INTRODUCTION AND PURPOSE
Congenital heart disease (CHD) occurs in 1% of all live births.1 There are more than 120 000 adolescents living with CHD in the United States.2 Depending on the nature of their defects, adolescents with CHD often have impaired functional health status3 , 4 and quality of life (QoL).5 Exercise training is safe for adolescents with CHD, improving functional capacity and muscle strength,6 , 7 leading to improved QoL.8 , 9
Clinical practice guidelines for adolescents with CHD include recommendations for physical activity (PA), at levels that are appropriate for the most common cardiac defects.10 It is recommended that adolescents with CHD be physically active to a similar degree as the general population.10 , 11 The majority of adolescents with CHD are recommended to accumulate 60 minutes of moderate-to-vigorous PA (MVPA) daily.12
Despite these clinical recommendations,10 reports indicate that adolescents with CHD do not engage in sufficient PA.13–16 In some cases, degree of PA among patients with CHD is lower than that of peers.13 Limited PA in adolescents with CHD may be attributed to parental overprotection, and lack of, or inconsistent, activity advice from health care providers.17 , 18 This could result in patient uncertainty regarding safe and appropriate activities, and ultimately lead to activity avoidance and sedentariness.
Interventions to improve PA in this population include pediatric cardiac rehabilitation.7 However, these programs are not widely available, and barriers to participation in such supervised programs including transportation, distance, and time can be insurmountable in adolescents with CHD. One approach to behavior change, which does not need to be delivered face-to-face, is motivational interviewing (MI).19 MI takes a nonjudgmental, patient-centered approach to evoke, not impose, motivation aimed at resolving ambivalence. A meta-analysis of MI interventions targeting PA showed benefits with modest effect sizes.20 There has been only one study that used MI to promote PA in adolescents with CHD16; however, it offered only one MI session in conjunction with a structured exercise program. There were significant increases in MVPA with intervention in the intervention group.
Considering the context of CHD in adolescence, published systematic reviews of exercise training interventions and PA guidelines for the CHD population,6 , 7 , 10 , 17 an adapted MI intervention delivered by telephone was developed to promote MVPA. The objectives of this pilot trial were to evaluate: (1) the implementation and acceptability of this adapted MI intervention (ie, adolescent adherence to sessions, effect on intended change mechanisms of self-efficacy, and stage of change) and (2) whether a new intervention has the capacity of being successful to improve PA, physical fitness, and QoL in a controlled setting.21
Design, Setting, and Procedure
This was a pilot randomized controlled trial21 , 22 of an adapted MI intervention. It was a 12-week trial, with 2 parallel groups (intervention and comparison). The research ethics board for Toronto's Hospital for Sick Children approved this study (number 1000040503). Parental assent was not required.
The outpatient pediatric cardiology clinic list was screened 1 month prior to upcoming patient appointments between March 2013 and March 2015. Eligible adolescents with CHD were mailed information about the study. Patients were asked to call the study coordinator if they had any questions or if they were interested in participating. An opt-out card was available to send back for those who chose to decline participation.
A study coordinator met with patients who did not respond or expressed interest in participating at their scheduled clinical appointments, at which time they were given information about the study and questions were answered. Informed consent forms were reviewed, and those agreeing to participate signed. An on-site pretest assessment was then scheduled for a later date.
Randomization and Blinding
Participants were randomly allocated to the intervention or comparison group. An external investigator generated the random allocation sequence, and one of the investigators enrolled and assigned participants to the intervention. A random number generator was used to create blocks of 2 or 4, to achieve 1:1 group randomization within each block. Assignment was concealed by sealing of tamper-proof, consecutively numbered envelopes by a researcher remote from the investigators and participants. Participants were assigned the next envelope in sequence.
Participants could not be blinded to group assignment. Study personnel were not blinded to group assignment, with the exception of the exercise physiologist who prepared the individual exercise intervention.
Adolescents (13-17 years of age) with prior surgical repair of CHD of any type were eligible to participate. Adolescents who were less than 1 year after open heart surgery, who had exercise contraindication/limitations as identified by the responsible cardiologist (ie, history of arrhythmias, syncope, hypoxia, and pulmonary hypertension), significant cognitive disorders that would hinder the completion of questionnaires and full participation in the MI sessions, or other medical conditions that could influence PA participation were excluded. Because this was a pilot trial,22 there was no power calculation to determine required sample size to detect a significant difference in the outcomes by group. Hence, only limited efficacy is tested,21 to inform potential future sample size calculations for a larger trial.
Comparison—Individualized Exercise Program
A Canadian Society of Exercise Physiology-certified exercise physiologist prepared a 12-week, individualized exercise intervention for each participant determined by baseline physical fitness (see assessments later), self-reported current activity participation, and information provided by the participant that could impact exercise intervention, for example, sport participation, work schedule, or religious commitments. The intervention progressively increased in frequency, intensity, and duration toward guideline-based PA recommendations for adolescents (60 minutes of daily MVPA).23 Consideration was given to the participant's built environment, previous exercise experience, exercise interests, and personal schedule. A sample exercise intervention for a participant is available as Supplemental Digital Content 1 (available at: http://links.lww.com/PPT/A218).
Participants received 1 telephone call after 4 weeks and 1 telephone call after 8 weeks by the exercise physiologist to evaluate the need for modification to the intervention. Participants allocated to the comparison group did not receive additional contact beyond these calls.
Intervention: Adapted Motivational Interviewing
In addition to receiving an individualized exercise intervention, participants allocated to the intervention group also participated in adapted MI sessions to explore and resolve ambivalence regarding PA. The intervention was designed to focus on behavior and intrinsic motivation, to be collaborative in delivery, and was aimed at advancing stages of change24 and increasing exercise self-efficacy. Key MI principles were used during each session as appropriate, including autonomy, empathy, reflective listening, summaries, and open-ended questions.25 The intervention took into consideration participants’ life stage as an adolescent, and their growing independence and hence requirement for self-management skills.
The intervention consisted of biweekly sessions by telephone over the 3-month period (ie, 6 sessions). The first session aimed to build rapport with the participant, understand their current views about exercise and self-reported activity level. The importance of PA in their life and their perceived confidence to change behavior were assessed, and advantages and disadvantages of making a change were explored. Subsequent sessions built upon the previous session(s) with progression toward building a reasonable plan with the participant that would increase their MVPA. Where appropriate and with their permission, information or suggestions were provided to participants regarding exercise techniques based on their progress with the exercise intervention. An outline of the adapted MI sessions is available as Supplemental Digital Content 2 (available at: http://links.lww.com/PPT/A219).
One investigator received training from the MI Network of Trainers during a 2-weekend training course. Supervised practice sessions were completed following the training course, where individualized feedback was provided from MI trainers and peers.
Sociodemographic and clinical characteristics of participants were extracted from medical charts. First, to test the implementation and acceptability of the intervention, the number of completed sessions and the duration of each session were recorded.
To test whether the intervention had the intended mechanistic effect, stage of change and self-efficacy were assessed in all participants at pre- and posttest via self-report survey. The Readiness to Change questionnaire26 is a 4-item survey that was administered to assess the participant's motivation to change PA. It has been validated in a pediatric sample.27 Scores range from 0 to 4, with each value representing the following stages, respectively: precontemplation, contemplation, preparation, action, and maintenance. The Self-Efficacy Scale for Physical Activity28 , 29 was administered. This scale consists of 9 items with total scores ranging from 0-90, with higher scores denoting greater self-efficacy. It has been administered in children20 and adolescents29 with CHD with good psychometric performance.
Participants were invited to complete the following outcome assessments at baseline and during their posttest visit: PA, physical fitness indicators, and QoL. These were to test limited efficacy,21 to support the decision whether to proceed to a full-scale trial and, if yes, potential sample and effect size estimation.
Participants were provided an Actigraph wGT3X-Plus Triaxial Activity Monitor (Actilife, Pensacola, Florida). It is a valid and reliable measure of treadmill walking at known speed and an audible shaker.30 The accelerometer was to be worn over the right hip during waking hours for 7 days (2 weekend days and 5 weekdays), except when bathing or swimming. Participants were provided with a logbook to record the dates and times they wore the monitor to substantiate data where ambiguous.
Accelerometer data were included where a minimum of 3 valid (ie, minimum wear time of 10 hours/day) days of data was received. PA intensity was categorized using cut-point conventions by Evenson and colleagues.30 (sedentary = 0-100 counts per minute [cpm]; light = 101-2295 cpm; moderate = 2296-4011 cpm; vigorous = ≥4012 cpm). Minutes per day were averaged at each intensity, and the mean minutes of MVPA per day computed. The primary end point was changed in MVPA from pre- to posttest.
Physical Fitness Indicators
Anthropometric measures included standing height and body weight (to compute body mass index [BMI]; BMI = kg/m2), as well as waist circumference (average of 2 measurements taken at the narrowest point above the iliac crest).31 Aerobic fitness was assessed using the validated Modified Canadian Aerobic Fitness Test.32 , 33 Participants were asked to take alternating steps to a set cadence from an audio cue to estimate oxygen consumption; flexibility (sit and reach), muscular strength (grip strength), and muscular endurance (partial curl-up) were also assessed using standard protocols.33 This collection of tests was selected as it has been previously administered in a representative sample of adolescents as part of the Canadian Health Measures Survey.34 These data were used as a comparator to interpret the results in this study.
Global and health-related QoL were assessed via self-reported surveys. A visual analog scale was administered to assess global QoL. The anchors were 0 to represent “worst possible QoL” and continued to a value of 100 to represent “best possible QoL.”35 Dimensions of health-related QoL were assessed using the 23-item Pediatric QoL Inventory (PedsQL) Teen (13-18) Report.36 Scores for items in each of 4 domains (physical, emotional, social, and school; range 0-100 for each) were used to calculate total health-related QoL, with higher scores denoting greater QoL.
All statistical analyses were performed using SAS version 9.4 (SAS Statistical Software, Cary, North Carolina). To compare pretest characteristics between the MI and comparison participants to verify equivalence between groups through the randomization, the Fishers exact test for all categorical variables, t tests assuming unequal variance between samples for continuous variables (Satterthwaite methods) were used. Second, differences between participants who were retained versus lost to follow-up were tested using t tests or χ2, as applicable. A similar approach was used to test the differences in participant characteristics between those who had valid accelerometer data at both time points versus those who did not.
Q-Q plots were examined to assess whether the outcome variables were normally distributed. To test the first objective (intervention implementation/acceptability and change mechanism), the mean number of sessions in which the intervention group participated and duration was computed. Change in self-efficacy and stage of change scores from pre- to posttest were tested in the intervention group using the paired t test (or Wilcoxon rank sum if not normally distributed) and χ2, respectively.
Changes in outcomes (PA, fitness, and QoL) were analyzed using paired t tests (or Wilcoxon rank sum if not normally distributed) within the group. Change scores were computed, and differences in each by group were analyzed using independent samples t tests. Given the number of outcomes assessed, a Bonferroni correction was applied, with a P level of < .006 considered statistically significant.
Participant flow through the trial is shown in Figure 1. Characteristics of randomized participants at baseline are shown in Table 1. There were no differences observed by group, suggesting successful randomization. The mean BMI was in the normal range (18.50-24.99).31 There were no differences between participants who were retained and those who were lost to follow-up by age (t = −0.43, P = .67), sex (χ2 = 0.70, P = .58), or CHD severity (χ2 = 0.35, P = .58).
The number of participants with valid accelerometer data at each assessment point is shown in Figure 1. There were 11 (61.1%) participants in the intervention group and 12 (66.67%) participants in the comparison group who had valid accelerometer data at both time points for analysis. There was no difference in age (P = .59) or CHD severity (P = .12) among participants with valid accelerometer data and those without or with invalid data; however, significantly more females than males had invalid accelerometer data (χ2 = 5.46, P = .04).
Intervention Implementation/Acceptability and Change Mechanism
Of the 6 planned sessions, intervention participants completed a mean of 4.20 ± 1.20 sessions. The average duration of the MI sessions was 15.21 ± 4.30 minutes. As shown in Figures 1 and 2, 11.2% dropped out of the intervention, most often citing lack of time.
During MI sessions, participants identified challenges in meeting PA recommendations or goals discussed. Reasons often included personal factors such as spending time with friends or academic priorities (eg, assignments and examinations). Table 2 includes PA self-efficacy and stage of change by time and group. Self-efficacy and stage of change did not differ between groups at pretest (Wilcoxon rank sum P = .78; and χ2 = 1.72; P = .66, respectively). Overall, participants reported moderate confidence in being physically active, and most reported being in the maintenance stage at both time points.
There was no significant change observed in the intervention group from pre- to posttest in self-efficacy (t = 0.41; P = .69) or stage category (χ2 = 5.81; 0.27; comparison P also nonsignificant). This does not confirm our hypothesis that the MI intervention would promote greater self-efficacy and advancement through the stages of change.
Outcomes: Limited Efficacy
Figure 2 displays mean MVPA/week by group and time, with mean minutes of PA per day reported in Table 3 by intensity level. PA was not normally distributed, and hence Wilcoxon rank sum tests were used. At pretest, there were no significant differences between groups for time spent in sedentary (P = .75), light (P = .35), moderate (P = .21), vigorous (P = .75), or moderate-to-vigorous (P = .32) intensity PA, as expected.
The mean MVPA at baseline was 47.24 ± 16.36 minutes per day, corresponding to 78.7% of the daily-recommended amount. Six of 24 (25.0%) participants met the 60-minute MVPA recommendation, with the highest value being 77 minutes of MVPA per day obtained at pretest for 1 participant. Participants with mild CHD accumulated more MVPA per day than participants with moderate-to-severe CHD at baseline (54.32 ± 15.23 vs 40.21 ± 14.77 min/d, respectively; P = .03). Females accumulated significantly less MVPA per day than males at baseline (34.70 ± 8.49 vs 53.55 ± 15.80 min/d, respectively; P < .001).
As shown in Table 3, there were no statistically significant changes in MVPA (or in activity of any intensity) from pre- to posttest within either group, and changes would not be considered clinically meaningful. There was no significant difference in change in MVPA between groups (comparison: 8.40 ± 23.54; intervention: −13.02 ± 17.37; t = 2.11; P = .05; r = −0.11). This does not support our hypothesis, and while not significant there was a trend toward lower MVPA with the intervention (likely driven by the trend toward lower vigorous-intensity activity).
Physical fitness indicators are reported in Table 3. Overall, 8 (22.2%) participants were considered overweight or obese (ie, BMI >25) at pretest. With regard to abdominal girth, 4 males (11.1%) were considered at increased or high health risk (ie, >94 cm) and 1 (2.8%) female was considered at increased health risk (ie, >80 cm).31 Predicted O2 consumption was low (28.09 mL/kg/min) when compared with national values for Canadian adolescents without CHD (11-14 years: 51.6 mL/kg/min; 15-19 years: 46.5 mL/kg/min).36 BMI, waist circumference, flexibility, and grip strength values were comparable to peer adolescents.33
There was no difference at pretest between groups for any fitness indicator. As shown in Table 3, there were no significant changes in any physical fitness indicator from pre- to posttest in either group. Furthermore, there were no differences between groups for change in waist circumference (t = −0.29; P = .77), BMI (t = 0.53; P = .60), vertical jump (t = 0.71; P = .48), oxygen consumption (t = 0.38; P = .71), handgrip (t = 0.59; P = .56), sit-and-reach (t = 1.25; P = .23), or partial curl-up (t = 0.58; P = .57).
Participants reported overall positive psychosocial outcomes at baseline. There were no significant differences at pretest between groups in global (t = −0.32; P = .75) or health-related QoL (t = −0.30, P = .76). There were no significant changes in QoL domains from pre- to posttest in either group (Table 3). Furthermore, there were no differences for global QoL (t = 0.57; P = .58) or total health-related QoL (t = 0.47; P = .64).
It is well-established that PA is associated with improved functional status and positive psychosocial outcomes in adolescents37 and those with CHD,9 although some mixed findings are reported.38 This study tested the acceptability, implementation, and limited efficacy of a theory-based intervention to improve MVPA in adolescents with CHD. The intervention was fairly well received, with only a 10% dropout and 70% adherence to sessions. While not powered to observe an effect on outcomes, results did not support the intervention. However, this study is one of few that assessed functional fitness among other objective indicators in adolescents with CHD. The MVPA and physical fitness of patients in this study were comparable to those of healthy peers,34 except functional capacity was quite low and one-quarter of participants were overweight or obese.
While the sample size for this pilot study was small, the adapted MI intervention had no discernible effect on stage of change or self-efficacy for PA as intended, and hence not surprisingly had no effect on outcomes (and in fact may have tended to have a negative effect on vigorous-intensity PA). The lack of effect of this intervention could be attributed to several factors, including the high degree of PA and exercise self-efficacy at baseline and that most participants were in the maintenance phase (ie, selection bias), the adaptation of MI, intervention delivery via telephone rather than in-person, or characteristics of the sole counselor. Patients may have not considered the intervention to be important, as they engaged PA levels similar to healthy peers at baseline,36 which was almost 80% of recommended levels.12 Finally, the provision of an exercise intervention and 2 calls with the exercise physiologist in the comparison group may have diminished any intervention effect; the intervention itself as delivered was a total of 60 minutes only over and above these 2 calls (4/6 [67%] planned calls at 15 minutes each on average). The optimal intervention approach (ie, method of delivery and number of sessions) for inactive adolescents with CHD remains unknown and should be explored in future studies.
The average minutes of MVPA per day of patients with CHD in this study was comparable to published values of healthy children (53 minutes of MVPA for males and 47 minutes of MVPA for females aged 15-19 years).34 While the sample in this study may have been more active than the average adolescent with CHD, as they were interested in an exercise study, these results corroborate that adolescents with CHD may not be less active than their healthy peers.13 Voss and colleagues39 assessed PA via accelerometry among patients with various CHD defects (n = 90, 8-19 years old) and comparably reported 42.6 minutes of MVPA per day. In a study conducted by McCrindle and colleagues15 of patients (n = 108; 7-18 years old) with complex CHD, 38% of patients met current PA recommendations. However, it was curious that although MVPA and other fitness indicators were consistent with healthy peers, functional capacity was much lower. It should be tested whether this finding is robust, and if so future research is needed regarding the effectiveness and mode of the PA in which adolescents with CHD engage.
Patients in this study accumulated relatively similar sedentary minutes as their healthy peers (590 min/d vs 554 min/d).34 This sedentary behavior, representing approximately 74% of their time, was also similar to that reported in patients with CHD (70%).39
This study demonstrated favorable psychosocial health among adolescents with CHD. Patients were confident they could be physically active and reported relatively high QoL. The high proportion of patients with simple CHD may have contributed to the high values, and collectively contribute to the high PA participation observed in our study.
Pediatric cardiac rehabilitation should continue to serve as an important venue to promote PA in children and adolescents with CHD. The beneficial effects of these programs on exercise capacity, psychosocial outcomes, and PA have been reviewed previously.7 Serious adverse events have not been reported. Perhaps by intervening earlier in this population and over a longer period, with those who have lower PA and self-efficacy, lifelong PA habits can be ingrained, resulting in better physical and psychosocial outcomes. Unfortunately, there are few such programs available; broader delivery could be achieved by offering home-based services as is available in adult programs.40 This could also address some of the barriers to adhering to the intervention and MVPA reported by participants in this study.
Physical therapists are well-positioned to deliver pediatric cardiac rehabilitation programs, as well as provide exercise and behavior change interventions, given their in-depth understanding of chronic conditions like CHD. Furthermore, community-based physical therapists may be integral to support home-based programs and delivery of behavioral interventions like MI for patients with CHD where they cannot readily access a center.
Caution is warranted when interpreting these results. First with regard to generalizability, this study was limited to a single institution. Also related to generalizability limits, is that the sample was an active group already in the “maintenance” stage. Due to this selection bias, it is warranted that the intervention is tested in an adequately powered inactive cohort before conclusions on efficacy are drawn.
Second and related, given this was a pilot study, the sample was small and the lack of intervention effect could be due to low power. The sample size was also reduced due to low retention. This may have introduced bias, particularly considering there were fewer females with valid accelerometer data than males.
Third, with regard to design, the outcome assessor was not blind to condition, and this may have biased the results. Fourth, with regard to analysis, they were not undertaken on the basis of intention to treat. However, with regard to limitations 3 and 4, given the lack of demonstrated intervention effect, these are not a major concern.
This pilot study suggests that adapted MI was acceptable to adolescents with CHD, given the low 10% dropout rate and 70% adherence to sessions. However, whether it is an effective approach to improving PA among adolescents with CHD cannot be known, due to the nature (ie, those who are physically active, confident in their activity, and have good QoL) and size of the sample. Despite engaging in a fair degree of MVPA (∼80% of guideline-recommended levels), patients nevertheless had reduced functional capacity and one-quarter were overweight or obese.
We would like to acknowledge Caroline Chessex, MD; Rachel Wald, PhD; Erwin Oechslin, MD; Jennifer Russell, MD; and Greg D. Wells, PhD, for early input in the conception of this work.
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