Maintenance phase of a physical activity intervention in older kidney transplant recipients: A 12-month follow-up

Abstract

Daily walking activities are associated with improving cardiovascular outcomes in older kidney transplant recipients. However, little is known regarding physical activity adherence outcomes in older kidney recipients. The purpose of this randomized controlled trial 12-month follow-up study was to evaluate the feasibility of the intervention (SystemCHANGE™ + activity tracker) during the maintenance period (7–12 months), compared to an attention-control group (activity tracker only) in older kidney recipients (age 60 and older). The sample included 60 participants (n = 30 IG; n = 30 ACG). Adherence rates for wearing the activity tracker daily were 96.5% in the IG and 80.8% in the ACG. The IG demonstrated within-group improvements for blood pressure at 12 months. Overall, there was a decrease in the average daily steps observed in both groups. These data suggest this intervention is feasible and additional boosters should be considered during the maintenance period to encourage physical activity.

Introduction

Multicomponent behavioral interventions using wearable technology and data-driven personal goal setting offer promise for addressing the modifiable risk factor of inactivity in older posttransplant kidney recipients. Less than 10% of kidney transplant recipients are considered adherent for engaging in daily physical activity and consuming a healthy diet.¹ Solid organ transplant recipients are especially prone to physical inactivity due to constellation barriers, including reduced physical function, being retired, and low self-confidence or low self-expectations after organ transplantation.² In kidney transplant recipients, age 50 and older, the lack of physical activity and sedentary lifestyle is correlated with vascular dysfunction and cardiovascular disease.³ Furthermore, cardiovascular disease is one of the leading causes of kidney allograft failure resulting in return to dialysis, retransplantation, chronic disease development, and death.⁴ These complications can often be mitigated in older adults by meeting the recommendations for physical activity (at least 150–300 minutes of moderate-intensity aerobic throughout the week or 75–150 minutes of vigorous-intensity activity throughout the week) and limit sedentary time.⁵ Notably, there are a limited number of organs available for transplantation, and the economic impact for kidney graft failure for a recipient is, on average, an additional $78,079 in medical costs.⁶ Regular physical activity reduces morbidity, mortality, and improves quality of life in kidney recipients.⁷

Because this population is at such high risk for complications, it is essential for the transplant health care team to implement innovative strategies to assist transplant recipients in reducing modifiable risk factors. One such strategy is the use of self-monitoring or tracking modifiable behaviors that ultimately may improve adherence for lifestyle modifications, such as participating in daily physical activity. Recently, studies have found that using self-monitoring technology, such as an activity tracker, is an effective method for tracking physical activity and providing individual feedback, thereby assisting patients with meeting their activity and weight goals.⁸

Historically, the standard of care used by the transplant team is to educate solid organ transplant patients about healthy lifestyle prior to being discharged from the hospital using printed education materials. These education materials often include information about dietary restriction, postsurgical physical restriction, the need for vital signs monitoring, and medication compliance.⁹ Dietary counseling is usually provided to the posttransplant recipient via one to four consultation visits by a dietitian.¹⁰ Thus, exercise and lifestyle counseling are not included in standard posttransplant care.¹⁰ Given the well-established challenge of promoting lifestyle modifications following transplantation, integrating a technology-supported self-monitoring approach holds promise for promoting favorable physical activity adherence in older kidney recipients.

There is a gap in knowledge regarding physical activity adherence outcomes using an activity tracker among older kidney recipients.¹¹ The purpose of this pilot randomized controlled trial was to evaluate the adherence rates of a 12-month follow-up of a multicomponent physical activity intervention called SystemCHANGE™ + activity tracker. Our intervention (SystemCHANGE™ + activity tracker) was adapted from the SystemCHANGE™ (Change Habits by Applying New Goals and Experience) paradigm.¹² The objective of the study was to determine the primary outcome for feasibility of the adherence of the intervention during the maintenance period (post-intervention period 7 months to 12 months) on daily steps and health outcomes (blood pressure, heart rate, and waist circumstance). We hypothesized that the SystemCHANGE™ + activity tracker intervention would improve adherence rates for wearing the activity tracker, daily steps, and health outcomes compared to the attention-control group.

Methods

Study design

This was a 12-month follow-up study of a single site, randomized controlled trial. The parent study design was a parallel randomized controlled trial using repeated measures from baseline to 6 months.¹³ Prior to the parent study, Institutional Review Board approval was obtained from The Ohio State University, and informed consent was obtained from each participant.¹³ The participants were randomized 1:1 to the intervention arm or the attention-control arm using a permuted block randomization scheme generated by the study statistician. Participants and research assistants were blinded to the group assignment. We determined the sample size based on anticipated effects sizes and attrition from a previous physical activity step study.¹⁴

Eligibility criteria for this study consisted of kidney recipients, age 60 years or older, not on dialysis, ability to speak English, possession of a smartphone, no use of assistive devices for walking, and at least 3 months or longer post-transplant. Participants were not eligible for the study if they were participating in a weight loss program or structured exercise program and unable to pass brief cognitive screening test.¹⁵

Setting

Participants were recruited from a Midwest transplant center over a nine-month period using a convenience sampling strategy. During the active phase (baseline to 6 months) of the study, participants met once a month in a face-to-face group setting. For the maintenance phase, in which the research team had no face-to-face contact with the participants, the participants were asked to complete the study activities within their home setting.

Procedure for research activities

Our intervention has theoretical underpinnings in the Plan-Do-Study-Act Model.¹⁶ The intervention began with the development of a “Plan” (individual goals for daily steps) and identifying possible ways (personalized-system solution) to achieve daily physical activity (steps). For the “Do” component, participants incorporate their personalized-system solution into existing routines. The “Study” component enables the participants to evaluate their daily step goal progress with visual feedback (real-time data) from the activity tracker. The “Act” phase allows the participants to evaluate the personal-system solution and determine if the daily step goal was achieved and to modify their plan as necessary.

The intervention group received Fitbit Charge 2™ and received instructions for using the Systems improvement approach that included setting personal step goals, evaluating feedback from the activity tracker for meeting daily step goals, and making adjustments to personal routines to achieve daily step goals. The attention-control group received Fitbit Charge 2™ and educational information about healthy lifestyle choices after transplant. The active phase of the study lasted six months, in which both arms attended a one-hour monthly face-to-face group session.¹³ At the beginning of month seven, the maintenance phase (no contact with the research team) began and extended for six months. We defined a non-adherent day as 300 steps or fewer per day for performing the research activities (achieving steps). The value of 300 steps was based on inspection of our raw data as well as observed ranges of step counts in previous studies.¹⁷ No changes were made to the study protocol throughout the study.

Treatment fidelity

Treatment fidelity in the active phase was maintained by a protocol checklist which was developed using Bellg and colleagues¹⁸ best practices to ensure standardized delivery of the protocol. The checklist included all steps needed to complete each session and a log of time taken for each session. To determine participant understanding of the intervention, each participant was assessed on their monthly progress for using the activity tracker via the activity tracker reports generated via Fitabase (real-time remote monitoring of step data that syncs the data from the Fitbit).¹⁹ The attention-control group’s understanding of the research activities was determined by the participants stating their comprehension of the transplant educational information delivered each month.

Data collection

Study participants and research assistants directly entered the data by using electronic research forms via a password-protected tablet using Research Electronic Data Capture (REDCap), at 12 months. Participant daily steps were synced from the activity tracker to the Fitabase system.¹⁹ While the participant was in a seated position with both feet flat on the floor, a wireless BP cuff placed on the person’s upper arm assessed the blood pressure (BP) and resting heart rate (HR). The research assistant measured the participant’s waist circumference (WC) between the lilac crest and the lower anterior ribs with the person standing upright using a tape measure.

Data analysis

Descriptive statistics were used to summarize the monthly aggregated average for daily steps and health outcomes at 12 months. An intent-to-treat analysis was used to address the daily steps and health outcomes. For the number of daily steps, we used mixed-effects linear regression modeling to model the daily steps as a linear combination of the fixed-effects of group (intervention vs. attention-control), months (baseline to 7–12 months), and group by months interaction, adjusting for within-subject clustering of daily repeated measures using subject-specific random intercepts with a first-order autocorrelation. From the model, we derived estimates on the 1) monthly average daily steps for each group in each month, 2) between-group comparisons (intervention vs. attention-control) of the average daily steps for each month, and 3) between-group comparisons of the change in average daily steps from 7 months to 12 months. Similarly, we used mixed-effects linear regression modeling to derive estimates for each health outcome (blood pressure [BP], heart rate [HR], and waist circumference [WC]). These estimates included: 1) group-specific means at each time point (Baseline and 12 months), 2) between-group comparisons of mean outcome at each time point, and 3) between-group comparisons of change from baseline to 12 months. We conducted all analyses using Statistical Analysis System (SAS) 9.4.

Results

The original sample consisted of 60 participants. However, at the start of the maintenance period (Month 7) the sample consisted of (n = 25 intervention, and n = 25 control). At the 12-month follow-up visit (see Figure 1), the total study attrition rate was 23% [N =46, n = 2 dropped in the intervention group (Month 12) and n = 2 dropped (Month 12)] in the attention-control group (see Figure 1 for reasons participants were lost to follow-up).

Figure 1.

Individual Randomized Controlled Trial of a Physical Activity Intervention for Kidney Transplant Recipients

Sample

There were no statistically significant differences between groups on the variables of age, ethnicity, race, income, employment status, and time since transplant¹³. The mean age of the participants in the intervention group was 65.7 ± 4.9 years and the mean age in attention-control group was 65.1± 4 years. The majority of participants in both groups were males [intervention n = 16 and attention-control n = 19]. Most of the participants were white [intervention n = 16 and attention-control n = 14)] and Non- Hispanic [intervention n = 27 and attention-control n = 25]. The greatest portion of participants had at least an associates or higher degree [intervention n = 15 and attention-control n = 16] and received an income higher than $20,000.00 a year [intervention n = 21 and attention-control n = 25]. The average time since transplantation in the intervention group was 7.0 ± 5.7 years and in the attention-control was.7.2 ± 6.5 years.

Adherence

After 12 months, a high rate of adherence was found for wearing the activity tracker each day to monitor daily steps among the 46 participants who completed the study. The adherence rates at 12 months were significantly higher in the intervention group than in the attention-control group [96.5% versus 80.8%, p < 0.001] with odds ratio of 6.6 [95% CI = 2.1–21.2].

Steps

Based on monthly aggregated average daily steps, the intervention group increased their steps from baseline to 12 months by 334 steps per day, whereas the attention-control group demonstrated a decrease in steps by 563 steps per day. Interestingly, we observed a decrease in the average daily steps in the intervention group from month 8 to month 11 and a decrease in the average daily steps in the control group from month 7 to month 12, with a slight increase month 8. We found a mean difference of 1041± 2440 (ES = 0.43) in daily steps between the groups from baseline to 12 months (Table 1).

Table 1.

Older kidney recipients average daily steps in the intervention versus. attention-control groups during the maintenance phase

	Average daily steps				Change from baseline
Time	Intervention		Control		Intervention				Control				Intervention vs. Control
	Mean	SD	Mean	SD	Mean	SD	ES	P	Mean	SD	ES	P	Mean	SD	ES	P
Baseline	4432	1865	4171	1709	-	-	-	-	-	-	-	-	-	-	-	-
Month 7	4941	2631	4004	2959	485	2008	0.24	0.25	−233	2628	−0.09	0.66	718	2345	0.31	0.29
Month 8	4481	2781	4177	3078	25	2007	0.01	0.95	−61	2725	−0.02	0.91	86	2400	0.04	0.90
Month 9	4405	3009	3987	2852	−51	2133	−0.02	0.91	−251	2702	−0.09	0.65	200	2440	0.08	0.78
Month 10	4362	2899	4079	2557	−94	2347	−0.04	0.85	−159	2250	−0.07	0.73	65	2298	0.03	0.92
Month 11	4627	2858	3634	3002	171	2317	0.07	0.72	−604	2451	−0.25	0.23	775	2386	0.32	0.26
Month 12	4766	3114	3608	2985	412	2243	0.18	0.39	−630	2607	−0.24	0.24	1041	2440	0.43	0.15

SD, standard deviation, ES effect size (Cohen’s d)

p < 0.05, significantly different

Blood pressure

Both groups demonstrated improvements in BP from baseline to 12 months, although the differences in the attention-control group were statistically non-significant. We found significant improvements in the intervention group for both systolic and diastolic blood pressure from baseline to 12 months [mean systolic blood pressure (SBP) 142 ± 24 versus 12 months, mean SBP 132 ± 14.8; p = 0.03, mean diastolic blood pressure (DBP) 80 ± 14.8 versus 12 months mean DBP 74 ± 10.1; p = 0.04]. No significant improvements for BP were found in the attention-control group from baseline [baseline mean SBP 150 ±19.1 versus 12 months, mean SBP 144 ± 12.8; p = 0.16 and baseline mean DBP 80 ±10.0 versus 12 months, mean DBP 77 ±10.2; p = 0.27]. Additionally, no between group differences were found in blood pressure from baseline to 12 months (Table 2).

Table 2.

Older kidney recipients health outcomes of intervention versus attention-control groups from baseline to 12 months

Variable	Baseline		12 Mons		Change from Baseline to 12 Mons
Systolic Blood Pressure	Mean	SD	Mean	SD	Mean	SD	ES	P
Intervention	141.8	24.28	132.2	14.8	−12.14	23.58	−0.51	0.03
Attention-Control	150.2	19.05	143.8	12.76	−5.79	19.52	−0.30	0.16
Intervention versus Attention-Control					−6.34	21.55	−0.29	0.33
Diastolic Blood Pressure
Intervention	80.16	14.82	74.05	10.19	−7.64	16.52	−0.46	0.04
Attention-Control	79.64	10.02	77.38	10.21	−2.25	9.82	−0.23	0.27
Intervention versus Attention- Control					−5.39	13.44	−0.40	0.19
Heart Rate
Intervention	74.36	10.83	66.82	7.76	−5.73	9.94	−0.58	0.01
Attention-Control	70.68	10.36	67.21	8.20	−2.83	7.78	−0.36	0.09
Intervention versus Attention- Control					−2.89	8.88	−0.33	0.28
Waist Circumference
Intervention	40.54	5.21	38.70	5.42	−1.86	2.22	−0.84	<0.001
Attention-Control	40.94	5.13	38.42	4.66	−2.44	1.99	−1.23	<0.001
Intervention versus Attention- Control				0.57		2.10	0.27	0.36

Heart rate

Both groups demonstrated improvements in HR from baseline to 12 months. Although significant improvements were found in lowering heart rate for the intervention group from baseline [mean 74.4 bpm ± 10.8] versus 12 months [mean 66.8 bpm ± 7.8; p = 0.01], heart rate remained unchanged for the attention-control group mean at baseline [70.7bpm ± 10.4] versus 12 months [mean 67.2 bpm ± 8.20; p = 0.09]. However, no significant between-group difference was found in heart rate from baseline to 12 months (Table 2).

Waist circumference

A decrease was found in the average waist circumference among participants in both groups from baseline to 12 months. However, no between-group difference was found in waist circumference from baseline to 12 months (Table 2).

Discussion

Our study adds valuable information to the scientific literature about daily walking adherence and health outcomes for older kidney recipients. We established that the intervention group had greater adherence rates for wearing the activity tracker and higher total daily steps than the attention-control group from baseline to 12 months. This finding is important as adherence to regular physical activity is one of the most important factors affecting health and longevity in older adults among all racial and ethnic groups.²⁰ Interestingly, the World Health Organization stated 15 years ago that no single strategy has been deemed optimal for the measurement of physical activity adherence and that a multimethod approach that combines objective measures is needed to measure adherence in physical activity.²¹ Our study aligns with this recommendation, in which the daily steps were recorded in real time combined with a process in which a person reviewed their step data and compared it to their step goals that were linked to personal routines. Previous literature has defined physical activity adherence in one of these four categories: (a) completion and retention adherence, (b) attendance adherence, (c) duration adherence, and (d) intensity adherence.²² We defined daily walking adherence in our study based on the 12-month completion for wearing the activity tracker each day and the achievement for the number of steps (greater than 300 steps per day) taken each day. Our adherence rate was extremely high (96.5%) in the intervention group. Previous systematic reviews indicated that with older adults, adherences rates for completed exercise programs ranged between 65% to 85%, and the average physical activity exercise session completed at home ranged from 1.5 to 3 times over a week.^19,20 In the present study, participants completed the daily walking activities in their own home or community. Notably, we found a decrease in both groups for average daily steps during the maintenance phase compared to the active phase.¹³ This finding, perhaps, suggests the need for additional boosters to encourage physical activity during the maintenance phase. Based on our finding from the literature, we recommend sending bimonthly text messages during the maintenance phase.²³

In addition to the high adherence rate for wearing the activity tracker and the need for an additional booster to encourage daily steps, we found possible clinical significance for improved BP control in the intervention group. The BP data for the intervention group indicated significant improvements within the group for the systolic and diastolic from baseline to 12 months. Although our study was not powered to detect the effectiveness of the intervention, this finding is potentially clinically significant for moving the intervention group toward alignment to the American Heart Association Stages of Hypertension²⁴ from Stage 2 (systolic > 140 mm Hg and diastolic > 90 mm Hg ) at baseline to a Stage 1 hypertension (systolic 130–139 mm Hg and diastolic 80–89 mm Hg ) at 12 months. According to Lee and colleagues, blood pressures that are less than 140/90 mm Hg are associated with a reduction in mortality, stroke, and end-stage renal disease, outcomes that are extremely important in this patient population.²⁵ A recent systematic review found evidence that even low levels of walking activity that included taking an additional 1,000 steps per day were associated with lower risk of all-cause mortality and lower cardiovascular disease morbidity/mortality.²⁶ This finding may explain the improvement in BP and heart rate in the intervention group. These findings underscore the promise of the SystemCHANGE™ + activity tracker multicomponent physical activity intervention for promoting physical activity among older kidney transplant patients and further amplify the need to examine the utility of this intervention in a future, large-scale optimally powered effectiveness trial.

Although the present findings are promising and contribute to a more comprehensive understanding of the benefits of the SystemCHANGE™ + activity tracker intervention for promoting physical activity among older kidney transplant patients, there are select limitations that should be considered when interpreting the results. The study may not be generalizable to all kidney transplant recipients, as we included only older adults who did not use an assistive device such as a cane or walker to ambulate. Also, we did not examine the reasons participants were not adherent for participating in daily step activity. The literature suggests that we should consider factors such as age, gender, race, ethnicity, education, cognitive status, prior physical activity, lack of social support, and a lack of access to an environment for participating in physical activity.²⁰ We did not collect data for comorbidities and medication, two confounding factors that may have contributed to improvement in BP. Lastly, we did not examine the minutes per day of physical activity, only the number of steps per day. Future large, randomized controlled trial studies are needed to determine the effects of our multicomponent walking intervention on minutes of physical activity to improve cardiovascular health in older kidney recipients.

Conclusions

The results of our study suggests the need for additional booster to maintain physical activity during the maintenance period of clinical trials. This finding is important for nurse scientists who are planning to implement a physical activity intervention. Lastly, nurse scientists should consider collecting data for medication adjustments, comorbidities, and reasons for nonadherence in daily step activity to provide a more comprehensive explanation of clinical findings and health outcomes.

Highlights.

• Daily walking activities are associated with improving cardiovascular outcomes in older adults.

• Multicomponent interventions using goal setting, objective feedback data, and personalized plans holds promise to promote daily walking activity among older kidney transplant recipients.

• We found high adherence rates for wearing an activity tracker daily for 12 months, but additional boosters are needed to encourage physical activity.