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Ann Thorac Surg 2004;77:1321-1327
© 2004 The Society of Thoracic Surgeons
a Rush University Medical Center, Chicago, Illinois, USA
b St. Luke's Medical Center, Milwaukee, Wisconsin, USA
c Sharp Memorial Hospital, San Diego, California, USA
d University of Pennsylvania, Philadelphia, Pennsylvania, USA
e University of Alabama, Birmingham, Alabama, USA
f Temple University, Philadelphia, Pennsylvania, USA
g University of Minnesota, Minneapolis, Minnesota, USA
h St. Vincent's Hospital, Darlinghurst, Australia
Accepted for publication September 22, 2003.
* Address reprint requests to Dr Grady, Section of Cardiology, Rush Heart Failure and Cardiac Transplant Program, Rush University Medical Center, 1725 West Harrison, Suite 439, Chicago, IL, USA 60612-3824
e-mail: kgrady{at}rush.edu
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Abstract |
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METHODS: A nonrandom sample of 78 patients who received a HeartMate vented electric left ventricular assist device (primarily middle-aged, white married males) who had quality-of-life data at 1, 2, 3, 6, 9, or 12 months after implant was the subject of this report. The sample size decreased with time primarily because of heart transplantation. Patients completed the following booklets of questionnaires: Quality of Life Index, Rating Question Form, Heart Failure Symptom Checklist, and Sickness Impact Profile. Analyses included both descriptive analyses and modeling procedures (mixed-effects models and Cox proportional hazards models).
RESULTS: Quality-of-life outcomes were fairly good and stable from 1 month to 1 year after HeartMate vented electric left ventricular assist device implantation. Both positive and negative changes were detected in all quality-of-life domains (physical and occupational function, social interaction, somatic sensation, and psychological state) after left ventricular assist device insertion. Items from the physical domain of quality of life, specifically walking and dressing oneself, were significantly associated with the risk of dying after left ventricular assist device implantation.
CONCLUSIONS: Identifying poor quality-of-life outcomes within 1 year after left ventricular assist device implantation provides direction to develop strategies to improve outcomes. Physical and occupational rehabilitation, psychosocial intervention, and monitoring symptom distress and physical disability may contribute to improved quality-of-life outcomes and survival after left ventricular assist device implantation.
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Introduction |
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On the basis of the REMATCH trial results, the US Food and Drug Administration approved the use of the HeartMate vented electric (VE) LVAD (Thoratec Corporation, Pleasanton, CA) as permanent therapy (ie, destination therapy) for patients with end-stage heart failure who are not candidates for heart transplantation. Thus, the continued study of outcomes, including QOL, in VE LVAD patients has become even more imperative. Given that the ventricular assist devices received by patients in the studies by Dew and associates [4, 6] were from several different manufacturers (not including the HeartMate VE LVAD) and the report on QOL outcomes in the REMATCH trial was only at baseline and 1 year later and was limited by increasingly smaller sample sizes with time, we believe that our prospective, longitudinal study of QOL outcomes in HeartMate VE LVAD patients from 1 month to 1 year after surgery will provide important, additional understanding of patient outcomes during the first postsurgical year. Thus, the purpose of our study was to describe change with time (from 1 month to 1 year) in patients who received a HeartMate VE LVAD as a bridge to heart transplantation and to identify QOL predictors of survival after LVAD implantation. Quality of life was defined as "the functional effect of an illness and its consequent therapy upon a patient, as perceived by the patient" [8]. The dimensions of QOL that we measured were physical and occupational function, psychological state, social interaction, and somatic sensation [8].
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Material and methods |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Instruments
Booklets of QOL instruments were completed by patient self-report at all time periods. Instruments were selected based on our definition of QOL, the domains of QOL that we believed were important to measure, appropriateness of these tools for this population of patients, and support for reliability and validity. The instruments that we selected were the Quality of Life Index [9], Rating Question Form [10], Heart Failure Symptom Checklist [11], Sickness Impact Profile [12], LVAD Stressor Scale [1], and Jalowiec Coping Scale [13]. Authors, number of items, QOL domains measured, subscales, and scoring are provided for each tool that is used for this report in Table 1.
Each instrument was printed on a different color of paper and bound into a booklet of instruments that were ordered differently for each time period to reduce the effects of fatigue, response bias, and sensitization. Demographic and clinical data were gathered by means of chart review at each time period. Support for reliability and validity of these instruments has been demonstrated in patients with chronic illnesses, including patients with heart failure who underwent mechanical assist device implantation and heart transplantation (Quality of Life Index [1, 14, 15], Rating Question Form [10], Heart Failure Symptom Checklist [1, 11, 16], and Sickness Impact Profile [1, 17, 18]).
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Statistical methods
Analyses were performed in SAS 8.0 (SAS, Cary, NC), S-Plus 6.1 (Insightful Corporation, Seattle, WA), and MIXOR (mixed-effects ordinal regression; [19]). Distribution of responses was summarized using frequencies, means, and standard deviations. Mean item, subscale, and total scale scores were converted to proportional scores by dividing by the maximum possible score. Patterns of change were examined graphically.
The significance of interval changes was tested using mixed-effects models [20]. We tested whether the group of indicators as a whole contributed significantly to the model fit and also reported on individual transitions that were significant. Models were fit on the full 1-year follow-up data and as a sensitivity analysis on a restricted data set including only the first 6 months of follow-up. Mixed-effects models that included random intercepts were fit using lme in S-Plus. Ordinal mixed-effects models were fit using mixed-effects ordinal regression. Significance levels are reported for all p values 0.05 or less. In light of the multiple models fit, we consider p values of 0.01 or less to be statistically significant.
Cox proportional hazards models were used to test for significant predictors of survival. Fifteen total scale and subscale scores were identified as candidate predictors. These were tested for the proportional hazards assumption, and cutoffs were established above which the risk of death appeared to be elevated. Multivariate models were fit for each scale. Those predictors significant in these analyses were then pooled, and a multivariate model was fit representing the best predictors from all scales. Finally, individual items within significant subscales were examined. Significance for predictors in the survival analysis was set at 0.05.
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Results |
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During the course of the study, subjects progressed from LVAD implant to heart transplant or death at different times. Figure 1 displays the number of subjects according to their study status at each of the QOL assessments. There are a total of 78 patients at each time period. At 1 month after LVAD implantation, all patients continued to receive LVAD support, and the majority of patients (n = 55 of 78 [71%]) had available booklet data for analyses. With time, the number of patients on LVAD support decreased, and the number of patients who underwent heart transplantation increased. This sample progression was expected as these patients were implanted with an LVAD as a bridge to transplantation. The percentage of available data relative to the number of subjects who could provide data at each point from 1 month to 1 year after LVAD implantation averaged 71%. Thus, changes in QOL variables with time are in part because of the selective removal of subjects from the total sample owing primarily to heart transplantation.
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Two significant differences were detected for patient satisfaction with time. Mean satisfaction with health and functioning increased from 1 month to 2 months after LVAD implantation (0.58 ± 0.18 versus 0.66 ± 0.16; p = 0.01), and mean satisfaction with significant others (ie, spouse, children, and friends) decreased from 3 months to 6 months after LVAD implantation (0.85 ± 0.14 versus 0.82 ± 0.17; p = 0.002). Otherwise, no significant differences were detected with time in patient satisfaction with life overall and by the other two subscales (Table 2). Generally patients were quite satisfied with life overall (range, 0.68 to 0.74) and with significant others (range, 0.79 to 0.87), socioeconomic areas of life (range, 0.63 to 0.77), psychological areas of life (range, 0.63 to 0.71), and health and functioning (range, 0.58 to 0.68; 0 = very dissatisfied and 1 = very satisfied for all) from 1 month to 1 year after LVAD implantation. Individual items of greatest satisfaction common to all periods (after rank ordering the means for all items and dividing the total number of items on the instrument into thirds) were the health care patients received (range, 0.89 to 0.96), faith in God (range, 0.88 to 0.97), emotional support received from others (range, 0.81 to 0.92), and relationship with one's spouse or partner (range, 0.85 to 0.92; 0 = very dissatisfied and 1 = very satisfied for all). Individual items of least satisfaction common to all periods were usefulness to others (range, 0.55 to 0.83) and the amount of control one had over one's life (range, 0.50 to 0.83; 0 = very dissatisfied and 1 = very satisfied for both).
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Functional disability was also examined for change with time. Two differences in disability by subscale from 1 month to 1 year after LVAD implantation were detected as seen in Table 4. Disability related to home management and work decreased significantly from 3 months to 6 months after surgery (0.46 ± 0.31 versus 0.33 ± 0.25; p = 0.007, and 0.48 ± 0.16 versus 0.42 ± 0.17; p = 0.002, respectively). In addition, there were trends toward decreased self-care disability from 1 month to 2 months after device implant and disability related to sleep or rest from 6 months to 9 months after LVAD implantation. A trend toward increased disability related to social interaction and physical activity was noted from 9 months to 12 months after LVAD implant.
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Quality-of-life predictors of survival
Possible QOL predictors of survival were identified through 12 months after LVAD implantation. Of the 15 scales and subscales that were candidate survival predictors, ambulation and self-care were individually significant. Two items from the ambulation subscale were associated with an increased relative risk: "can only walk short distances/need to stop and rest more" and "need cane/walker/crutches to walk around, or need to hold on to walls." If both were positive, relative risk increased by a factor of 3.0 (95% confidence interval, 1.9 to 4.7). Of the two, the first is the stronger predictor (relative risk, 2.1; 95% confidence interval, 1.2 to 3.8). From the self-care subscale, only one item by itself, "can dress self but only very slowly," was associated with an increased relative risk (1.9; 95% confidence interval, 1.1 to 3.4). However, the predictors from the two subscales are correlated and cannot be considered independent predictors of mortality. The utility of identifying these items is not to provide a substitute for medical indicators of risk but rather to provide caregivers with warning signals that are simple to observe.
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Comment |
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TopAbstractIntroductionMaterial and methodsResultsCommentAcknowledgmentsReferences |
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Because of the broad scope of this study, we performed many significance tests. The difference between statistical significance versus clinical importance is difficult to determine. Our use of a more stringent level of statistical significance for the mixed-effects modeling procedures decreased the likelihood of falsely claiming significance and increased the amount of change with time considered to be significant. Thus, we recognize that our results are primarily exploratory in character and most importantly provide direction for future research.
The somatic sensation domain of QOL changed early after LVAD implantation. Between 1 month and 3 months after LVAD implantation, neurologic symptom distress decreased, and there was a trend toward decreased overall physical symptom distress. Although many neurologic symptoms were present in all periods (at a low level of distress), only fatigue decreased significantly with time. These changes may reflect ongoing adaptation to having an LVAD.
The psychological domain of QOL was generally good whereas the social domain was more variable. Overall QOL was generally good, stress levels were moderate, patients were coping quite well, and patient satisfaction with psychological areas of life was good. Psychological symptom distress also decreased later after implant. Nonetheless, at all periods, patients reported negative emotions including feeling anxious, sad, helpless, and depressed. Thus, psychological monitoring and intervention may be indicated. Further research of the psychological effects of having an LVAD implant is highly recommended.
Social interaction was ranked highest for satisfaction between 1 month and 1 year after LVAD insertion. Highest ranked items from the Quality of Life Index that were common to all periods support this finding, including satisfaction with one's faith in God, relationship with one's spouse or partner, and emotional support from others. Similarly, we have previously reported that discharge predicted decreased family-related stress [3]. Dew and coworkers [21] also reported improved social functioning in discharged LVAD patients (n = 10) as compared with hospitalized LVAD patients (n = 25).
Negative change in satisfaction with social relationships was also detected after LVAD implantation. Patients reported decreased satisfaction with significant others between 3 months and 6 months after surgery and being least satisfied with usefulness to others for all time periods. Perhaps being at home for several months with an LVAD contributed to these negative changes in perception. Interestingly, Dew and associates [21] reported that LVAD outpatients (n = 10) were less likely to report being a burden to their families than were LVAD inpatients or transplant candidates. However, data from the study by Dew and colleagues [21] were generated from LVAD patients who were approximately 2 months after implant whereas our data are from a later time frame. Clearly, this is an area for monitoring, especially after a few months at home, regarding the need for possible psychosocial intervention and for future study.
The QOL domain of physical and occupational function also changed with time. Although overall perception of health status was described as fairly good, and patients perceived that they were doing well on the LVAD through 1 postoperative year, satisfaction with health and functioning increased further between 1 month and 2 months after surgery. We have previously reported improved satisfaction with health and functioning from before to early after LVAD implantation [1]. Furthermore, physical functional disability was low and remained stable through 1 year after LVAD implant.
The areas of work, home management, and recreation (from the Sickness Impact Profile) were ranked as the areas of greatest disability that were moderate or less. We have previously reported no change in these areas from before to early after LVAD insertion [1], but have found improvement in home management and the ability to work between 3 months and 6 months after surgery in the current report. Nonetheless, disability in these areas suggests the need for physical and occupational therapy after LVAD implantation. It is also important to note that these patients were listed for transplantation, and regarding return to work, patients may not have planned to resume employment until after heart transplantation. Assessment and development of interventions to improve outcomes in the domain of physical and occupational function after LVAD implantation requires further research.
Three items from two subscales (ambulation and self-care) of the Sickness Impact Profile were associated with an increased mortality while on an LVAD by a factor of 2 or more. Being able to walk only short distances with a need to stop or rest more, needing assistance to walk around, or being able to dress oneself, but more slowly, are classic indicators of unstable chronic heart failure [22]. The usefulness of these items in patients with LVADs is a logical extension of their usefulness as indicators of destabilized heart failure as they may be potential indicators of right heart failure or LVAD malfunction.
We acknowledge that our study has limitations. First, only 78 of 150 enrolled subjects were the basis for this report, drawn from a population of 281 HeartMate LVAD patients. Patients who were not enrolled in the study either died after LVAD implantation and before study enrollment or were too ill to be enrolled. Thus, our sample of 150 patients represents subjects who survived surgery and were well enough to participate in the study. In addition, 64 patients who received HeartMate implantable pneumatic LVADs were not included in this report because the focus of our analyses was on patients implanted with a long-term device approved by the US Food and Drug Administration in 2002 for destination therapy. Second, we acknowledge a decreasing sample size with time. However, as stated previously, our decreasing sample size was expected as these patients were awaiting heart transplantation. To deal with this issue (given that the sample size decreased the most more than 6 months after surgery), models were fit for both 1 month to 6 months and for 1 month to 1 year to detect differences in patterns that supported our use of modeling procedures through 1 year after implant. Lastly, not all patients with HeartMate VE LVADs were able to complete questionnaires at all periods. Because one reason for failure to complete study questionnaires was that patients were not well enough to do so, we may also be overestimating QOL.
In conclusion, we have shown that QOL outcomes are fairly good and stable from 1 month to 1 year after HeartMate VE LVAD implantation and that items from the physical domain of QOL, specifically walking and dressing oneself, are significantly associated with the risk of dying after LVAD implantation. Although both positive and negative changes were detected in all domains of QOL—physical and occupational function, social interaction, somatic sensation, and psychological state—it is important to note that these changes are exploratory and require further study. Furthermore, identifying negative change in QOL outcomes, whether they are consistently poor or have the potential to become more negative at various times within 1 year after LVAD implantation, provides direction to develop strategies to improve outcomes. Physical and occupational rehabilitation, psychosocial intervention, and monitoring symptom distress and physical disability may contribute to improved QOL outcomes and survival after LVAD implantation.
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Acknowledgments |
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