Rodriguez-Escudero, Juan P. MD; Somers, Virend K. MD, PhD; Heath, Amy L. BS; Thomas, Randal J. MD, MSc; Squires, Ray W. PhD; Sochor, Ondrej MD, PhD; Lopez-Jimenez, Francisco MD, MSc
Metabolic syndrome (MetS) is a cluster of risk factors comprising 3 or more metabolic components, including high blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol, impaired fasting glucose, and central obesity.1,2 The prevalence of MetS in the United States is approximately 34% among adults and 50% to 60% in the population older than 60 years, constituting a growing public health problem.3,4 Metabolic syndrome has been strongly associated with increased cardiovascular risk and incidence of diabetes, as well as linked to gastrointestinal tract and respiratory problems and certain types of cancer.5
Lifestyle modification is considered the first line of treatment to reduce most components of MetS.6,7 Modifications focused on increasing physical activity and improving nutritional balance play a sizable role in reducing weight and various MetS components.8 Unfortunately, attempts to modify lifestyle are commonly unsuccessful because of low patient compliance, and to be effective, lifestyle modifications usually require multidisciplinary interventions and extensive resources. Consequently, there is an emerging need for effective medically supervised programs designed to help patients with or at risk for MetS. Ideally, these programs would be established within the resources and facilities of medical programs already targeting lifestyle changes. We describe our experience creating a 6-week cardiometabolic program (CMP) using the resources already available in a cardiac rehabilitation (CR) setting for patients with or at risk for MetS and report the comparative effectiveness of such a program by using 2 different control groups.
We conducted a retrospective analysis of 314 outpatients older than 18 years, who met the inclusion criteria of either obesity (body mass index, ≥30 kg/m2) or impaired fasting glucose (glucose, >100 mg/dL) while attending a cardiovascular health clinic from January 1, 2006, through April 7, 2011. All the eligible patients were asked to participate voluntarily in a self-pay 6-week CMP using the facilities and resources of a CR setting. We also enrolled 2 control groups selected from patients who had signed up for the CMP but either never attended or dropped out at any point after starting the program (control 1) and those who had not signed up for the CMP but had been seen in the outpatient preventive cardiology practice (control 2). We compared changes in components of the MetS from baseline to 6 weeks (for the CMP group) and at 6 months for all 3 groups. We excluded patients who had not given authorization for use of their medical records for research purposes. We also did not include patients with recent history of coronary heart disease. The institutional review board approved this study protocol. All authors have read and approved of the manuscript.
The CMP was conducted in a CR area. The facility included examination rooms, clinical laboratories for standard and cardiopulmonary exercise stress testing, a conference room, a learning center with a teaching kitchen, and a body composition room with air displacement plethysmography, in addition to a 5000-sq-ft exercise center used for patients attending phase II and IV of CR.9
The exercise center consists of treadmills, elliptical machines, recumbent cycles, recumbent steppers, upright cycles, stair climbers, standard weight machines, free weights, exercise mats, walking track, stretching area, and an open area in the learning center. The CMP staff includes preventive cardiologists, exercise physiologists, registered dietitians, nurse practitioners, registered nurses, certified exercise specialists, behavioral change specialists, cardiopulmonary exercise test technicians, endocrinologists, and hypertension specialists. The CMP was designed to be an open enrollment program, with referrals from any department or self-reference of patients. The CMP is self-paid for most patients.
On the initial visit, patients had a 60-minute consultation with an exercise specialist who reviewed the program content and staff and patient expectations, performed baseline measurements, and assessed for risk stratification. Patients with substantial exercise limitations and fall risk were referred for evaluation to the Physical Medicine and Rehabilitation Department unless already being followed. A balance assessment was performed, and patients with poor balance were given balance exercise instructions. Patients completed a lifestyle questionnaire to assess baseline exercise and nutrition habits. Baseline vital measurements and a 6-Minute Walk Test were performed to assess initial exercise capacity.10 A body composition test was performed by air displacement plethysmography to obtain baseline body fat percentage.11
Program duration and content
The program duration and content are summarized in Table 1. The on-site portion of the program was completed in 6 weeks, followed by a 6-month followup period. Patients met with an exercise specialist for the 6-week evaluation and the 6-month followup to repeat measurements and assessments, discuss results, analyze potential reasons for suboptimal results, and set short- and long-term goals. After the 6-week evaluation, patients were given the option to continue to exercise in the phase IV CR program.9 Patients who did not choose this option continued to exercise on their own during the 6-month followup period. Attendance at the 6-month followup consultation marked completion of the program.
All CMP participants were required to attend a minimum of one 60-minute exercise session per week in the CR facility. Patients had the option of coming up to 5 days a week. Exercise was encouraged both on-site and outside the CR facility. Each patient was given a detailed, individualized exercise prescription in week 1 to progress into an active lifestyle at a reasonable pace. Recommendations for exercise included 150 to 300 minutes per week of a combination of aerobic exercise, stretching, and strength training. Aerobic exercise was recommended between 3 and ideally 6 sessions per week, lasting 30 to 60 minutes at a moderate-level intensity or rating of perceived exertion of 12 to 14.12 Aerobic exercise guidelines also included interval training consisting of 30 to 120 seconds of higher-intensity (rating of perceived exertion, 15–17) training followed by 60 to 120 seconds of lower-intensity (rating of perceived exertion, <14) training, 3 to 5 higher-intensity intervals per session for 2 to 3 sessions per week. Exercise intensity was prescribed on the basis of the symptom-limited stress test and included an individual target heart rate, combined with a recommended perceived exertion range noted earlier. Strength training was recommended 2 to 3 days per week for 10 to 15 minutes. Strength-training guidelines included using a combination of free weights, weight machines, calisthenics, and elastic bands to strengthen the major muscle groups, with 8 to 15 repetitions at a moderately challenging resistance and 1 to 3 sets of each strength training exercise.13 General physical activity throughout the day and avoiding prolonged periods of sitting were recommended. Each participant kept an activity log and was asked to record exercise at the on-site exercise sessions as well as exercise sessions outside the CR facility.
The weekly on-site 60-minute exercise sessions consisted of monitoring weight, heart rate, and blood pressure at rest and with exercise. Resting blood pressure was measured in a sitting position once at the beginning of each exercise session. Exercise blood pressure was measured once while they were exercising each session, about 15 minutes into the exercise. Exercise sessions typically included aerobic exercise by using the participant preferred modality and lasting 30 to 45 minutes, followed by 10 to 15 minutes of strength training. Warm-up and cooldown sessions, including low-level aerobic exercise and stretching, were incorporated before and after the aerobic exercise. Each participant was assigned to an exercise specialist and a registered nurse who managed the program and provided a safe environment along with education and encouragement.
Each patient had a 60-minute consultation with a registered dietitian to receive specific recommendations for energy intake and changes in diet. Patients attended a 60-minute nutrition class for further recommendations on healthy nutrition choices. Patients also attended a cooking demonstration where they learned to prepare healthy and tasty foods. Patients received a cookbook14 at the 6-week consultation.
The behavioral component was designed to provide motivation for ongoing cognitive and psychosocial support and assessment of making healthy lifestyle choices. Patients were required to attend a 60-minute behavioral change class once a week during the 6-week on-site portion of the program. This class was provided as a group session to foster ongoing support coordinated by a behavioral change specialist. The content of this class was based on a program for weight management, which was provided to the participant at the first session of the program.15 Content covered in this class included the following: (1) why is change so hard and goal setting, a lifestyle approach; (2) attitude/thinking traps and problem solving; (3) increasing physical activity, emotional eating, and relapse prevention; (4) self-monitoring and positive self-talk; and (5) social support and stress management. Classes included weekly suggested readings.15 Classes rotated every 6 weeks, and patients had the opportunity to make up a class if they missed one.
Measurements and assessments
The CMP group underwent laboratory assessments and anthropometric measurements at the initial visit, 6-week, and 6-month evaluation. Fasting laboratory assessments included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and fasting glucose levels. The anthropometric measurements included height, weight, and waist circumference. Standing height without shoes was measured in centimeters with 0.1 cm accuracy and rounded to the nearest 1 cm with a wall-mounted stadiometer. The patients were weighed on an electronic scale, with ±0.01 kg rounded to the nearest 0.1 kg. Waist circumference was measured at the midpoint between the lowest ribs and the iliac crest, using a measuring tape with 0.1 cm accuracy, rounded to the nearest 1 cm. Hemoglobin A1c, body composition, and balance assessment were not repeated until the 6-month followup. All laboratory results and assessments were reviewed with a CR registered nurse. Findings of significantly abnormal laboratory results required referral to a physician for further evaluation. Control 1 and control 2 groups continued with regular preventive cardiology outpatient visits and were given standard recommendations from medical staff. Further routine laboratory tests and regular assessments were used for the purpose of the study.
Descriptive statistics were performed for the study, and data are presented as mean ± SD for continuous variables and absolute numbers and percentages for categorical variables. Changes in continuous variables from baseline to 6 weeks, in addition to each patient group changes from baseline to 6 months, were assessed using the paired t test or signed rank test. Changes from baseline to 6 months were compared between groups by using the 2-sample t test or rank sum test. Because of incomplete assessment of waist circumference in the control groups, we used 2 or more metabolic criteria to define MetS for comparison between CMP and control groups. A P < .05 was used to determine statistical significance. All analyses were performed using JMP software version 9.0.1 (SAS Institute Inc, Cary, NC).
A total of 188 people signed up for the CMP during the study time, and 62 completed the program. Of them, 58 authorized use of their clinical information for research purposes. Of the 126 patients who never attended the CMP or dropped out early, 14 (11%) never showed up, 24 (19%) declined to participate before the fourth session, and 88 (70%) declined to participate at any point after the fourth session. Fifty-nine of these patients had followup data (control 1 group). Reasons why patients declined to continue participating in the program included the following: schedule conflicts, 19 (17%); did not meet their expectations, 10 (9%); transportation, 4 (4%); program cost, 7 (6%); and other/unknown, 72 (64%). Of the 126 patients who had not signed up for the CMP but had been seen in the outpatient preventive cardiology practice (control 2 group), 3 patients did not give authorization for use of their medical records (see the Figure).
Figure. Flowchart of...Image Tools
At 6 weeks of followup, in the CMP group, there was a significant reduction in weight (−2.21 ± 2 kg; P < .001); waist circumference in women (−3 ± 4.8 cm; P < .001) and in men (−2.5 ± 3.9 cm; P = .006); diastolic blood pressure (−6.5 ± 9 mm Hg; P < .001); total cholesterol (−15 ± 24 mg/dL; P < .001); and low-density lipoprotein cholesterol (−10 ± 19 mg/dL; P < .001). However, mean differences in systolic blood pressure, triglycerides, and fasting glucose showed no significant changes. Similar improvements were seen at the 6-month followup, in addition to a significant decrease in fasting glucose (−4.2 ± 2 mg/dL; P < .03).
Medications used at baseline and followup by the CMP, control 1, and control 2 groups are presented in Table 2. Baseline clinical characteristics along with the improvement in each outcome measure at 6 months of followup in the CMP, control 1, and control 2 groups are shown in Table 3.
When comparing the 6-month changes in the CMP and control 1 groups, those in the CMP group had more pronounced weight loss (−4.5 ± 5 kg vs −0.14 ± 6 kg; P < .001), decreased systolic blood pressure (−1.1 ± 17 mm Hg vs +9.6 ± 20 mm Hg; P = .004), and decreased diastolic blood pressure (−4.6 ± 11 mm Hg vs +3.4 ± 15 mm Hg; P = .002). Similarly, comparing the CMP group versus control 2 group, the CMP group had a more significant weight loss (−4.5 ± 5 kg vs −0.9 ± 3 kg; P < .001) and diastolic blood pressure reduction (−4.6 ± 11 mm Hg vs −0.7 ± 9 mm Hg; P = .02). General characteristic and outcomes of the CMP group by body mass index and glucose cutoffs are displayed at Table 4.
From the 32 patients who had MetS at baseline, 13 did not meet criteria for MetS after 6 weeks of followup and 22 (38%) lost at least 1 criterion for MetS. Changes in MetS components, using Adult Treatment Panel III criteria for the CMP group and body mass index as surrogate for waist circumference in all groups, are shown in Table 5. The number of MetS components per patient dropped significantly, favoring the CMP group compared with the control groups.
This study tested the effectiveness of a structured, multidisciplinary lifestyle intervention on MetS components by using the resources of a CR program. Our findings demonstrated significant improvement in anthropometric parameters such as weight, waist circumference, and other cardiometabolic factors and a reduction in the number of MetS components after the intervention. These results provide evidence of the effectiveness of lifestyle interventions for patients who completed the CMP compared with controls.
Metabolic syndrome is a condition that increases cardiovascular risk and mortality rates, with increasing prevalence over the latter years of life.16 Early identification, treatment, and prevention of MetS present a major challenge for physicians and public health care officials. Cardiac rehabilitation is an existing resource and, as we have demonstrated with this retrospective study, could be applied as a nonpharmacologic method that effectively encourages lifestyle changes and improvements in various cardiometabolic components.
Our results build on previous evidence that CR can help people improve their quality of life. Studies have shown a beneficial effect of implementing CR as an interventional strategy based on a multidisciplinary program for patients with considerable cardiovascular risk.17–20 However, few studies have analyzed CR targeted to people without cardiovascular diseases and focused particularly on MetS components. Specifically, body weight reduction plays an important role in decreasing cardiovascular risk, which is often difficult to achieve and maintain.21 Most studies assessing body weight changes by using CR settings have reported results that range from minimal to modest improvement. Lavie and Milani17 showed an average of 2% weight loss in a study of 235 individuals who participated in a 12-week program. Bader et al22 reported 1.9% to 4.3% weight reduction in a 10-week CR program with obese subjects. Our CMP group showed a body weight reduction of 2.1% at 6 weeks and 4.3% at 24 weeks, significantly better than either of our control groups.
Several studies have assessed the effectiveness of using the resources of CR programs beyond standard indications and focused to manage cardiovascular risk in patients with MetS. Rubenfire et al,8 through a 12-week lifestyle modification program using the resources of CR, demonstrated a trend toward improvement in systolic and diastolic blood pressure, triglycerides, high-density lipoprotein cholesterol, glucose levels, and waist circumference. In their study, all participants had to meet criteria for MetS, in addition to being represented mostly by type III obese population. In comparison, our study included people with MetS or being at risk for MetS because of obesity or impaired blood glucose, who were mostly type I obese individuals, further highlighting our preventative approach to this particular population. Studies outside CR have also been addressed. Katzmarzyk et al23 analyzed the contribution of regular exercise training on cardiometabolic factors in people with MetS and demonstrated an improvement in all cardiometabolic components. However, short-term outcomes were not assessed.
The major strengths of this study include the presence of 2 different control groups, which allowed us to compare cardiometabolic outcomes between the CMP participants and those who had the intention to be part of the CMP but did not do it and those attending a cardiovascular risk reduction clinic. Furthermore, the availability of an already established CR program in our institution facilitated the implementation of the CMP.
This study also had several limitations. Our study consisted of a small sample size with a high attrition rate. The fact that only 33% of the original group completed the program may reflect selection bias. However, our results come from an established CR program and not from a research cohort, and therefore, these are more likely to have shown real-life results. We believe that the low completion rate of this study was because of the fact that our sample included patients at risk for developing MetS who were asymptomatic, which might contribute to lower motivation for lifestyle changes and, therefore, lower compliance and higher likelihood of termination. Data collection did not include detailed socioeconomic characteristics or cognitive and behavioral factors that could explain the results or predict compliance. We were not able to assess information on compliance with exercise outside the rehabilitation center and to know their level of activity and compliance with diet at home. Waist circumference was not assessed in all groups. Balance test, 6-Minute Walk Test, lifestyle questionnaires, and body composition were not collected in their entirety. Therefore, changes or improvements in fat composition and distribution could not be compared among groups. Although we demonstrated short-term gains and improvements in MetS components for the 6 months of followup, the results are limited. There was minimal improvement in systolic blood pressure despite a significant weight reduction in the group that completed the program. This phenomenon has been observed in other studies.24 An explanation for this might be that most participants had blood pressures within the normal range at baseline and that 50% of the individuals were taking at least 1 antihypertensive medication before the study onset (Table 2). Finally, the staff in charge did not control the CMP medication use, so that at least part of the changes in several of the MetS components was partially or totally explained by the effect of medication change.
Despite these limitations, our study showed the beneficial effect of a supervised, multidisciplinary lifestyle intervention program as a valuable tool to improve MetS factors. This study demonstrated significant improvement in most of the cardiometabolic components, highlighting the components that are minimally affected by medication, such as body weight and waist circumference. Furthermore, we emphasized the existing resources of CR centers and the well-structured services offered during phase II CR. The possibility of expansion to people who may not qualify under current guidelines should be considered as suggested by the beneficial outcomes of our study.
Because of the expanding epidemic of MetS, it is important to redirect the program focus over this matter. Motivating patients can be challenging, but it is foremost important to seek for new methods to achieve compliance. In the aim of preventing MetS and future complications, we propose the CMP as a preventive resource that can be included in the management model. Finding the motivational techniques to encourage patients with MetS to pursue a healthier lifestyle has been 1 of the main struggles that health care has found, leading to increasing rates of cardiac heart disease because of the poor management of the cardiovascular risk factors that can be tackled at the initial phases, reducing the striking numbers of cardiovascular pathology incidence.
A lifestyle therapy program using the resources of a CR program is effective in individuals with or at risk for MetS, although enrollment and completion rates are low.
This study was supported by the European Regional Development Fund—Project FNUSA-ICRC (no. CZ.1.05/1.1.00/02.0123), and the grant sponsor was Ministry of Health of the Czech Republic (NT13434-4/20012).
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exercise; cardiac rehabilitation; lifestyle; metabolic syndrome; obesity; waist circumference