Chronic obstructive pulmonary disease (COPD) and heart failure (HF) are among the top four contributors to illness, disability, and death in our rapidly aging society (National Institutes of Health, 2016). Both comprise a huge socioeconomic burden, including intensive outpatient surveillance and care; medical treatment; and costly, prolonged hospitalizations. Exercise-based interventions aimed at COPD and HF populations with the goal of improving physical functioning and disease self-management have been shown to improve exercise performance, dyspnea and fatigue, illness exacerbation, quality of life, and healthcare costs in both groups (Fleg et al., 2015; Georgiou et al., 2001; Goldstein, Gort, Stubbing, Avendano, & Guyatt, 1994; Hui & Hewitt, 2003; McCarthy et al., 2015; Sagar et al., 2015). Physical activity, defined by the World Health Organization as any force exerted by skeletal muscles that results in energy expenditure above resting level (Cavill, Kahlmeier, & Racioppi, 2006), is becoming a key outcome of exercise interventions because inactivity is associated with increased morbidity and mortality in the elderly and those with cardiopulmonary illness (Manini et al., 2006; Waschki et al., 2011, 2015).
In the past decade, research has identified numerous similarities in the pathophysiological and functional concomitants of COPD and HF including histological and metabolic changes that are both cellular and systemic (Corrà et al., 2005; Debigaré et al., 2003; Gielen, Adams, Niebauer, Schuler, & Hambrecht, 2005; Gosker et al., 2003; Rehn, Munkvik, Lunde, Sjaastad, & Sejersted, 2012). Accordingly, investigators are recognizing the potential utility of the traditional pulmonary rehabilitation model to address the unique and complementary needs of HF and COPD patients (Evans, 2011; Louvaris & Vogiatzis, 2015; Muthumala, 2008; Troosters & Remoortel, 2009). Evans and colleagues (2010) investigated short-term exercise outcomes of an HF sample that underwent 14 two-hour sessions of endurance training over 7 weeks in an existing pulmonary rehabilitation program. Compared to a usual care no exercise group, the HF exercise participants made large short-term gains in exercise endurance and lesser, but significant, improvement in dyspnea, fatigue, and emotional function. Currently, relatively few patients with HF and COPD participate in cardiopulmonary rehabilitation, because these programs impose a significant time, travel, and financial burden. Outpatient programs of the traditional 8–16 weeks result in high attrition and inefficient use of program staff. An outcomes model simultaneously addressing needs of both diagnostic groups might improve program efficiency, while expanding the potential consumer base with cardiopulmonary illness.
The primary objective of this randomized controlled trial was to compare outcomes of a standard cardiopulmonary rehabilitation program with those of a shorter self-efficacy-based exercise adherence intervention. The purpose of this paper is to report baseline to post-intervention completion in functional capacity, daily activity, dyspnea symptoms, depression, quality of life, and cardiopulmonary function outcomes in the two rehabilitation programs. Secondarily, we describe differences in outcomes between those with severe HF with reduced ejection fraction (HFrEF) compared to those with severe COPD.
The conceptual framework and intervention elements are published in greater detail elsewhere (Dougherty, Steele, & Hunziker, 2011). Briefly, social cognitive theory provides two constructs of self-efficacy and self-regulation that formed the basis for the intervention. Self-efficacy is the sense of confidence to perform specific behaviors, the strength of which determines whether activities will be attempted, the duration and magnitude of effort to overcome obstacles to successful performance, and associated anxiety and distress (Bandura, 1997). Efficacy expectations are increased through four mechanisms: (1) performance attainment, (2) vicarious experiences, (3) verbal persuasion from expert sources, and (4) minimizing emotional arousal. Self-regulation is the incorporation of self-management strategies of self-monitoring, self-evaluation, and self-reinforcement employed to control an aspect of behavior over time (Lorig, Hurwicz, Sobel, Hobbs, & Ritter, 2005; Noland, 1989). Self-efficacy beliefs are more important to the adoption phase of a clinical exercise program, whereas self-regulatory skills have more importance in the exercise maintenance phase (Woodard & Berry, 2001). Interventions to promote self-management/self-regulation over time include education for collaborative self-management, self-monitoring skills, self-evaluation, and self-reinforcement. Rejeski et al. (2003) have cited two major limitations to present cardiopulmonary exercise programs that result in limited adherence to exercise over time: (1) programs provide neither the motivation nor instruction and practice to develop self-regulatory skills for behavior change to support adherence and (2) programs assume that desired outcomes such as improved self-efficacy for walking are a direct result of improved physiological functioning alone, without linking of training and practice to outcomes.
Eligible outpatients were randomized to either standard cardiopulmonary rehabilitation or the exercise adherence intervention using a computerized adaptive treatment assignment algorithm (Pocock, 1983) stratified by diagnostic group (HFrEF or COPD), 6-minute walk distance (6MWD) of <600 feet or >600 feet, Charlson comorbidity score of ≤2.0 or >2.0 (Charlson, Pompei, Ales, & MacKenzie, 1987), and driving distance to the outpatient site. The rationale for the randomization scheme was to ensure equal numbers of patients in both intervention groups with differing diagnoses, taking into account baseline physical capacity. The design, outcome measures, and intervention protocol were previously described (Dougherty et al., 2011). The trial was approved by the VA Research and Development and Human Subjects Committees Institutional Review Board at the VA Puget Sound Health Care System, Seattle, WA, and all participants provided written informed consent. An independent data and safety monitoring board provided oversight of the procedures, protocol, and events. The introduction of bias during recruitment was reduced by using scripted screening tools that provided detail and consistency for decision-making regarding subject inclusion or exclusion. Randomization and preprogram (Time 1) measures were carried out prior to beginning the exercise programs. Postprogram measures (Time 2) were completed at the end of the adherence intervention at 6 months by a team member blinded to group assignment.
Setting and Participants
The study was conducted at the VA Puget Sound Health Care System, Seattle, WA, with the adherence intervention taking place in part in the community and home setting. Participants were recruited between 2009 and 2012. Ninety HFrEF or COPD patients were randomized into the study when they met the following criteria: optimally managed, severe COPD (FEV1% predicted < 50%) or HFrEF (ejection fraction [EF] < 40%), one disease-related hospitalization in the past 2 years or at least two unscheduled outpatient visits over the past year related to cardiopulmonary disease, a working phone, and willingness to participate in an outpatient exercise and self-management program. Exclusion criteria were unstable disease or recent surgery that precluded exercise, a supplemental oxygen requirement at rest of >4 L per minute, already exercising three times a week, inability to ambulate, uncontrolled mental illness, alcohol or drug abuse, or a life expectancy of less than 1 year. COPD patients’ level of disease underwent GOLD staging (Global Initiative for COPD, 2011). The rationale for including only patients with severe disease was to determine the ability of cardiopulmonary rehabilitation to halt or stabilize the downward trajectory of the illness condition on functional capacity.
The sample size for the study was based on expected change in the primary outcome of mean difference in total steps per day of 500. This had 80% predicted power for detecting an effect size of 0.45, enrolling 80 patients per group, using a two-tailed p = .05. At the end of the enrollment period, no study participant experienced such a change in the outcome in either group after enrolling more than half of the expected sample size.
The two interventions being compared in this study are based on social cognitive theory, incorporating concepts of self-efficacy and self-regulation. Table 1 provides a detailed comparison of the two intervention programs. The adherence intervention consisted of an outpatient/home-based program of 4-week duration of 4 hours of exercise and integrated self-management education (n = 46). Following the 4-week outpatient phase, a home safety evaluation was completed. Participants were then asked to walk for 30 minutes/3 times/week, record walking sessions and pedometer readings in an exercise log, self-monitor symptoms, and were followed with weekly telephone coaching for 3 months to maintain exercise after the outpatient program. The final 2 months of the self-management intervention included biweekly coaching by phone, recording home walking in exercise logs, and self-monitoring of symptoms. Adherence with the telephone coaching was 62.3%, and minutes walked per week was 78.4±73 minutes (90 minutes expected per week) or 87.1% over this period. Throughout the 5-month home portion, monthly tune-up sessions in which the patient returned to the outpatient setting to exercise on equipment were encouraged. Adherence with the tune-up sessions over this period was 38.3%. Standard outpatient cardiopulmonary rehabilitation consisted of 8-week duration of 2 hours of exercise and self-management instruction (n = 44). Following the 8 weeks of standard cardiopulmonary rehabilitation, patients were given a pedometer to track steps per day and encouraged to walk 30 minutes/3 times/week. Adherence with home walking following standard rehabilitation was not recorded.
Outpatient exercise sessions in both groups began with 5 minutes of upper and lower extremity stretching, followed by the goal of walking on a treadmill for 20 minutes and exercising on the NuStep for 20 minutes at a pace that reached a Borg rating of 4–6 (moderate to strenuous). Five minutes of free arm weights and 5 minutes of arm ergometry followed aerobic exercise. A 5-minute cool-down consisting of upper and lower extremity stretching concluded each session. All outpatient exercise sessions were monitored using blood pressure, telemetry (heart rate and rhythm), and oxygen saturation monitoring. The number of minutes and type of aerobic activity were individually prescribed and were based on the baseline 6MWD as outlined by Probst, Troosters, Pitta, Decramer, and Gosselink (2006). The beginning treadmill walking speed was derived by dividing the distance walked by time (6 minutes). Exercise was advanced based on tolerance (Borg rating 4–6), with a goal of walking at 60% of the initial workload for treadmill exercise. The number of metabolic equivalents (METs) achieved in treadmill walking and using the Nu-Step were added together for each session and summed over the program in both groups. The average change in MET levels from the first to the final session was similar between groups (p = .67), despite the standard cardiopulmonary (CP) rehabilitation group exercising for 4 weeks longer than the adherence group. The total volume of exercise performed in the 4-week program versus the 8-week program was significantly higher in the 8-week standard program, 632.5 versus 1,026.7 MET minutes, F = 17.93, p = .002.
As shown in Figure 1, 37 of 46 (80%) assigned to the adherence intervention completed 80% or more of the required outpatient sessions, whereas 25 of 44 (57%) of those in standard CP rehabilitation completed at least 80% or more of outpatient sessions. Intervention fidelity was carefully monitored throughout the study by attendance and participation in the outpatient sessions. In the 5-month portion of the adherence intervention, home walking and recording steps/log and symptoms were monitored in telephone calls by study personnel. Participation in outpatient tune-up sessions was monitored by attendance and participation. At the completion of the 8-week standard CP rehabilitation program, home walking was encouraged but was not monitored during the follow-up period. At the 6-month follow-up (Time 2), 89.1% of those in the adherence intervention and 86.3% of those in the standard CP rehabilitation completed all outcome measures.
The primary outcome was functional capacity at 6 months measured using two methods: (1) 6MWD in meters—best of two walks (Bean et al., 2002; Cavanaugh, Coleman, Gaines, Laing, & Morey, 2007; Steele, 1996) and (2) daily activity measured using the Stepwatch Activity Monitor (SAM; Orthocare Innovations, LLC, Mountlake Terrace, WA), a pager-sized device worn above the dominant ankle that records stride cycles. Participants wore the SAM for a minimum of 10 hours for a least five consecutive days, including both weekdays and week-end days. The SAM records the following in 1-minute epochs: (1) total steps taken per day (stride counts doubled), (2) peak performance (short walking bursts obtained by ranking all minutes of the day and averaging the highest 30 values), and (3) percent time spent ambulating at low intensity (0–30 steps per minute; Cheung, Gray, & Karunanithi, 2011; Haeuber, Shaughnessy, Forrester, Coleman, & Macko, 2004; Nguyen, Burr, Gill, & Coleman, 2011). Secondary outcomes were (1) symptoms of dyspnea (Clinical COPD Questionnaire; Kon et al., 2014; van der Molen et al., 2003), depressed mood (Geriatric Depression Scale; Watson & Pignone, 2003), general health-related quality of life (SF-36V; Boueri, Bucher-Bartelson, Glenn, & Make, 2001; Kazis et al., 1998; Sprenkle, Niewoehner, Nelson, & Nichol, 2004), and cardiopulmonary function (brain natriuretic peptide [BNP; Dao et al., 2001; Jourdain et al., 2003] and FEV1% [forced expiratory volume in 1 second % predicted-COPD; Miller et al., 2005]). Measures were taken at (1) baseline study entry (Time 1) and (2) 6 months later at the conclusion of the adherence intervention (Time 2).
The analysis was carried out on the total sample (N = 90) using an intent to treat strategy. Student’s t tests and chi-square analysis were used to evaluate baseline group equivalence with respect to outcomes and background variables. Outcome variables in both the total sample and the subsets of COPD or HF were analyzed using a repeated-measures ANOVA with Time × Group interaction, controlling for baseline age, body mass index, current smoking, driving distance from the VA, and Charlson score. Statistical significance was defined as a two-tailed alpha level of < .05. SPSS version 19.0 (SPSS, Inc., Chicago, IL) was used for the analysis.
Over a 4-year period, 673 potential subjects were screened, 272 of whom chose not to participate and 311 did not meet inclusion/exclusion criteria or contact could not be established. Although we screened a much larger number of patients with HFrEF (391) compared to those with COPD (282), many fewer with HFrEF were randomized to the study (27 HFrEF compared to 63 COPD) because of lack of interest or difficulties with walking. Program attrition was approximately 20% from the adherence intervention group and 44% from the standard care program. These findings are consistent with earlier findings for pulmonary rehabilitation in our research program (Steele et al., 2000, 2008; see Figure 1).
There were no significant differences on baseline measures of age, body mass index, oxygen use, smoking employment/disability, comorbidities, level of obstructive lung disease, or 6MWD between the adherence intervention and standard care groups. In the total sample, HFrEF subjects were slightly younger than those with COPD (63 years compared to 67 years), had higher baseline 6MWD-meters (390 ± 116 vs. 339 ± 117), and were less likely to be disabled (48%) or unemployed (41%). Likewise, COPD patients were more likely to use oxygen at least 8 hours per day and experienced greater levels of dyspnea. Although not significant, HFrEF subjects in the standard care group had higher average BNP levels (3,171 vs. 1,930) and lower 6MWD (372 m vs. 409 m) compared to the HFrEF subjects in the adherence intervention. There were no women recruited into the sample based on the study site serving primarily U.S. veterans (see Table 2).
COPD subjects had substantially higher levels of obstructive pulmonary disease compared to our previous work (FEV1% predicted mean of 32% compared to previous means of 38%–42%) and to that of others (Marín Royo et al., 2011; Pitta et al., 2008; Steele et al., 2000, 2008). Whereas, HFrEF participants had similar levels of (EF%) compared to other studies (Carvalho, Garrod, Bocchi, Pitta, & Guimaraes, 2010; Evans et al., 2010). There were no overall differences in FEV1% predicted, but 97% of the standard care group had Stage III or IV (severe or very severe) disease (Global Initiative for COPD, 2011) compared to 84% in the adherence group.
Intervention Group Outcomes
In the total sample (N = 90) at the end of 6 months, there were no significant differences between the two interventions with respect to the primary outcomes of 6MWD or total steps per day. Secondarily, symptoms of dyspnea, depression, quality of life, and cardiopulmonary function were not statistically different between the groups (Table 3). Both groups demonstrated a decline in 6MWD at 6 months despite participating in two different rehabilitation programs. As well, there were noted declines in total steps per day and increases in time spent inactive at the 6-month follow-up.
When determining benefits on the primary outcomes by adherence groups (<80% or ≥80%), there was no statistically significant improvement from baseline to 6 months on total steps per day, peak performance, or 6MWD for either group. However, those who were adherent at the ≥80% level experienced gains in these outcomes. There were noted statistically significant improvements between those that were adherent compared to nonadherent on percent time inactive, such that those in the ≥80% adherent group in the adherence intervention experienced significant reductions whereas those in the standard rehabilitation program experienced an increase in percent time inactive (Wald X2 = 4.94, p = .03). In addition, in both HFrEF and COPD groups who were nonadherent, there was an increase in percent time inactive at 6 months, whereas the adherent HFrEF group, but not the adherent COPD group, experienced a significant reduction in percent time inactive (Wald X2 = 6.17, p = .01).
COPD versus HFrEF Outcomes
Patients with HFrEF and COPD demonstrated no significant differences between treatment groups in any of the outcomes. Table 4 outlines the primary study outcomes comparing the intervention groups by diagnosis. Although not significant, HFrEF patients had slight improvements in 6MWD at 6 months in both intervention groups over COPD. In contrast, both intervention groups in those with COPD had noted reductions in 6MWD below pretreatment levels. BNP, an index of HF severity, was reduced in both treatment groups of HFrEF subjects, possibly reflecting improved medical management or that the exercise performed was not detrimental to left ventricular function. FEV1% predicted, an index of obstructive disease, improved in the standard care group, but not in the adherence intervention, although not significantly. There were no significant differences in dyspnea, depression, or quality of life by intervention or diagnostic group.
To our knowledge, no clinical trials comparing differing cardiopulmonary rehabilitation interventions in HF and COPD have been carried out, even though the constellation of life-altering symptoms, frequent exacerbations, and activity limitations are very similar in both of these groups.
Comparison of Intervention Effects
We found no significant differences between standard cardiopulmonary rehabilitation and the adherence intervention on primary or secondary outcomes. Although this might be expected in the intent to treat sample that included adherent and nonadherent participants, these null findings were also evident when examining the differences between those with HFrEF and those with COPD. There were a larger number of participants with COPD in the study, most of whom had severe disease with at least 84% classified as GOLD III and IV (Evans et al., 2010; Pitta et al., 2008; Steele et al., 2000, 2008). Patients with severe and very severe COPD experience more frequent COPD exacerbations and have poorer functional outcomes after pulmonary rehabilitation (Global Initiative for COPD, 2011; Man et al., 2015), findings consistent with our previous work (Steele et al., 2010). Nonetheless, the results reflecting no difference between the longer, adherence-focused intervention and standard care contrasts with the work of Pitta and colleagues (2008). These authors noted that, although significant improvement in functional performance occurred after 3 months of pulmonary rehabilitation, only after 6 months of an exercise program was there improvement noted in daily activity. Although our adherence intervention program was 6 months in length, the final 5 months was composed of home walking with phone coaching, which was less intensive compared to the twice-weekly supervised outpatient exercise characterizing the Pitta program. In addition, attrition in our study from the standard care group was higher (44%) compared to the adherence intervention group (20%), presumably due to the demands of a longer program. Though severely ill, both HFrEF and COPD patients tolerated both outpatient and home-based components of the program without ill effects, suggesting that this strategy is both feasible and efficient.
The preponderance of recent research addressing activity adherence strategies in pulmonary rehabilitation have shown minimal or inconsistent benefit (Burtin et al., 2015; Wilson, O'Neill, Collins, & Bradley, 2015), in keeping with our findings. Unexpectedly, however, functional capacity was not improved for either intervention group, although 6MWD has consistently shown significant gains in both HF and COPD following cardiopulmonary rehabilitation programs (Evans, 2011; Pitta et al., 2008; Steele et al., 2008). One possible reason is that the points of postprogram measurement were 4–5 months removed from the respective outpatient exercise component of each intervention, possibly reflecting long-term decline after supervised exercise (Ries, Kaplan, Myers, & Prewitt, 2003; Steele et al., 2008). The steeper trajectory of declining health in the relatively large numbers of patients with GOLD III and especially GOLD IV COPD may have further blunted intervention benefits in both groups (Albuquerque, Quaranta, Chakrabarti, Aliverti, & Calverley, 2016; Niewoehner, 2006).
The benefits of CP rehabilitation in severe and very severe cardiopulmonary illness have not been systematically investigated. A recent systematic review of high-intensity pulmonary rehabilitation found improvements in tidal volume and inspiratory capacity in severe COPD (FEV1 40–50% predicted), whereas other respiratory parameters were not improved or declined (Osterling, MacFadyen, Gilbert, & Dechman, 2014). Ringbaek, Brondum, Martinez, Thogersen, and Lange (2010) noted small improvements in the shuttle walk test after CP rehabilitation in severe COPD (FEV1 36% predicted) that was not sustained up to 12 months. Similarly, Albuquerque et al. (2016) found 6MWD improvement to be less in those with severe COPD with hyperinflation. In a meta-analysis of CP rehabilitation in more severe HF (EF% = 28%; van Tol, Huijsmans, Kroon, Schothors, & Kwakkel, 2006), there were noted improvements in 6MWD of 151 feet or an increase of 11% from baseline. More recent results of the HF action trial (O’Connor et al., 2009) in participants with mean EF% = 24.6%, showed improvements after the 12-week cardiac rehabilitation outpatient intervention of 65 feet, with a reduction in 6MWD noted at 12 months to 42 feet. Smaller improvements of 4% or 30 feet in our HFrEF sample occurred. These investigations demonstrated that improvements in functional capacity in those participating in CP rehabilitation with more severe COPD or HF are modest to small.
Comparison of HFrEF versus COPD Effects
No differences were evident in daily activity in HFrEF and COPD subjects. HFrEF subjects tended to be younger with slightly higher functional capacity than COPD patients at baseline. Their 6MWD improved at Time 2 following both interventions, whereas this remained unchanged or declined in COPD group. Although the HFrEF participants in standard care had higher (but nonsignificant) levels of disease at baseline compared to those in the adherence intervention, there was an almost equal lack of decline in functional status evident at Time 2. Dyspnea was also greater at baseline for COPD subjects, but both COPD and HFrEF participants showed a decline in dyspnea at Time 2, although these changes were not significant. Mood changes were not significant in either group.
The outcomes for HFrEF subjects in our study are consistent with those of Evans and associates (2010), who demonstrated significant improvement in functional capacity measured by shuttle walk tests after standard pulmonary rehabilitation in HF subjects. The HF subjects in both studies had similar cardiac function with mean EF% = 30–31%, and both HF groups demonstrated improvement following the standard pulmonary rehabilitation program. In contrast, the Evans COPD group had less severe COPD compared to subjects in the present study (FEV1% of 42% compared to 32%). The Evans COPD subjects improved significantly on all functional capacity, symptom, and life quality outcomes compared to COPD subjects in our current study, who showed no significant change following either intervention.
Little is known about the natural history of functional decline in cardiopulmonary illness, particularly in late disease where even minor exacerbations and subtle lifestyle changes affecting activity may contribute to premature frailty and decreased health status (Marín Royo et al., 2011; Niewoehner, 2006). On the basis of 3 years of study of severely ill COPD patients, Kapella, Larson, Covey, and Alex (2011) estimated that daily activity declined 3% annually and probably underestimated the rate of decline in more severe illness. The present study suggests that, in both intervention arms, functional capacity declined at a similar rate (3%) in this sample of more severe disease groups, despite achieving a significant increase in workload in both rehabilitation programs. As exercise-based interventions continue to be developed for persons with severe cardiopulmonary illness, a threshold for not enrolling those in rehabilitation with more severe disease may be more clearly defined. By refining evidence-based exclusion criteria for such expensive and work-intensive programs, greater efficiency should result as well as a reduction in physical and emotional stress in patients with limited improvement potential.
The sample was composed of men; therefore, the findings should be generalized to women with caution. Likewise, the SAM might inadequately represent upper extremity activity, although Walker et al. determined that lower extremity monitors adequately represented total energy expenditure in COPD patients (Walker, Burnett, Flavahan, & Calverley, 2008). Without a no-treatment control group, there was no way to estimate illness-related decline in daily activity, functional status, and other variables of interest for comparison with the interventions. Finally, inferences about the HFrEF group might be less reliable because of the small number of subjects in this treatment group.
Findings from this clinical trial add to knowledge about the efficacy of interventions in late-stage cardiopulmonary disease. As current treatment prolongs the natural history of heart and lung disease, such a focus is timely. Our research suggests that, following both traditional outpatient and more long-term programs that involve phone coaching, a trajectory of declining function is evident in the absence of continued supervised exercise, most notably in end-stage COPD patients who may be at a steeper decline in their trajectory of illness. Interventions that combine severely ill COPD and HFrEF patients are nonetheless feasible and have equivalent short-term benefits for maintaining functional status. Future research should address the impact of exercise interventions on the trajectory of decline in severe, end-stage illness with stabilization of function rather than improvement in cardiopulmonary function, as a worthy goal of treatment.
Key Practice Points
- Cardiopulmonary rehabilitation that includes both severely ill patients with either COPD and HFrEF is feasible to complete.
- Cardiopulmonary rehabilitation that is completed partially at home provided no additional benefit compared to standard outpatient rehabilitation.
- Outpatient cardiopulmonary rehabilitation with follow-up over 5 months in late-stage disease, in either COPD or HFrEF, did not improve cardiopulmonary function.
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