Serial Change in Health-Related Quality of Life Over 1 Year After Transcatheter Aortic Valve ImplantationPredictors of Health Outcomes
Author + information
- Timothy A. Fairbairn, MB, ChB⁎,
- David M. Meads, MSc†,
- Adam N. Mather, MB, BS⁎,
- Manish Motwani, MB, ChB⁎,
- Sue Pavitt, PhD‡,
- Sven Plein, PhD⁎,
- Daniel J. Blackman, MD§ and
- John P. Greenwood, PhD⁎,⁎ (j.greenwood{at}leeds.ac.uk)
- ↵⁎Reprint requests and correspondence:
Dr. John P. Greenwood, Department of Cardiology, G Floor, Jubilee Wing, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, United Kingdom
Abstract
Objectives The goal of this study was to assess serial changes in patient health-related quality of life (HRQOL) over time and identify predictors of patient benefit.
Background Severe aortic stenosis reduces the length and quality of a patient's life. Transcatheter aortic valve implantation (TAVI) is superior to standard medical therapy and noninferior to surgical aortic valve replacement for 1-year mortality. HRQOL is an important outcome measure for which there is limited evidence in TAVI populations.
Methods A total of 102 patients (mean age 80 ± 0.6 years; 49% male) undergoing TAVI consented to participate. Two HRQOL questionnaires—the social functioning (SF)-12v2 with physical component summaries (PCS) and mental component summaries (MCS) and the EQ-5D (with a visual analog scale [VAS])—were completed at baseline, 30 days, 6 months, and 1 year according to the recommendations of the Valve Academic Research Consortium. A SF-6D utility measure was calculated from the SF-12 survey.
Results HRQOL significantly improved over 1 year (PCS p = 0.02; EQ-5D p = 0.02; VAS p = 0.01; SF-6D p = 0.03), becoming similar to age-adjusted U.S. population norms. The greatest change occurred from baseline to 30 days (p < 0.001), with further significant improvements to 6 months (p < 0.01). An insignificant decline occurred between 6 months and 1 year (p > 0.05), but a linear pattern of change remained for PCS, EQ-5D, and VAS (p < 0.05). Male sex (SF-6D p = 0.01) and increased operator experience (PCS, EQ-5D, and VAS p < 0.05) were independent predictors of a greater improvement in HRQOL.
Conclusions HRQOL significantly improved early after TAVI and was maintained out to 1 year. Patient factors, procedural complications, and operator experience are predictors of health benefit at 1 year.
Symptomatic aortic stenosis (AS) reduces the quality and duration of an individual's life. Transcatheter aortic valve implantation (TAVI) is indicated as a treatment for the large number of patients with severe AS unsuitable for surgical aortic valve replacement (SAVR) (1). Clinical trial and registry data have demonstrated high procedural success, significantly improved survival compared with medical therapy, and noninferiority in mortality to SAVR at 1 year (2–4). Health-related quality of life (HRQOL) assessments are important clinical outcome measures of medical treatments. The Valve Academic Research Consortium recommended that quality of life questionnaires be used as a TAVI clinical benefit endpoint and that they should be conducted over 4 separate time points (baseline, 30 days, 6 months, and 1 year) (5). Quality of life is particularly relevant for TAVI patients; in an elderly population with multiple comorbidities, the absolute survival benefit may be less substantial, increasing the importance of quality-attained years. In addition, identification of particular risk factors and predictors of HRQOL would allow the “heart team” to better inform patients of their likely individual benefits from this high-risk procedure.
Health utility values are a measure of preferences for health states, which are essential for the calculation of quality-adjusted life-years (QALYs) within the framework of cost-utility analyses. Cost-utility analyses are the preferred approach, with QALYs the preferred metric of organizations charged with evaluating the cost-effectiveness of medical technologies for the purpose of healthcare resource allocation and decision making (6).
Quality of life data on TAVI populations are sparse (7,8), and at the time of writing, only the PARTNER study has published HRQOL results over the range of recommended time points (9), with no reports of health utility values for this patient group. Health utility values, especially multiple assessments over a long time period, are important to allow cost-effective analyses and decision analytical modeling to be undertaken.
The goals of this study were to assess serial changes in HRQOL and health utility at 30 days, 6 months, and 1 year after TAVI and to identify the clinical variables that predict patient benefit.
Methods
A total of 102 patients who underwent TAVI at our institution between May 2008 and May 2010 provided written informed consent to the study, which was approved by the institutional ethics committee and performed in accordance with the Declaration of Helsinki. Patient selection for TAVI was performed by a multidisciplinary heart team that included a cardiologist, cardiothoracic surgeon, and cardiac anesthetist. Using echocardiography, severe AS was defined as a peak velocity >4 m/s or a calculated aortic valve area <0.8 cm2. All individuals were symptomatic and deemed unsuitable for SAVR due to high calculated surgical risk (EuroSCORE >20) or inoperable comorbidities. Pre-operative assessments included invasive angiography of the coronary and iliac arteries and transesophageal echocardiography. Patients were deemed unsuitable for TAVI if the aortic annulus was <20 or >27 mm. Exclusion criteria were the inability to comprehend English language or impaired cognition.
Transcatheter aortic valve implantation
TAVI was performed under general anesthesia using the 18F CoreValve Revalving System (Medtronic, Inc., Minneapolis, Minnesota) as described previously (10). A transfemoral approach was used where possible, with percutaneous access and closure. A surgical subclavian approach was performed in patients without suitable femoral access. Aortic valvuloplasty under rapid pacing control was followed by CoreValve implantation (26 or 29 mm) with post-dilation as required. The primary operator was identical for all procedures, and the results reflect all cases sequentially performed after proctorship.
Quality of life assessments
HRQOL was assessed using 2 generic, validated questionnaires: the SF-12v2 health outcomes questionnaire (QualityMetric Inc., Lincoln, Rhode Island) and the EQ-5D questionnaire (EuroQOL). Each patient completed a questionnaire at baseline, 30 days, 6 months, and 1 year. The initial survey was conducted by interview with a trained health care specialist, and later time points were completed by postal or telephone survey. Patient characteristics, comorbidities, New York Heart Association (NYHA) functional class, procedural risk factors, and variables were collected before TAVI. Post-operative complications (e.g., vascular hemorrhage, permanent pacemaker implantation) and mortality were collected post-TAVI.
The SF-12v2 is based on the 36-item Short-Form Health Survey but is shorter and simpler to complete and is thus more suitable to an elderly population. It uses 8 dimensions to assess HRQOL: physical functioning (PF), role physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), role emotional (RE), and mental health (MH). Responses applied to the patient's health over the previous 4 weeks. These responses were then graded and scored from 0 to 100, with a higher score reflecting a better HRQOL. In addition, 2 separate component summary scores are provided, distinguishing between physical (physical component score [PCS]) and mental (mental component score [MCS]) health.
EQ-5D and SF-6D are 2 health-based utility measures. Utility measures typically provide an index (quality of life weighting) between 0 and 1, where 1 reflects full health and 0, death. Utility values are combined in economic evaluations with survival data to calculate QALY gains from new treatments and technologies. EQ-5D uses 5 domains to assess health states: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. It is scored using the U.K. population tariff time-tradeoff valuation exercise. Patients also completed a visual analog scale (VAS) of worst imaginable (0) to best possible (100) health. Answers applied to the day of completing the questionnaire. SF-6D is a utility-based measure that is calculated using the SF-12 scores converted to SF-6D utility scores using a U.K. tariff (11). This provides an additional domain (vitality) and different recall period (4 weeks) from the EQ-5D. Differences in the change of scores suggest that SF-6D has a higher sensitivity in severe disease processes (12).
In this TAVI population who were in generally poor health, the use of both EQ-5D and SF-12 surveys is complementary; EQ-5D is more suitable for a population with poor health because it demonstrates a ceiling effect in moderately severe health conditions, whereas SF-12 reportedly underestimates the severity of health status in poorer health groups but does not demonstrate a ceiling effect (12).
Statistical analysis
Continuous data are presented as mean ± SD and categorical data as frequency and percentage. Normality was determined by using the Shapiro-Wilks test and Q-Q plots. Comparative statistics used were the Student t test and Wilcoxon signed rank test as appropriate. All paired comparisons between baseline measurements and the various time points were performed analysis by analysis, excluding unpaired results. The chi-square test was used for categorical comparisons. Repeated measures analysis of variance (ANOVA) general linear model was applied to detect changes over the 4 time points and differences between subject factors. Predictors of the 1-year health scores were assessed by using individual linear regression analysis, with baseline scores entered as a covariate factor. Individual variables with a p value <0.1 were entered into the multivariate general linear model. All statistical analyses were performed using PASW software version 17.0 (SPSS Inc., Chicago, Illinois); a 2-sided significance level of p < 0.05 was considered statistically significant.
Results
All 102 patients completed baseline HRQOL questionnaires. Three patients had valvuloplasty instead of TAVI, giving a 97% procedural success. The study population therefore consisted of 99 patients (mean age 80 ± 6 years; 49% male); clinical and procedural characteristics are reported in Table 1. All-cause mortality was consistent with the published literature; 3 (3%) at 30 days, 7 (7%) at 6 months, and 20 (20%) at 1 year (12). Three patients (3%) were unable (due to cognitive decline) and 4 (4%) unwilling to complete all 4 time point questionnaires. Incomplete questionnaires, including those as a result of patient death, were excluded from subsequent time point ANOVA analysis. Table 2 shows the health score results for each survey according to the Valve Academic Research Consortium–recommended time points, with the U.S. population norms stratified for age (80 to 89 years) to allow comparison with an equivalent age group of healthy individuals (13).
Baseline Demographic, Clinical, and Procedural Characteristics of the TAVI Population (N = 99)
Health Scores for Each Health Survey According to the VARC- Recommended Time Points (Baseline, 30 Days, 6 Months, and 1 Year) and U.S. Population Norms
SF-12 health scores
The separate health component scores over the 4 different time points are shown in Figure 1. Components that increased significantly from baseline to 30 days included: PF (27.8 ± 7 vs. 33.6 ± 9; p < 0.001), RP (31.8 ± 8 vs. 35.8 ± 10; p = 0.006), BP (38.9 ± 14 vs. 45.9 ± 12; p = 0.001), GH (33.4 ± 10 vs. 40.3 ± 11; p < 0.001), VT (36.8 ± 9 vs. 41.2 ± 10; p = 0.006), and MH (45.2 ± 11 vs. 48.5 ± 11; p = 0.027). SF (37.4 ± 14 vs. 39.7 ± 13; p = 0.22) and RE (39.2 ± 12 vs. 40.8 ± 15; p = 0.75) improved but not significantly. At 6 months, there was a further increase from 30 days in PF (36.5 ± 12; p < 0.001), RP (39.3 ± 10; p < 0.001), VT (43 ± 11; p = 0.002), SF (42.8 ± 15; p = 0.06), and RE (42.6 ± 13; p = 0.67). BP and GH scores did not increase further but remained significantly higher than baseline (45.4 ± 13 [p = 0.02] and 40.8 ± 11 [p = 0.001]). One-year measurements revealed a nonsignificant (p > 0.05) decrease in all components when compared with 6-month scores, with a sustained improvement compared with baseline scores in PF (34.9 ± 10; p < 0.001), RP (36.2 ± 10; p = 0.03), GH (38.8 ± 11; p = 0.003), and VT (40.2 ± 10; p = 0.03). Repeated measures ANOVA showed a significant improvement over the 4 time points to 1 year for all PCS scores (PF, RP, BP, and GH) but not for the MCS scores (VT, MH, SF, and RE).
Changes in SF 12 Health Component Scores After TAVI
Time points are represented by different-colored bars. BP = bodily pain; GH = general health; MH = mental health; NS = not significant; PF = physical functioning; RE = role emotional; RP = role physical; SF = social functioning; VT = vitality. P values by repeated measure analysis of variance: *p < 0.05, **p < 0.01, ***p < 0.001.
The summary score for physical health (PCS) increased from baseline (29.5 ± 9) to 30 days (36.3 ± 9; p < 0.001) and 6 months (38.3 ± 11; p < 0.001). One-year PCS, although lower than the 6-month score, was still significantly higher compared with baseline (34.4 ± 10; p = 0.02) (Table 2). Repeated measures ANOVA in those patients who completed surveys at all 4 time points (n = 65) demonstrated a significant linear (p = 0.03) and quadratic (inverted U-shaped curve p < 0.001) relationship over time (Table 3). Overall MCS showed no significant change from baseline to any of the individual time points (30 days p = 0.47; 6 months p = 0.71; and 1 year p = 0.58) (Table 2), which was confirmed on repeated measures ANOVA (p = 0.13) (Table 3).
Serial Change in Health Scores for Each Health Survey (Baseline, 30 Days, 6 Months, and 1 Year) in Patients Who Completed Questionnaires at all 4 Time Points
Utility assessment scores
EQ-5D and VAS scores increased significantly from baseline to 30 days (0.54 ± 0.3 vs. 0.65 ± 0.3 [p < 0.001] and 51.1 ± 21 vs. 61.4 ± 21 [p < 0.001], respectively). These scores improved further at 6 months (0.68 ± 0.3 [p = 0.006] and 68.2 ± 20 [p = 0.008]), with a small insignificant decrease at 1 year (0.65 ± 0.3 [p = 0.94] and 61.5 ± 21 [p = 0.70]) (Table 2). One-year measures remained significantly higher than baseline for both EQ-5D and VAS scores (p = 0.02 and p = 0.01). Repeated measures ANOVA demonstrated a significant linear and quadratic relationship over the 4 time points for both EQ-5D (p = 0.04 and p = 0.02) and VAS (p = 0.02 and p = 0.002) scores (Table 3). SF-6D increased from baseline to 30 days (0.60 ± 0.1 vs. 0.66 ± 0.1; p = 0.001) and was maintained at 6 months (0.68 ± 0.1; p = 0.001) and 1 year (0.63 ± 0.1; p = 0.03) (Table 2). Repeated measures ANOVA again showed a significant quadratic relationship over the 4 time points (p = 0.004) (Table 3).
HRQOL changes related to patient and procedural characteristics
All variables were assessed for predictors of change in HRQOL from baseline to 1 year using a general linear model. Age was considered as a linear variable as well as being categorized into groups of <80 years or ≥80 years. Independent predictors of HRQOL change at 1 year are reported for the separate questionnaires in Table 4. MCS values have not been reported because there were no significant predictors of change.
Predictors of 1-Year Quality of Life
Male sex was an independent predictor of greater improvement in HRQOL at 1 year (SF-6D) (Table 4). There was no sex difference in HRQOL scores at baseline, but at 1 year, males had significantly higher HRQOL compared with females (SF-6D 0.69 ± 0.1 vs. 0.58 ± 0.1; p = 0.001) (Fig. 2A). Males had significantly worse baseline left ventricular ejection fraction (p = 0.004) and higher incidence of previous myocardial infarction (p < 0.001), with no difference between other characteristics (EuroSCORE, age, or operation order).
Patterns of Health Change Over 1 Year According to Subgroup Analysis
(A) Change over time for SF-12, EQ-5D, visual analog scale (VAS), and SF-6D according to sex. (B) Change over time for SF-12, EQ-5D, VAS, and SF-6D for individuals age <80 years or ≥80 years. Continued on next page.(C) Change over time for SF-12, EQ-5D, VAS, and SF-6D according to operation order (group 1 = first 50 cases; group 2 = last 49 cases). PCS = physical component score.
Health changes also differed between age groups. The younger age group (<80 years) compared with the older group (≥80 years) reported lower baseline health scores (EQ-5D 0.45 ± 0.3 vs. 0.58 ± 0.3 [p = 0.04]; VAS 43 ± 25 vs. 54 ± 20 [p = 0.02]; and SF-6D 0.56 ± 0.1 vs. 0.61 ± 0.1 [p = 0.03], respectively) with no difference between their health scores at 1 year (EQ-5D 0.67 ± 0.3 vs. 0.63 ± 0.3 [p = 0.51]; VAS 58 ± 21 vs. 64 ± 20 [p = 0.29]; and SF-6D 0.64 ± 0.1 vs. 0.63 ± 0.1 [p = 0.70]) (Fig. 2B).
Other than prior coronary artery bypass graft predicting a greater improvement in HRQOL, no other specific pre-existing comorbidity predicted 1-year HRQOL. Those patients with higher baseline NYHA and angina class had a lower baseline HRQOL, although these findings were not significant (p = 0.55 and p = 0.48, respectively). Pre-operative NYHA functional classes III and IV patients did, however, experience a smaller increase in their HRQOL score compared with those individuals in NYHA classes I and II (Table 4).
HRQOL changes related to operative variables
Operator experience affected HRQOL (Table 4). Operative order was separated into 2 groups: the first 50 (group 1) and subsequent 49 (group 2) procedures. Patients in group 2 had a greater increase in all 4 health survey scores (PCS, EQ-5D, VAS, and SF-6D) at 1 year. Group 2 patients had insignificantly higher baseline health scores compared with group 1, which increased further, becoming significantly different at 1 year (PCS p = 0.003; VAS p = 0.02; EQ-5D p < 0.001; and SF-6D p = 0.01) (Fig. 2C). Vascular hemorrhage was an independent predictor of lower EQ-5D at 1 year, with no other specific procedural complication (transfusion or aortic regurgitation) resulting in a significant decline in HRQOL scores (Table 4).
Discussion
In a high-risk AS population, we found serial improvements in quality of life sustained over 1 year after TAVI. Benefit was seen early (at 30 days post-procedure) and increased further at 6 months. An insignificant drop in health status occurred between 6 months and 1 year, which seemed to be related to both patient and procedural factors. Male sex was an independent predictor of a greater increase in health score from baseline to 1 year. We have also shown for the first time that the “learning curve” of operator experience affected the health benefits for patients, independent of other procedural factors or complications.
Quality of life is an important clinical outcome measure of TAVI because patients are elderly, often frail, and have multiple comorbidities. This study demonstrated the change in HRQOL over time post-TAVI, with the greatest change from baseline being observed at the 30-day time point. This finding may be explained by certain early benefits from the less invasive nature of TAVI (compared with SAVR), such as shorter hospital stay, rapid hemodynamic response, and reduced mortality (3–5,7–15). Health scores increased further from 30 days to 6 months, with an insignificant decline between 6 months and 1 year for all surveys. In separate studies, HRQOL post-TAVI has previously been shown to improve at the individual time points of 30 days, 5 months, or 1 year (7,8,16) and over a series of time points (9), but our study is the first, to our knowledge, to show a pattern of health change over time as recommended by the Valve Academic Research Consortium for both health and utility measures. When compared with the age-matched general U.S. population norms, the baseline health of our TAVI population seemed considerably worse. This improved up to 6 months, where the average health was better than the general U.S. norm for PCS, EQ-5D, and VAS with similar scores in MCS and SF-6D. The small drop in reported health between 6 months and 1 year, which although statistically insignificant, may reflect a decline in health that could become significant over a longer time period (e.g., 2 years). This observation is important in determining the health outcome post-TAVI and would suggest that future studies should involve long-term (>1 year) follow-up.
An important finding of this study is that various subgroups within the TAVI population had different health responses. One of the major driving forces in the development of TAVI was to aid in the treatment of elderly patients with severe AS, who with high levels of morbidity and mortality were not receiving SAVR (17). This observation was despite the evidence that SAVR improves relative survival (18,19) and quality of life in octogenarians (20,21). Our study is concordant with that of Bekeredjian et al. (22), which found that HRQOL improves post-TAVI in individuals age ≥80 years. In addition, we demonstrated that younger patients (age <80 years) actually have lower baseline health scores yet gain equal benefits from the procedure. This is important because in the future, TAVI may be performed on a younger population. Higher baseline health scores in the older age group may seem counterintuitive, but age itself does not affect HRQOL. It is the associated diseases and loneliness which prevail in the elderly that reduce HRQOL (11). Our age groups (<80 and ≥80 years) had similar baseline comorbidities, and thus the elderly population may perceive their health to be relatively higher due to lower expectations.
Females with AS have a decreased survival compared with males that is predominantly due to lower referral rates for SAVR because once operated on, they have similar mortality outcomes (23). TAVI data have not demonstrated any sex differences in clinical outcomes such as mortality or stroke, but no one has previously assessed this in relation to HRQOL as an outcome measure. Despite having a slightly higher rated baseline health, females improved less significantly than their male counterparts, with the difference becoming significant at 1 year. This finding was not related to any differences in baseline demographic characteristics or to the operative procedure. Although not formally assessed in this study, it may reflect a greater prevalence of frailty in elderly female patients.
Operator experience has been reported to adversely affect procedural success, cardiovascular outcomes, and 30-day survival after the TAVI procedure as a result of a learning curve and device developments (24,25). We describe for the first time the impact of this learning curve on HRQOL as a clinical outcome. Multivariate analysis showed operator experience to be a predictor of health outcomes in 3 of 4 health surveys, independent of baseline patient characteristics (age, sex, and comorbidities) and procedural complications. A change in the patient selection process that is not identified by using standard risk scores or associated comorbidities such as frailty could have contributed to this observation, as may be suggested by the insignificantly higher baseline health scores of patients in group 2. Because an identical valve device was used in all subjects and the procedure was performed by a single primary operator, device technological developments are excluded as a possible explanation for a difference in health benefit over time. Although not identifying a “critical number” of procedural experience required, this finding does provide further evidence to support the training and performance of TAVI in high-volume centers with experienced operators to maximize the improvement in patient outcomes.
Patient selection remains one of the most challenging areas of TAVI practice. Our results provide evidence that a higher NYHA functional class predicts a less substantial improvement in health, whereas previous patient coronary artery bypass graft leads to a greater improvement in HRQOL. These factors, if confirmed in larger studies, could contribute toward the heart teams' TAVI patient selection criteria and aid the decision-making process for the individual patient.
The published TAVI data have demonstrated improvement in patient survival and symptoms, but it remains a costly procedure with a significant post-procedural risk of death, vascular hemorrhage, and stroke (3). Cost-effectiveness and the calculation of QALYs will therefore form an important part of health policy planning and outcome measurement in TAVI clinical practice. Until now, no health utility measures have been reported in a TAVI population. In our study, a significant improvement occurred over 1 year for both utility measures, which also showed a similar pattern of change. Further investigation is required to establish if the improvement in health of our study population, when combined with improved mortality rates, will indicate a health economic benefit of TAVI.
Study limitations
Although the study cohort was representative of a typical TAVI population, this was a single-center study in the United Kingdom and, as with all quality of life studies, it should be interpreted in the context of the local population. The interpretation of the multivariate analysis is limited by a reduced sample size at 1 year (n = 65). As future TAVI numbers increase, larger studies will be required to validate our findings. A surgical comparison group was not recruited given the difficulty in matching to a TAVI population for age, comorbidities, and risk factors; this difficulty was a consequence of the current guidelines for TAVI patient selection. Incomplete questionnaires secondary to cognitive decline (3%) may indicate a reduced quality of life that has not been calculated. This study was not designed to perform a cost-effectiveness analysis or calculate QALYs from the health utility data. Ideally, any future study should combine both aspects in a multicenter, international registry to provide more comprehensive information to allow future health policy planning.
Conclusions
Quality of life improved early after TAVI and was maintained out to 1 year. Population subgroups respond differently to TAVI (e.g., males had larger health improvements). Increased operator experience was a predictor of greater improvement in patient's quality of life, independent of other patient or procedural variables. Health utility measures showed a similar pattern of increased patient health out to 1 year and could in the future be combined with mortality data to produce a comprehensive health benefit model for TAVI.
Footnotes
Dr. Plein has received a research grant from Philips Healthcare. Dr. Blackman is a proctor for Medtronic, Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- ANOVA
- analysis of variance
- AS
- aortic stenosis
- BP
- bodily pain
- GH
- general health
- HRQOL
- health-related quality of life
- MCS
- mental component score
- NYHA
- New York Health Association
- PCS
- physical component score
- QALY
- quality-adjusted life-year
- RE
- role emotional
- RP
- role physical
- SAVR
- surgical aortic valve replacement
- SF
- social functioning
- TAVI
- transcatheter aortic valve implantation
- VT
- vitality
- Received December 6, 2011.
- Revision received January 10, 2012.
- Accepted January 25, 2012.
- American College of Cardiology Foundation
