness of lung transplantation. Patient perspectives are assessed by patient-reported outcome measures, including HRQL measures. We describe how patients’ HRQL among different diagnosis groups can be used by clinicians to monitor and evaluate the outcomes associated with transplantation.

Methods

Consecutive lung transplant recipients attending the lung transplant outpatient clinic in a tertiary institution completed the 15-item Health Utilities Index (HUI) questionnaire on a touchscreen computer. The results were available to clinicians at every patient visit. The HUI3 covers a range of severity and comorbidities in eight dimensions of health status. Overall HUI3 scores are on a scale in which dead = 0.00 and perfect health = 1.00; disability categories range from no disability = 1 to severe disability <0.70. Single-attribute and overall HUI3 scores were used to compare patients’ HRQL among different diagnosis groups. Random-effect models with time since transplant as a random variable and age, gender, underlying diagnoses, infections, and broncholitis obliterans syndrome as fixed variables were built to identify determinants of health status at 2-years posttransplantation.

Results

Two hundred and fourteen lung transplant recipients of whom 61% were male with a mean age of 52 (19–75) years were included in the study. Chronic obstructive pulmonary disease and cystic fibrosis patients displayed moderate disability, while pulmonary fibrosis and pulmonary arterial hypertension patients displayed severe disability. Patients with chronic obstructive pulmonary disease had the worst pain level, whereas patients with pulmonary fibrosis had the worst emotion and cognition levels. A random-effect model confirmed that development of broncholitis obliterans syndrome was the most important determinant of health status (P = 0.03) compared to other variables, such as cytomegalovirus infections and underlying diagnoses.

Conclusion

Descriptions of patients’ HRQL among different diagnosis groups could be used by clinicians to assist individualized patient care.

Determinants of physical activity in daily life in candidates for lung transplantation

BACKGROUND

Participation in daily physical activity (PA) has never been objectively assessed in candidates for lung transplantation (LTx). The main research questions were: 1) How active are LTx-candidates in daily life? 2) What are determinants of activity behavior before LTX?

METHODS

Ninety-six candidates for LTx (diagnosis of COPD or interstitial lung disease; mean age 55 ± 7 years) underwent measurements of PA, pulmonary function, 6-min walking distance (6MWD), muscle force and health-status (SF-36 scale).

RESULTS

Patients were markedly inactive (5% of waking hours walking, 26% standing and 69% sedentary). Backward multiple regression identified 6MWD (expressed as % of predicted value; β = 73.0 steps, partial r(2) = 0.36, p = 0.00), a higher score on the energy/fatigue scale of the SF-36 (β = 28.6 steps, partial r(2) = 0.09, p = 0.00) and a higher expiratory muscle force (expressed as % of predicted value; β = 11.8 steps, partial r(2) = 0.05, p = 0.02) as determinants of daily steps. Minutes of mild to moderate (≥2 METs) activity were determined by 6MWD (expressed as % of predicted value; β = 2.14 min, partial r(2) = 0.30, p = 0.00), inspiratory muscle force (expressed as % of predicted value; β = 0.33 min, partial r(2) = 0.04, p = 0.05) and seasonal influences (spring/summer vs. autumn/winter: β = 18.95 min, partial r(2) = 0.04, p = 0.05). The overall fit of the models was r(2) = 0.50 and r(2) = 0.38, respectively.

CONCLUSIONS

The 6MWD was the main determinant of an inactive lifestyle in these patients. Respiratory muscle force, energy and fatigue and seasonal variations explained some additional variability in activity behavior. Patients should be encouraged to participate in interventions aimed at improving physical fitness and participation in daily physical activity before LTx.

Survival and quality of life of patients undergoing lung transplant

Lung transplant offers the hope of prolonged survival and significant improvement in quality of life to patients with advanced lung disease. However, the medical literature lacks strong evidence and shows conflicting information regarding the effects of lung transplantation on these outcomes. Tools that integrate survival and quality-of-life information allow for more comprehensive evaluations of the benefits and risks of lung transplant. Higher-quality information leads to improved knowledge and more-informed decision making.

Lung transplantation for cystic fibrosis

Lung transplantation is a complex, high-risk, potentially life-saving therapy for the end-stage lung disease of cystic fibrosis (CF). The decision to pursue transplantation involves comparing the likelihood of survival with and without transplantation as well as assessing the effect of wait-listing and transplantation on the patient's quality of life. Although recent population-based analyses of the US lung allocation system for the CF population have raised controversies about the survival benefits of transplantation, studies from the United Kingdom and Canada have suggested a definite survival advantage for those receiving transplants. In response to these and other controversies, leaders in transplantation and CF met together in Lansdowne, Virginia, to consider the state of the art in lung transplantation for CF in an international context, focusing on advances in surgical technique, measurement of outcomes, use of prognostic criteria, variations in local control over listing, and prioritization among the United States, Canada, the United Kingdom, and The Netherlands, patient adherence before and after transplantation and other issues in the broader context of lung transplantation. Finally, the conference members carefully considered how efforts to improve outcomes for lung transplantation for CF lung disease might best be studied. This Roundtable seeks to communicate the substance of our discussions.

Olfactory performance before and after lung transplantation: quantitative assessment and impact on quality of life

BACKGROUND

Although olfactory function significantly impacts quality of life (QoL) and factors that potentially interfere with the sense of smell are numerous in solid-organ recipients, no respective data exist for this population. In this study we investigate the olfactory function, QoL, and the accuracy of subjectively perceived olfactory dysfunction.

METHODS

Olfactory performance was assessed with the aid of a validated test battery (Sniffin' Sticks) in 70 randomly selected lung transplant recipients and 22 patients on the lung transplant waiting list. In addition to assess QoL, the Questions on Life Satisfaction Module (FLZ(M)) and the Hospital Anxiety Depression Scale (HADS) were used.

RESULTS

Waiting list patients and lung transplant recipients did not show differences in terms of demographic data and olfactory performance. Compared with a normative population, patients <55 years of age had a significantly lower olfactory performance both before and after lung transplantation. Scores for general life satisfaction, health life satisfaction, and depression were significantly better in lung transplant recipients. In the multivariate analysis, better olfactory performance was significantly associated with better QoL before and after lung transplantation. Self-estimation of olfactory performance had a sensitivity of 36% and a specificity of 78%, respectively, to detect hyposmia/anosmia in our population.

CONCLUSIONS

Although lung transplantation does not seem to have an impact on olfactory performance, sense of smell is significantly below the average in lung transplant recipients and patients on the waiting list. In both groups, olfactory performance is significantly associated with QoL. Furthermore, self-estimation of olfactory function shows inadequately low sensitivity and specificity.

Technology and outcomes assessment in lung transplantation

Lung transplantation offers the hope of prolonged survival and significant improvement in quality of life to patients that have advanced lung diseases. However, the medical literature lacks strong positive evidence and shows conflicting information regarding survival and quality of life outcomes related to lung transplantation. Decisions about the use of lung transplantation require an assessment of trade-offs: do the potential health and quality of life benefits outweigh the potential risks and harms? No amount of theoretical reasoning can resolve this question; empiric data are needed. Rational analyses of these trade-offs require valid measurements of the benefits and harms to the patients in all relevant domains that affect survival and quality of life. Lung transplant systems and registries mainly focus outcomes assessment on patient survival on the waiting list and after transplantation. Improved analytic approaches allow comparisons of the survival effects of lung transplantation versus continued waiting. Lung transplant entities do not routinely collect quality of life data. However, the medical community and the public want to know how lung transplantation affects quality of life. Given the huge stakes for the patients, the providers, and the healthcare systems, key stakeholders need to further support quality of life assessment in patients with advanced lung disease that enter into the lung transplant systems. Studies of lung transplantation and its related technologies should assess patients with tools that integrate both survival and quality of life information. Higher quality information obtained will lead to improved knowledge and more informed decision making.

Pretransplant variables associated with quality of life in liver transplant recipients

OBJECTIVE

With an increasing number of liver transplant recipients living, understanding quality-of-life issues is essential. Our goal is to identify pretransplant variables associated with post-transplant quality of life in liver transplant recipients.

METHODS

Three hundred and eight liver transplant recipients were administered the Short Form 36 and a basic demographical questionnaire. Variables associated with post-transplant quality of life were studied in a multivariate regression analysis. Interaction terms were used to examine effect modification.

RESULTS

Male gender, longer pretransplant work hours and interaction term between work hours and male gender were independently associated with Physical Functioning. Work hours positively correlated with Role-Physical, while viral hepatitis and ascites were negatively associated with Role-Physical. Ascites and viral hepatitis were independently negatively associated with Bodily Pain. Encephalopathy, hepatocellular carcinoma and viral hepatitis were independently associated with General Health. Ascites was also negatively associated with Social Functioning, Role-Emotional, Bodily Pain, General Health and Vitality. Viral hepatitis was negatively correlated with Vitality and Mental Functioning.

CONCLUSIONS

Pretransplant variables such as ascites, encephalopathy, hepatocellular carcinoma, viral hepatitis, work hours, time unable to work and gender were significantly associated with post-transplant quality of life in liver transplant recipients. Interventions addressing these issues may be initiated to improve the post-transplant quality of life.

Long-term health-related quality of life after lung transplantation: different predictors for different dimensions

BACKGROUND

Lung transplantation has proven to be an effective treatment option for patients with end-stage lung disease with profound effects on both survival and health-related quality of life (HRQL). Generally, studies have reported improved HRQL after lung transplantation. When assessing HRQL, physical, psychologic or social dimensions are usually included. However, it is unclear what predicts outcome, to what extent, and whether there are differences in predictors between dimensions of HRQL. Knowledge about these predictors may be useful when making choices regarding therapy. The research question in the present study was: What are the predicting variables of physical and psychologic dimensions of HRQL, and do they differ?

METHODS

Results from studies of the physical dimension (the Nottingham Health Profile's energy and mobility scales) and the psychologic dimension (Zung depression and STAI anxiety scores) from 140 transplanted patients with a maximum follow-up of almost 10 years were assessed using mixed-model analysis. For both dimensions, the following variables were tested for their predictive value: age; gender; diagnosis; year of transplantation; time on the waiting list; type of transplantation; bronchiolitis obliterans syndrome; and pre-transplant HRQL scores.

RESULTS

With regard to the physical dimension after lung transplantation, presence of bronchiolitis obliterans syndrome (BOS), age and pre-transplant scores on the measure under study were significant predictors for both energy and mobility. For mobility, gender appeared to be an additional predictor. With regard to the psychologic dimension after lung transplantation, BOS was a predictor for both anxiety and depression. Pre-transplant depression was an additional predictor for post-transplant depression, and age was an additional predictor for anxiety.

CONCLUSIONS

Several variables were identified that predicted HRQL after lung transplantation. These variables differed between the physical and psychologic dimensions. The presence of BOS was a predictor for both dimensions. The present findings may be helpful when choosing or developing interventions aimed at improving HRQL after lung transplantation.

Depression After Lung Transplantation: Causes and Treatment

During the postoperative course of lung transplantation, patients may experience depressive symptoms that negatively influence their ability to cope with the new organ, their adherence to rehabilitation and pharmacologic therapy, and their overall quality of life (QoL). To date, no review has explored the causes of depression following transplantation or the efficacy and safety of therapeutic interventions in this patient group. We conducted a comprehensive 1966-2006 MEDLINE, EMBASE, and PsycINFO search for studies of the causes and treatments of depression in lung transplant recipients. We identified 25 studies of variable methodologic quality. Depression rates are high among candidates for lung transplantation. In the short term, after surgery depressive symptoms remain low with an improvement in QoL, whereas in the long term (>3 years), the decline of functional status is associated with a dramatic increase in such symptomatology. Personality disorders, coping strategies, stressful life events, physical complications, corticosteroid medications, age, gender, and psychosocial support all play a central role in causing depressive states in lung transplant recipients. Serotonin reuptake inhibitors (SSRIs) and new-generation antidepressants (mirtazapine) represent the best therapeutic choices for this group of patients. The risk of serious drug-drug interactions should be carefully monitored by experienced clinicians. Complementary therapies and psychoeducational intervention also help recipients to strengthen their coping strategies, offering further advantages after transplantation. Additional well-conducted randomized controlled trials are needed to clarify the epidemiologic course of depression following lung transplantation and to tailor effective pharmacologic or psychological interventions accordingly.

Prevalence and impact of pain on the quality of life of lung transplant recipients: a prospective observational study

STUDY OBJECTIVE

To study the prevalence and impact of pain on the quality of life (QOL) of lung transplant recipients.

DESIGN AND PATIENTS

Prospective, observational, cross-sectional study. Ninety-six lung transplant recipients (> 3 months after transplantation) completed questionnaires measuring the severity and impact of pain (Brief Pain Inventory), anxiety (State Trait Anxiety Inventory), QOL (Short Form-36 version 2 [SF-36v2]), and depression (Beck Depression Inventory [BDI]).

SETTING

University medical center lung transplant outpatient clinic.

RESULTS

The prevalence of pain in lung transplant recipients was 49%. Patients with pain were older, more likely to have undergone unilateral lung transplantation (64% vs 40%, p = 0.03), and were more likely to have lung emphysema (55% vs 38%, p = 0.004). Only a pulmonary diagnosis of lung emphysema remained an independent predictor for postoperative pain in a logistic regression model. Average (+/- SD) score of the BDI was 9.6 +/- 7.8 and 5.8 +/- 5.8 (p = 0.005) for patients with and without pain, respectively. Patients with and without pain did not significantly differ in terms of anxiety. Pain-free patients had a significantly higher physical component score than patients with pain in the SF-36v2 (mean, 48.7 +/- 8.6 vs 38.6 +/- 9.8, p < 0.0001, respectively), while the mental component scores were not statistically different between the two groups.

CONCLUSIONS

Lung transplant recipients have a high prevalence of pain. Patients with lung emphysema as their preoperative diagnosis are more likely to have pain. The occurrence of pain is associated with a decreased QOL in lung transplant recipients.

Trajectories of change in quality of life in 12-month survivors of lung or heart transplant

Survival and functional outcomes for lung transplant recipients continue to lag behind those for heart recipients. Whether these poorer physical outcomes translate into poorer quality of life (QOL) for lung recipients relative to heart recipients is unknown. Lung versus heart transplant recipients' perceptions of QOL were longitudinally compared at three time-points across the first year posttransplant. Additionally, potentially important predictors of patient QOL were examined. Adult transplant recipients (N = 199) participated in semi-structured interviews that included measures of QOL, optimism, mastery, social support, religiosity and coping. Temporal patterns of QOL change were compared between lung and heart recipients who survived until 1 year posttransplant using mixed-model, hierarchical analysis of variance (ANOVA). Demographic and psychosocial predictors were examined with multiple regression analysis to identify the unique effects of each variable on QOL 1 year posttransplant. While heart recipients' QOL across several domains was higher shortly after transplant, lung patients' QOL improved and was equivalent to that of heart recipients by 1 year posttransplant. Greater optimism and support from friends predicted better QOL in physical, psychological and social domains. Conversely, avoidant coping strategies predicted poorer physical functioning. Thus, while clinical interventions designed to improve QOL posttransplant should be tailored to transplant recipients' initial psychosocial assets and liabilities, they need not be distinguished by transplant type.

Lung transplant recipients holding companion animals: impact on physical health and quality of life

Since lung transplant recipients are susceptible to infections and inhaled pollution, many centers warn against pets. However, data supporting this recommendation are lacking. Our program is less restrictive regarding pets. This study, for the first time, investigates the association of pets with physiological and psychological parameters in these patients. A questionnaire concerning pets was sent to 104 lung transplant recipients. Lung function tests, levels of exhaled nitric oxide (FE(NO)), need for antibiotic treatments and hospitalizations, creatinine clearance, body mass index (BMI) and demographic data were assessed. Additionally, the questionnaire of life satisfaction (FLZ), a question on summarized life satisfaction (LS), the life orientation test (LOT), the hospital anxiety depression scale (HADS) and the social support questionnaire (F-SozU) were assessed. Response rate was 86%. Fifty-two percent defined themselves as pet owners, whereas 48% did not. The two groups did not differ in demographic or physiological data. Significant differences in FLZ (79/65, p = 0.04), in LS (4.3/3.9, p = 0.01), LOT (32/29, p = 0.006) and F-SozU (4.5/4.2, p = 0.04) were found in favor of pet owners. In lung transplant recipients keeping pets the frequency of somatic complications is not higher compared to lung transplant recipients without pets. After lung transplantation, pets are associated with a better quality of life.

Health-related Quality-of-Life Determinants in Lung Transplantation

BACKGROUND

In light of recent reviews, we examined the effect of individual and clinical factors, associated with lung transplantation (LTx), on health-related quality of life (HRQL).

METHODS

HRQL was measured cross-sectionally on 34 candidates and 71 lung transplant recipients, using the Short Form 36-item questionnaire (SF-36), of the Medical Outcomes Study. Multivariate analysis was used to model each of the 8 SF-36 health domains as a function of individual determinants associated with LTx. The original model included: transplant status; age; gender; time since LTx; forced expiratory volume in 1 second (% predicted); type of LTx received; lung disease; whether within 1 month of the interview the participant was hospitalized; days in hospital (LOS); and whether infection or rejection occurred. Final models were chosen using a statistical cutoff of alpha < or = 0.10 to remain in the model.

RESULTS

After adjusting for important predictors, lung transplantation was positively associated with all domains (p < 0.005). Although time since transplantation negatively influenced the physical- and social-related domains (p < 0.05), the effect was small. Clinically meaningful effects on physical HRQL domains were observed with disease (p < 0.01), type of transplant received (p < 0.05) and hospital stay (p < 0.05). Gender played a role in mental health (p < 0.05).

CONCLUSIONS

Clinical events leading to hospitalization limit some HRQL domains. Different factors influence the physical, social and mental health domains, and thus future studies should focus on domain-specific variables to optimize HRQL. The HRQL benefit conferred from LTx renders it a worthwhile option for end-stage lung disease patients with important physical limitations.

Physical functional outcomes after cardiothoracic transplantation

The study of patient healthcare outcomes after cardiothoracic transplantation has increased substantially over the last 2 decades. Physical function after heart, lung, and heart-lung transplantation has been studied using both subjective and objective measures. The majority of reports in the literature on physical function after cardiothoracic transplantation are descriptive and observational. The purposes of the article are to review and critique the existing literature on cardiothoracic recipients' subjective and objective physical function, including respiratory function for heart-lung and lung transplant recipients. In addition, the literature on sexual function in cardiothoracic recipients is examined, the gaps in the literature are identified, and recommendations are given for future research.

Does lung transplantation improve health-related quality of life? The University of Florida experience

BACKGROUND

Health-related quality of life (HRQoL) is an important clinical end-point in evaluating the overall success of lung transplantation. The primary purpose of this study, therefore, was to document the degree of change in HRQoL in a sample of patients evaluated before and after lung transplantation.

METHODS

Sixty-six adults who underwent single or bilateral lung transplantation at the University of Florida between March 1994 and May 2001 completed assessments of HRQoL (SF-36 Health Survey, Transplant Symptom Frequency Questionnaire), both before and after transplant. Pre- and post-transplant assessments of forced expiratory volume in 1 second (FEV1) percent predicted and 6-minute walk test performance were also obtained.

RESULTS

HRQoL before transplant was significantly lower than in normative samples of chronic obstructive pulmonary disease (COPD) patients and adults in the general population. However, repeated measures analyses of co-variance showed significant improvements on 7 of 8 SF-36 sub-scales, as well as the physical component summary and the mental component summary. Improvements in FEV1 percent predicted and 6-minute walk test performance were also found. Patients with longer time since transplantation reported more frequent and problematic symptoms commonly associated with immunosuppression, including depression, headaches and changes in physical appearance, among others.

CONCLUSIONS

Lung transplantation appears to yield significant HRQoL benefits for patients. Many patients do, however, experience frequent symptoms associated with immunosuppression that may limit the full benefit of transplantation, and some of these symptoms appear to worsen over time. Future research efforts should focus on the development, implementation and evaluation of clinical interventions designed to optimize HRQoL both before and after lung transplantation.

Quality of life after lung transplantation: a cross-sectional study

BACKGROUND

The increase in life expectancy has raised the importance of quality of life after lung transplantation, although this issue has not yet been systematically investigated. The aim of this cross-sectional study was to provide an overview of quality of life in lung transplant patients.

METHODS

Between April and July 2001, a set of 4 questionnaires were given to all adult, German-speaking lung transplant recipients (n = 108; response rate 87% [n = 94]): St. George's Respiratory Questionnaire (SGRQ), a lung-specific health status instrument; the Short Form-36 (SF-36), a general quality of life measure; the Hospital Anxiety and Depression Scale (HADS-D) and a self-reported questionnaire concerning sexual functioning, physical symptoms, adverse effects of immunosuppression and satisfaction with outcome.

RESULTS

With regard to the SGRQ, all lung transplant recipients had significantly better scores, which reflected an enhanced quality of life compared with the reference value for patients with obstructive pulmonary disease (SGRQ: p < 0.001 in all sub-scales). The Hospital Anxiety and Depression Scale and the Mental Component Summary Scale of the SF-36 did not differ significantly compared with published normative data in the healthy population. However, the side effects of immunosuppression proved to be a major factor influencing the quality of life of lung transplant recipients (11% influenced strongly and 24% moderately). Seventy-six percent of lung transplant patients were highly satisfied with the transplant outcome and 92% would opt for the procedure again. Among all lung transplant recipients, those with cystic fibrosis were most satisfied (significantly) with their quality of life.

CONCLUSIONS

Although lung transplant patients must cope with the side effects of immunosuppression, they report a highly satisfying quality of life with regard to physical and emotional well-being and social and sexual function.

Quality of life and coping strategies among lung transplant candidates and their family caregivers

Although numerous studies have examined coping strategies and quality of life (QOL) among patients with chronic diseases and their family caregivers, no studies have examined the reciprocal effects of patient and caregiver coping strategies on their dyad partner's QOL. Because most people who cope with stressful health experiences do so within the context of interpersonal relationships, it is important to understand the ways in which the two partners' coping strategies may reciprocally affect each other's QOL. Adult lung transplant candidates and their caregivers (N=114 pairs) participated in semi-structured interviews that included measures of QOL and coping with patients' health-related problems. Multivariate, canonical correlation analyses were performed to examine unique patterns of associations between coping and QOL in patient-caregiver dyads. Better patient QOL, across multiple domains, was associated with better caregiver QOL. Multiple elements of patients' coping, including greater use of active coping and emotionally oriented coping were related to generally poorer patient QOL in psychosocial and physical domains. Similarly, caregivers who used more emotionally oriented coping had poorer QOL. There was no statistically reliable relationship between either (a) patient and caregiver use of coping strategies, or (b) caregiver coping and patient QOL. However, patients' coping strategies were important correlates of caregivers' QOL. These findings belie common clinical beliefs that family members' coping responses to patients' health are likely to affect patient well-being. Instead, patients' coping and QOL may be critical for understanding caregiver well-being, especially in the current era in which caregivers are assuming increased responsibility for providing patient care.

Psychosocial situation and physical health in 50 patients > 1 year after lung transplantation

BACKGROUND

Lung transplants have been performed worldwide since the early 1980s. While numerous studies have been published on somatic aspects after lung transplantation, there is considerably less information available on psychosocial aspects and on the correlation between the physical and the psychosocial state of health after transplantation.

METHODS

Between 1992 and 2002, 125 patients underwent lung transplantation at University Hospital Zurich. To be included into the study, patients had to have received a lung transplant > 12 months previously and to have good knowledge of the German or Italian languages. With the aid of standardized questionnaires, psychosocial variables such as levels of anxiety and depression, self-esteem, and social support were determined. In addition, self-assessments of physical and psychological health were obtained. The medical data included information on FEV1, complications such as pulmonary infections, acute or chronic allograft rejection, and assessment of the patient's physical and psychological health by the treating doctors.

RESULTS

The overall degree of anxiety and depression of the lung transplant recipients was comparable to standard samples of an average population. However, male lung transplant recipients were significantly more depressed than female recipients. Self-esteem was higher than in clinical comparison samples. Preceding pulmonary complications had long-lasting effects on the level of anxiety, whereas nonpulmonary complications did not have such an effect.

CONCLUSIONS

Overall, the psychological well-being of patients after lung transplantation is similar to the normal population. Subgroups of patients with increased psychological distress have been identified.

The effect of bronchiolitis obliterans syndrome on health related quality of life

Bronchiolitis obliterans syndrome (BOS) is the most important factor limiting long-term survival after lung transplantation, and has a substantial impact on patients' daily life in terms of disability and morbidity. Aim of our study was to examine the effects of BOS on health related quality of life (HRQL) in lung transplantation patients. Data on HRQL from 29 patients who developed BOS at least 18 months earlier were studied longitudinally. HRQL measures were: the Nottingham Health Profile (NHP), the State Trait Anxiety Inventory (STAI), the Self-rating Depression Scale (ZUNG), and the Index of Well Being (IWB). Furthermore questions concerning activities of daily life and dyspnea were asked. The majority of the patients were male, and the most common diagnosis was emphysema. After the onset of BOS, significantly more restrictions were reported on the dimensions energy and mobility of the NHP. These restrictions appeared to increase over time. After the onset of BOS, STAI scores remained more or less stable and close to the value of the general population. ZUNG scores were significantly higher after the onset of BOS, and patients experienced a lower level of well being than the general population. The percentage of patients that reported to be able to perform activities of daily life without effort declined dramatically after the onset of BOS. Furthermore, the percentage of patients complaining of dyspnea increased after the onset of BOS. In conclusion, our study showed that HRQL was negatively affected by the onset of BOS. However, in spite of these less favorable long-term results, even patients who develop BOS may at least temporarily benefit from a lung transplantation.

Quality of life after lung transplantation

Despite the potential differences in patient characteristics, study designs, and types of instruments used, this review of the literature showed several common findings. Important improvements in QOL are reported after lung transplantation. These improvements were observed when cross-sectional comparisons were made across the cohort of candidates and recipients and during longitudinal follow-up of patients at pretransplant and posttransplant time points. The improvements in QOL after transplantation seem to be sustained for at least 1 to 3 years after transplant. Lung transplant recipients generally were satisfied with their decision to have undergone transplantation. Many issues require further clarification. Variables that may influence QOL before and after lung transplantation, such as age, sex, pretransplant diagnosis, and type of procedure performed, should be considered carefully as study variables. Carefully designed, prospective longitudinal studies with many patients would result in stronger conclusions regarding the importance of QOL assessment in lung transplantation. It would be useful for a few QOL measurement tools to emerge as standard instruments so that many centers and investigators could adopt them to use independently. Standard instruments would allow comparison of outcomes between centers and would allow meta-analyses of multiple studies using the same methodology. Interpretation of the studies would be improved because there would be improved familiarity with a few tools, rather than vague recognition of a large variety of tools.

Improved quality of life after lung transplantation in individuals with cystic fibrosis

The aim of the present study was to assess the effect of lung transplantation (LgTX) on health-related quality of life (HRQL) in a group of patients with cystic fibrosis (CF), compared to patients with other diagnoses (non-CF). HRQL was assessed before transplantation in a group of 32 CF patients and 183 non-CF patients. After LgTX, we conducted a prospective longitudinal study among 10 CF patients and 35 non-CF patients who survived at least 31 months after LgTX. Measures were the Nottingham Health Profile (NHP), the State-Trait Anxiety Inventory (STAI), the Self-Rating Depression Scale (ZUNG), the Index of Well-Being (IWB), and the Karnofsky Performance Index. Patients in the CF group were younger, spent more days on the waiting list, and were more likely to be working or going to school than patients with other indications. Before transplantation, CF patients and non-CF patients experienced restrictions on almost all HRQL measures, compared to the general population. On the NHP dimensions of mobility and energy, CF patients had significantly better scores than non-CF patients. Between 1-4 months after transplantation, scores on the NHP, ZUNG, and Karnofsky performance indices improved, and STAI and IWB scores even occurred within the reference value in both groups. Significantly better scores in the CF group compared to the non-CF group were found on the NHP dimension of mobility 4 months after transplantation, and on the dimension of sleep 7 and 13 months after transplantation. Scores remained more or less stable over time in both groups. It may be concluded that patients in both groups experience major restrictions in HRQL before transplantation. However, pretransplant non-CF patients experience more restrictions than CF patients. After LgTX, both groups of patients showed substantial improvement in HRQL, and this improvement was maintained until 31 months after LgTX.

Avoidant coping with health problems is related to poorer quality of life among lung transplant candidates

CONTEXT

Lung transplant candidates face numerous health-related stressors. Although previous work has described the range of coping strategies candidates may use, whether those strategies are related to quality of life in physical functioning, emotional, and social domains has rarely been examined.

METHODS

Adult lung transplant candidates (N = 128) participated in semistructured interviews that included questions regarding global and domain-specific quality of life and a multidimensional assessment of coping with health-related problems. Demographic characteristics, health status, and other psychosocial variables were also assessed, and their effects were examined and controlled in multivariate analyses of the coping-quality-of-life relationship.

RESULTS

Respondents were most likely to use active, acceptance, and support-seeking strategies to cope with health problems. Self-blame or avoidance were rarely used. Although used least often, avoidant coping was the most strongly and consistently related to quality of life. With demographic and psychosocial variables controlled, higher avoidant coping remained associated with significantly poorer global quality of life, bodily pain, difficulty with daily work or activities as a function of emotional problems, and depressive symptomatology. Avoidant coping accentuated the association of poor health status and lower quality of life. Among respondents with lower health status, using more avoidant coping was associated with greater difficulty functioning in daily activities as a result of emotional problems. Those with higher health status had less difficulty functioning in daily activities as a result of emotional problems.

CONCLUSIONS

Transplant team members are encouraged to be aware of and help patients refrain from using avoidant coping strategies.

Long-term quality of life in patients surviving at least 55 months after lung transplantation

The aim of this study was to examine the long-term effect of lung transplantation on Health Related Quality of Life by studying 28 patients who survived at least 55 months after lung transplantation. Measures included the Nottingham Health Profile, questions concerning lung-specific problems, the State-Trait Anxiety Inventory, the Self-rating Depression Scale, the Index of Well-Being, the Karnofsky performance index, and questions concerning activities of daily life. Furthermore, comorbid conditions were measured. Before transplantation patients reported restrictions on almost all quality of life measures. Until approximately 43 months after transplantation there were significant improvements on most dimensions of the Nottingham Health Profile and more patients could walk without dyspnea. Significant improvements occurred with regard to the levels of anxiety, depression, and well being, and the scores on the Karnofsky performance index improved. Activities of daily life could be performed without help by most patients. After approximately 43 months patients experienced more dyspnea, anxiety, depression, and a lower level of well being. The number of patients suffering from a decrease of kidney function, drug treated hyperlipidemia, insulin dependent diabetes mellitus and bronchiolitis obliterans syndrome increased. It may be concluded that patients experience a stable and better overall quality of life after transplantation. Long-term after lung transplantation patients experience a decline on several dimensions of quality of life, which may be explained by an increase of comorbid conditions and Bronchiolitis Obliterans Syndrome.

Desire for control, coping, and quality of life in heart and lung transplant candidates, recipients, and spouses: a pilot study

To understand the interdependence of couples involved in transplantation, both partners need to be included in the same study. This pilot study explored the desire for control, coping, and quality of life in heart and lung transplant candidates, recipients, and spouses, using McCubbin's Double ABCX Model as the conceptual basis. Sixty letters were mailed to randomly selected candidates and recipients at 2 transplant centers. Twenty-five couples completed a demographic sheet and the following surveys: the Desire for Control Scale, the Family Crisis Oriented Personal Evaluation Scale, and the Quality of Life Index. There were 9 pretransplant and 16 posttransplant couples. Analyses included measures of central tendency, analysis of variance, t tests, and correlations. There were statistically significant differences between pretransplant patients' quality of life and all other groups. There were moderate correlations between several patient and spouse variables. It was recommended that healthcare professionals include both patients and spouses when planning interventions.

Care before and after lung transplant and quality of life research

Lung transplantation is a growing surgical option for patients with end-stage lung and pulmonary vascular diseases. After completing an extensive evaluation and meeting the selection criteria, patients are listed for either single or bilateral-sequential lung transplantation. Immediate postoperative management requires detailed attention to fluid management, monitoring for infection, reperfusion injury, pulmonary hygiene, and pain management. Length of stay depends on the patient's condition before transplant and postoperative complications. Discharge from the hospital can be as early as 7 days after transplantation. Newer immunosuppressive medications offer more options for treating and preventing rejection. Advanced practice nurses, such as coordinators, case managers, nurse practitioners, and clinical nurse specialists, are uniquely positioned to play key roles in coordinating the care of transplant patients across settings and both before and after the transplant procedure. The perioperative needs of lung transplant patients and the impact of this complex procedure on the recipients' and family's quality of life merit further investigation by clinicians and researchers.

Psychological functioning and quality of life in lung transplant candidates and recipients

OBJECTIVE

The purpose of this study was to examine the psychological functioning and quality of life (QOL) of lung transplant candidates and recipients.

METHODS

The following measures were completed by 36 lung transplant candidates (the pretransplant group [PRE]) and 73 recipients (the posttransplant group [POST]): the Rand-36 Item Health Survey 1.0 (RAND-36), visual analog scale of overall QOL (OQOL), Brief Symptoms Inventory (BSI), Derogatis Sexual Functioning Inventory (DSFI), Hospital Anxiety and Depression Scale (HAD), Rosenberg Self-Esteem Scale (RSES), and Body Cathexis Scale (BC).

RESULTS

Compared to the PRE, POST patients had significantly better scores on the following measures: RAND-36 total, physical health, role limitations due to physical health, general health, vitality, and social functioning subscales (all p < 0.0001); visual analog scale of OQOL (p < 0.0001); BSI (p < 0.05); BC (p < 0.05); HAD anxiety (p < 0.05) and depression (p < 0.0001); and RSES (p < 0.05). Despite better scores, some areas did not differ between the PRE and the POST, and many patients continued to experience impairments in psychological functioning. Specifically, the RAND-36 emotional health and role limitations due to emotional health subscale scores did not differ between the PRE and the POST and they remained lower than published norms. A significant proportion of patients in both groups (44% of PRE patients and 28% of POST patients) had borderline or clinical levels of anxiety (ie, the HAD). Finally, PRE and POST mean scores were significantly lower than published norms on the RSES (p < 0.05) and the body image scale of the DSFI (p < 0.05).

CONCLUSIONS

Although lung transplant recipients have better general, physical, and psychological health than their pretransplant counterparts, the present research suggests that both groups experience impairment in several areas of psychological functioning. Future research into the QOL of the lung transplant population should be aimed at recognizing, intervening, and improving patients' psychological and emotional well-being.

Research on the quality of life of lung transplant candidates and recipients: an integrative review

Although lung transplantation is one of the most rapidly growing areas of solid organ transplantation, there has been little research on the quality of life of lung transplant candidates or recipients. This review critiques and synthesizes the quality-of-life reports concerning these patients that have been published between January 1980 and January 1999. The purposes of this review of the literature were to (1) examine both the conceptual and operational definitions of quality of life used; (2) identify and list the instruments used to measure quality of life; (3) investigate methodologic issues; and (4) determine the state-of-the-art of research in this area. On the basis of this review, suggestions are made for future studies.