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Medicine & Science in Sports & Exercise:
doi: 10.1249/mss.0b013e3181586b41
APPLIED SCIENCES: Psychobiology and Behavioral Strategies

Maintenance of Physical Activity in Breast Cancer Survivors after a Randomized Trial

VALLANCE, JEFFREY K.1; COURNEYA, KERRY S.1; PLOTNIKOFF, RONALD C.1,2; DINU, IRINA2; MACKEY, JOHN R.3

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Author Information

1Faculty of Physical Education and Recreation, 2School of Public Health, and 3Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, CANADA

Address for correspondence: Kerry S. Courneya, Ph.D., Faculty of Physical Education and Recreation, University of Alberta, E-488 Van Vliet Centre, Edmonton, Alberta, T6G-2H9, Canada; E-mail: kerry.courneya@ualberta.ca.

Submitted for publication May 2007.

Accepted for publication August 2007.

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Abstract

Purpose: The purpose of this study was to examine the longer-term effects of pedometers and print materials on changes in physical activity (PA) and health-related quality of life (HRQoL) in breast cancer survivors who participated in a 3-month behavior change intervention.

Methods: Breast cancer survivors (N = 377) were randomly assigned to receive either (a) a standard public health recommendation for PA (SR), (b) previously developed breast cancer-specific PA print materials (PM), (c) a step pedometer (PED), or (d) a combination of the two (COM). The primary endpoint was self-reported moderate/vigorous PA minutes per week at 6-month follow-up after the initial 3-month intervention period.

Results: Seventy-one percent (266/377) of participants completed the 6-month follow-up assessment. According to intention-to-treat linear mixed-model analyses, self-reported moderate to vigorous PA increased by 9 min·wk−1 in the SR group compared with 39 min·wk−1 in the PM group (mean difference = 30 min·wk−1; 95% CI = −44 to 104; P = 0.425), 69 min·wk−1 in the PED group (mean difference = 60 min·wk−1; 95% CI = −13 to 132; P = 0.107), and 56 min·wk−1 in the COM group (mean difference = 47 min·wk−1; 95% CI = −26 to 119; P = 0.210). The same pattern was observed for self-reported, brisk walking. No differences were found for HRQoL or fatigue.

Conclusion(s): Breast cancer-specific PM and PED did not maintain significantly higher PA or HRQoL at 6-month follow-up in breast cancer survivors, but the magnitude of the effect on PA (30-60 min·wk−1) was consistent with the immediate postintervention effect observed at the 3-month postintervention time point. Issues of power resulting from additional loss to follow-up may account for the failure to achieve statistical significance. Additional research with larger sample sizes and more complete follow-up is warranted.

Scientific evidence supports the role of physical activity (PA) as a safe and effective intervention to improve health-related quality of life (HRQoL) and possibly even survival in breast cancer survivors (22,23). Indeed, a recent prospective cohort study of almost 3000 breast cancer survivors reported that higher levels of PA were associated with reduced risks of breast cancer death and breast cancer recurrence (16). Despite the reported benefits of PA, the majority of breast cancer survivors are not meeting public health guidelines (at least 150 min·wk−1 of moderate- to vigorous-intensity PA (26)) (18,19).

Given these findings, we recently tested an intervention designed to increase PA behavior in breast cancer survivors. The Activity Promotion (ACTION) trial was a randomized controlled trial designed to determine the effects of breast cancer-specific PA print materials (PM), a step pedometer (PED), or their combination (COM), on PA and HRQoL in breast cancer survivors compared with a group receiving a standard public health recommendation for PA (SR). We previously reported that, at the 3-month postintervention assessment, breast cancer-specific PA PM and PED were effective strategies for increasing PA and HRQoL in breast cancer survivors (31). Specifically, moderate- to vigorous-intensity PA increased by about 40-60 min·wk−1 in the intervention groups compared with the SR group, and brisk walking increased by about 60-90 min·wk−1. The COM group also reported significantly better HRQoL and reduced fatigue compared with the SR group.

PA intervention researchers are faced with the challenge of developing effective strategies aimed at facilitating PA behavior maintenance once PA adoption has been established (1). Successful PA behavior maintenance has been defined as engaging in regular PA for at least 6 months after the end of an intervention. PA behavior interventions implementing PM have suggested some promise in facilitating PA behavior maintenance (1,21,24). To this end, Craig et al. (8) have suggested that health behaviors such as PA may be improved by combining health-related messages with user-friendly self-monitoring tools (e.g., PED, accelerometers).

Here, we report the 6-month follow-up effects of the breast cancer-specific PM and PED on PA behavior and HRQoL (9 months after randomization). We hypothesized that survivors in the PM, PED, and COM groups would maintain significantly higher self-reported PA and brisk walking at 6-month follow-up compared with the SR group. We also hypothesized that the COM group would maintain its HRQoL and fatigue advantage over the SR group at the 6-month follow-up time point.

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PARTICIPANTS AND METHODS

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Study setting.

The trial design and protocol have been previously described (31). In brief, the trial was conducted at the University of Alberta (Edmonton, Alberta, Canada). Ethical approval was received from the Alberta Cancer Board and the University of Alberta. Written informed consent was obtained for all procedures.

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Participants.

Eligibility criteria included (a) histologically confirmed stage I-IIIa breast cancer, (b) physician approval, (c) free from chronic medical and orthopedic conditions that would preclude PA (e.g., congestive heart failure, use of a mobility aid, recent knee or hip replacement), (d) ability to read and understand English, (e) completed adjuvant therapy except hormone therapy, (f) no current breast cancer, and (g) interested in increasing PA.

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Design and recruitment.

The study was a four-armed, prospective, randomized, controlled trial. The Alberta Cancer Registry was used to identify breast cancer survivors residing in northern Alberta, Canada diagnosed between January 2000 and December 2003. The trial was conducted between July 2005 and April 2006. Each survivor's physician was required to provide approval to participate in the study. Each approved survivor was sent a letter of invitation. Interested and eligible survivors were then mailed a baseline assessment package that contained (a) cover letter, (b) consent forms, (c) baseline questionnaire, (d) PED, and (e) postage-paid business reply envelope. Before randomization, all survivors were required to complete and submit all baseline assessments. Participants were informed at the time of recruitment that they would be contacted 6 months after completion of the 3-month intervention to assess PA and HRQoL. There was no contact with participants by any member of the research team during the 6-month follow-up period. At the 6-month follow-up time point, all survivors were sent an assessment package via post. Participants were considered lost to follow-up if no response was received after two attempts to contact the participant by mail.

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Random assignment to groups.

Survivors were randomly assigned to one of four groups in a 1:1:1:1 ratio, using a computer-generated random-numbers list (GraphPad Software, San Diego, CA). A research assistant generated the group assignments in sequentially numbered, sealed, opaque envelopes. The envelopes were concealed from the project coordinator. Survivors were notified via telephone of their random group allocation the following day (SR, PM, PED, or COM).

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Intervention groups.

At the time of randomization notification, all groups received a standard recommendation, via telephone, to perform 30 min of moderate to vigorous PA on 5 d·wk−1. The SR group received no further intervention materials. The three intervention groups received the relevant intervention materials via post after randomization. The PM group received a copy of Exercise for Health: An Exercise Guide for Breast Cancer Survivors. A detailed description of the guidebook is published elsewhere (32). The PED group received a Digi-Walker SW-200 PED (New Lifestyles Inc., Lee's Summit, MO) and a 3-month step calendar. The COM group received both interventions (PM and PED). Survivors randomized to the COM and PED groups were instructed to wear their PED every day for the 3-month duration of the study (i.e., 84 d) and to record their daily step totals at the end of each day. Participants in the SR and PM groups were instructed to refrain from using their PED in between assessments. Survivors were not instructed to achieve a particular step target (e.g., 10,000 steps).

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Primary and secondary outcomes.

The primary outcome was change in self-reported moderate to vigorous PA. Secondary outcomes were changes in HRQoL, fatigue, and self-reported brisk walking. Outcomes were assessed at baseline (before randomization), 3 months after randomization, and 6-month follow-up (9 months after randomization).

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Measures.

Demographic and medical characteristics were assessed at baseline and included age, marital status, education, family income, employment status, height, weight, comorbidities, body mass index (BMI), and menopausal status. Medical data were extracted from the Alberta Cancer Registry and included tumor stage and grade, treatment(s) received, and time since diagnosis.

At the 6-month follow-up time point, survivors in the two groups that received a pedometer (PED and COM) were asked whether they continued to wear their PED during the follow-up period. These survivors were also asked (yes/no) whether they felt that the PED had helped them increase their PA behavior. One open-ended question asked survivors why they felt the PED had helped increase their PA behavior. Adherence to the guidebook during follow-up was assessed by asking survivors (PM and COM groups) how many times they had read the entire guidebook and how long they had spent reading the guidebook. One open-ended question asked survivors what aspects they liked about the guidebook.

Self-reported PA was assessed at baseline, 3 months after randomization, and at 6-month follow-up, by the leisure score index (LSI) of the Godin Leisure-Time Exercise Questionnaire (GLTEQ) (14). The LSI contains three questions that assess the average frequency of mild, moderate, and strenuous exercise during free time in a typical week in the past month. For each intensity category, survivors were given examples of exercises that are appropriate for each category. We modified the LSI so that average duration was also provided. For the present study, we calculated the total minutes of moderate plus strenuous exercise for each of the three time periods (baseline, 3 months after randomization, 6-month follow-up). An independent evaluation of the GLTEQ found its reliability to compare favorably with nine other self-reported measures of exercise based on various criteria, including test-retest scores, objective activity monitors, and fitness indices (20).

We also assessed self-reported brisk walking at all three time points, using the LSI format. The item assessed the average frequency and duration of brisk walking (defined as walking like you were late for an appointment) during a typical week in the past month. PED steps were not evaluated at the 6-month follow-up time point.

HRQoL at all three time points was assessed by the Functional Assessment of Cancer Therapy-Breast (FACT-B) scale (2,7). The FACT scale contains items pertaining to the consequences of a cancer diagnosis and its related treatments (e.g., fatigue, symptom expression). Sample FACT items include I have a lack of energy, I am bothered by a change in weight, and I am bothered by side effects of treatment. Fatigue was assessed using the fatigue scale (FS) (4) from the FACT measurement system. Sample FS items include I feel tired, I am frustrated by being too tired to do the things I want to, and I have energy. All FACT questions are rated on a five-point Likert-type scale that ranges from 0 = not at all to 4 = very much. On all HRQoL subscales, higher scores represent better HRQoL, or less severe symptoms. The FACT scales are brief, easy to administer, and have suitable evidence of internal consistency, test-retest reliability, convergent and discriminant validity, and comparability to other widely used HRQoL scales in the cancer domain (e.g., EORTC QLQ C-30) (2,4,7,17). Evidence also indicates that the FACT is sensitive to change (5,6).

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Statistical analyses.

For all analyses, we employed the intention-to-treat (ITT) approach (25). Linear mixed-model analyses (11) were used to assess differences in group changes from baseline to 6-month follow-up. Linear mixed models use all available data and provide a valid analysis when data are missing at random. As a sensitivity analysis, we also analyzed the data for completers only (71% completing the follow-up time point). There were no substantive differences among the two analytical approaches, and the conclusions drawn from each analysis did not differ. Therefore, we present the results from the mixed-model analyses. For all self-reported PA and walking data, outliers (i.e., Z-score > 3.29) remained in the data (N = 14 at baseline; N = 10 at 3 months after randomization; N = 3 at 6-month follow-up) but were adjusted to be one unit less than the next-most-extreme score (29). The primary hypothesized comparisons were the three intervention groups (PM, PED, and COM) compared with SR. Comparisons were performed for all primary and secondary outcomes. Given the planned and a priori nature of our research questions, no corrections were made for multiple comparisons.

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RESULTS

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Flow of participants through the trial.

Flow of participants through the trial has been reported elsewhere (31). To summarize, we randomized 377 breast cancer survivors to four study groups: SR (N = 96), PM (N = 94), PED (N = 94), and COM (N = 93). Overall retention was 71% (266/377) at the 6-month follow-up time point and did not statistically differ among groups (P = 0.699). Retention across the four study groups was as follows: SR (N = 68), PM (N = 62), PED (N = 69), and COM (N = 67).

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Baseline characteristics and sample generalizability.

Baseline demographic, medical, and behavioral characteristics for all randomized survivors are presented elsewhere (31). Groups were balanced on all study measures, except that the PED group had a higher proportion of postmenopausal survivors (P = 0.017). We found no substantial differences between our sample of survivors (N = 377) and nonparticipants (N = 1213) on the medical variables we had available to us (months since diagnosis, breast cancer morphology, breast cancer stage, and treatment(s) received). Baseline characteristics for survivors completing the 6-month follow-up assessments (i.e., completers) and those survivors that were lost to follow-up at 6 months (i.e., noncompleters) are presented in Table 1. In comparing completers (N = 266) with noncompleters (N = 111), we found no differences in the majority of sociodemographic (age, education, income, employment, ethnicity, residence) and medical variables (months since diagnosis, breast cancer stage, treatment(s) received, BMI). We found that completers weighed less (3.5 kg less), were more likely to be on Tamoxifen, and were more likely to be meeting PA guidelines at baseline, than noncompleters. Moreover, we found no significant differences in changes in self-reported PA, brisk walking, or any of the HRQoL variables between completers and noncompleters at the 3-month time point (i.e., postintervention).

Table 1
Table 1
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Adherence to the intervention materials at 6-month follow-up.

Of the survivors in the two groups who received a PED, (COM and PED; N = 136) 38.5% (N = 52) reported that they continued to wear their PED during the 6-month follow-up period. The most frequently reported reasons for not continuing to wear the PED were 1) forgot/lost it (forgot: N = 15; lost: N = 8; 27%), 2) PED was awkward (N = 10; 12%), and 3) PED malfunctioned/did not work (N = 8; 10%). Among the survivors, 78.8% (N = 104) felt that the PED had helped them increase their PA behavior. The most frequently reported reasons why participants felt the PED had helped increase their PA behavior were 1) PED was motivating/encouraging (N = 42; 40%) and 2) participants knew how much they were doing/had increased awareness (N = 35; 34%). Survivors in the two groups that received PM (COM and PM; N = 127) reported reading the entire PM an average of 1.3 times for an average of 42 min during the 6-month follow-up period. Sixty percent of survivors reported reading the PM at least once, whereas 34% reported reading the PM for at least 30min.

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Changes in self-reported PA.

Table 2 presents the PA data. From baseline to 6-month follow-up, self-reported moderate to vigorous PA increased by 9 min·wk−1 in the SR group compared with 39 min·wk−1 in the PM group (mean difference = 30 min·wk−1; 95% CI = −44 to 104; P= 0.425), 69 min·wk−1 in the PED group (mean difference = 60 min·wk−1; 95% CI = −13 to 132; P = 0.107), and 56 min·wk−1 in the COM group (mean difference = 47 min·wk−1; 95% CI = −26 to 119; P = 0.210). Self-reported brisk walking decreased in the SR group by −6 min·wk−1 compared with an increase of 29 min·wk−1 in the PM group (mean difference = 35 min·wk−1; 95% CI = −20 to 91; P = 0.217), 36 min·wk−1 in the PED group (mean difference = 43 min·wk−1; 95% CI= −12 to 98; P = 0.127), and 41 min·wk−1 in the COM group (mean difference = 47 min·wk−1; 95% CI = −8.3 to 102; P = 0.096).

Table 2
Table 2
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Maintenance of PA.

Table 3 presents the PA change from 3 months after randomization to 6-month follow-up (i.e., maintenance). From 3 months after randomization to 6-month follow-up, self-reported moderate to vigorous PA decreased by −23 min·wk−1 in the SR group (P = 0.372) compared with −33 min·wk−1 in the PM group (mean difference = −9 min·wk−1; 95% CI = −85 to 67; P = 0.823), −22 min·wk−1 in the PED group (mean difference = 2 min·wk−1; 95% CI = −71 to 76; P = 0.953), and −37 min·wk−1 in the COM group (mean difference = 12 min·wk−1; 95% CI = −88 to 62; P = 0.733). Self-reported brisk walking decreased in the SR group by −8 min·wk−1 (P = 0.749) compared with −47 min·wk−1 in the PM group (mean difference = −39 min·wk−1; 95% CI = −108 to 31; P = 0.273), −57 min·wk−1 in the PED group (mean difference = −49 min·wk−1; 95% CI = −117 to 19; P = 0.155), and −17 min·wk−1 in the COM group (mean difference = −9 min·wk−1; 95% CI = −77 to 60; P = 0.800).

Table 3
Table 3
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Changes in quality of life and fatigue.

There were no significant or clinically meaningful differences between groups on the HRQoL and fatigue measures from (a) baseline to 6-month follow-up or from (b) 3 months after intervention to 6-month follow-up. There were no significant differences between any of the groups on self-reported BMI.

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DISCUSSION

Our results indicate that none of our three intervention groups (PM, PED, and COM) were statistically superior to SR for PA (self-reported PA and brisk walking) or HRQoL (HRQoL and fatigue) at 6-month follow-up, although the COM and PED groups showed trends for PA and walking. The differences in PA at 6-month follow-up, although not statistically significant, were consistent with our 3-month postintervention effects-which were statistically significant-and they may be clinically meaningful. Specifically, we previously reported that the intervention groups performed 40-60 min·wk−1 more of PA and 60-90 min·wk−1 more of brisk walking compared with the SR group at postintervention (i.e., 3 months) (31). At 6-month follow-up, our results indicate that the intervention groups reported 30-60 min·wk−1 more of PA and 35-50 min·wk−1 more of brisk walking compared with the SR group. This difference of 30-60 min·wk−1 of PA is equivalent to one to two extra days of PA per week (assuming 30 min·d−1, as per public health recommendations) and may have meaningful effects on health outcomes. Consequently, there was only a small decline in the magnitude of the effect of our interventions during the 6-month follow-up period. Additional maintenance analysis from 3 months after randomization to the 6-month follow-up time point indicated that survivors in all four groups reported decreases in both PA and brisk walking behavior. With the exception of the SR group, the decrease was similar across groups. As we reported earlier (31), to detect a medium standardized effect (d = 0.50) on our primary outcome (self-reported PA) with a power of 0.80 and a two-tailed α less than 0.05, we needed 63 survivors per group. Although we maintained small to moderate effect sizes on our primary outcome (range: 0.18-0.38), the noticeable increase in variability (larger standard deviations, wider confidence intervals) in self-reported PA and walking at the 6-month follow-up time point compared with 3 months after randomization may partly explain why statistical significance was not achieved. Issues of power resulting from additional loss to follow-up may have also accounted for the failure to achieve statistical significance.

The results of other studies examining follow-up PAbehavior maintenance have been variable. Recently, Napolitano and colleagues (24) conducted a randomized controlled trial (the Women's Wellness Project) examining two print-based PA interventions in comparison with a contact control group in 280 sedentary women. At 3 months (i.e., postintervention), substantive differences in PA minutes per week favored the print interventions (a difference of 42 min·wk−1). At 12-month follow-up, there were no relevant differences between any of the group means (a difference of 11 min·wk−1). In another study, Bock and colleagues (1) compared motivationally matched PA PM against standard PA PM in 190 healthy men and healthy women. At 6 months (i.e., postintervention), participants receiving the motivation-matched PM reported significantly more PA minutes per week than those receiving the standard materials (a difference of 56 min·wk−1), again consistent with the magnitude of effect in our trial. These effects were maintained at the 6-month follow-up (a difference of 54 min·wk−1). Our results are consistent with those of Bock et al. and support the contention by Craig et al. (8) that written health information implemented in conjunction with self-monitoring devices and strategies (e.g., PED, tailored feedback reports) may result in greater PA behavior change and maintenance.

Perhaps most relevant to our study, Demark-Wahnefried and colleagues (10) examined the effects of a home-based diet and exercise program delivered via telephone counseling and PM in a mixed sample of 182 older breast and prostate cancer survivors (Project LEAD). The results show a trend towards higher PA in the intervention group during the 6-month intervention period, but they also show a trend toward higher PA in the comparison group at 6-month follow-up (i.e., 12 months after baseline). The disconnect between Project LEAD and our trial may be a result of the use of different self-report measures of PA (the LSI vs the CHAMPS), different theoretical models to develop intervention materials (the theory of planned behavior vs social cognitive theory and the transtheoretical model), our larger sample size (377 vs 182), our more homogeneous sample (breast cancer survivors vs breast and prostate combined), our focus on changing one behavior as opposed to two behaviors (PA vs PA and nutrition), and/or our younger sample (mean age = 58 vs 72 yr).

We found no statistically significant or meaningful differences between groups on HRQoL or fatigue at the 6-month follow-up time point. Comparing these results against those of other, distance-based PA interventions is difficult, given the lack of follow-up data pertaining to participant-rated outcomes (e.g., HRQoL, mood, self-esteem). The only other distance-based PA study in cancer survivors (10) reports findings similar to ours for the HRQoL (FACT-G) and physical functioning (SF-36 subscale) outcomes. The intervention group showed a trend towards higher scores after the 6-month intervention, but the effect had disappeared at 6-month follow-up. Carmack Taylor and colleagues (3) reported no changes in HRQoL in prostate cancer survivors at 6-month follow-up after a lifestyle PA program (Active for Life), although they also reported no effects at postintervention. Given that we previously have reported clinically relevant and meaningful improvements in both HRQoL and fatigue in the COM group (31), it is unlikely that a ceiling effect influenced our null findings on the HRQoL and fatigue variables.

We report a 71% participant-retention rate at the 6-month follow-up time point. Other distance-based trials have reported higher retention rates. Demark-Wahnefried and colleagues (10) retained 88% of participants in Project LEAD, and Napolitano and colleagues (24) (the Women's Wellness Project) reported 93% of participants retained. These higher retention rates may be attributable to the more intensive behavior change interventions implemented in these studies. For example, Project LEAD consisted of a series of 12, bimonthly, 20- to 30-min telephone sessions during a 6-month period; frequent communication with nutrition and PA counselors; and personalized workbooks. Furthermore, the Women's Wellness Project included face-to-face meetings with participants at both the 3-month and 12-month time points. Perhaps most comparable with our trial, Bock and colleagues (1) reported 77% of participants retained in their trial. This retention rate corroborates our reported 71%, likely because of the similarities in the designs of the respective studies. Specifically, Bock and colleagues (1) examined standard written PA material in comparison with stage-targeted written PA material with tailored feedback reports. The Bock et al. (1) study was also a distance-based trial in which participants were sent the intervention materials at one time immediately after randomization. It is important to reiterate that our trial consisted of a one-time mail-out after participants were randomized, and no contact was made with participants during the 6-month follow-up period. Future trials with limited contact during follow-up may need to consider other strategies to enhance follow-up completion rates.

At the 6-month follow-up time point, we reported that 38.5% (52/136) of survivors in the two groups that received PED as an intervention (COM and PED) continued to wear their PED during the 6-month follow-up period. During the 6-month follow-up period, participants were not specifically asked to wear the PED or to record their steps on a daily basis. Had participants been provided with supplementary tools, such as a step diary or step calendar, it is possible that more participants would have continued to wear their PED. The most frequently reported reason for not continuing to wear the PED was that participants forgot about, or lost, the PED (27%). Furthermore, a respectable 78.8% (N = 104) of survivors felt that the PED had helped them increase their PA behavior. Participants felt that the PED was motivating and encouraging (40%) and that it had provided them with information/awareness on how much PA they were doing (34%). Our findings corroborate those of Heesch and colleagues (15), who examined the experiences of 13 females who had previously participated in a PED-based intervention. Participants indicated that the PED had helped them increase awareness about their PA and set goals. It was also reported that the PED functioned as a motivator to increase PA. Researchers have speculated that PED may function as motivational tools to increase PA (12,28), PA-monitoring/measurement devices (13,27), and both (9,30). Our elicited data confirm the aforementioned research in that our participants perceived that the motivating nature and the immediate feedback provided were primarily responsible for their PA behavior. Future research needs to further explore the underlying mechanisms responsible for PA behavior change that is attributed to PED use.

The overall strengths of our trial have been noted elsewhere (31). Our trial is the first specifically in breast cancer survivors to examine longer-term follow-up of PA behavior and participant-rated outcomes. The low maintenance, inexpensive nature of the intervention materials (PM = $14.00 per participant (includes design costs); PED = $16.00 per participant), and the use of simple and practical intervention materials that can potentially affect a large number of breast cancer survivors, are further strengths of our study. The overall limitations of our trial have also been noted elsewhere (31). In particular, given that our sample was, on average, 39 months posttreatment, it is likely that some items on the FACT-B may no longer be relevant for longer-term breast cancer survivors (e.g., I have nausea). Therefore, other HRQoL scales may be more sensitive to detecting changes in HRQoL in long-term breast cancer survivors. Additional limitations of the present report include a 29% loss to follow-up at 6 months, failure to obtain objective PA data (i.e., step counts), and failure to obtain even longer-term follow-up (e.g., 1 yr). As indicated in Table 1, it was evident that survivors completing the 6-month follow-up time point (i.e., completers) were more likely to weigh less and be more active at baseline than those survivors who were lost-to-follow-up. Therefore, survivors who may benefit the most from relevant health behavior interventions may be more prone to terminating participation in such studies. Future research must consider these factors and examine ways of improving adherence rates across all participant profiles (e.g., behavioral, physical, physiological).

Our results suggest that PM and PED may have merit in promoting PA behavior maintenance at follow-up time points (e.g., 6-month follow-up). Although survivors did not maintain significantly higher PA or HRQoL at 6-month follow-up, the magnitude of the effect on PA (30-60 min·wk−1) was consistent with the immediate postintervention effect observed at the 3-month postintervention time point (31). Although it was evident that PA and brisk walking behavior decreased during the 6-month follow-up time point, survivors were still engaging in substantially more (and at a meaningful dose and intensity) PA and brisk walking than they reported at baseline. It seems that the use of user-friendly self-monitoring devices such as a PED, and targeted PM that is theoretically based, may enhance the likelihood of PA behavior maintenance. However, to prevent declines, researchers and practitioners should incorporate more interactive strategies (e.g., telephone calls, frequent mailings) during follow-up time points to encourage PA behavior that rivals (and perhaps improves) immediate postintervention levels. Further research should determine whether other, distance-based strategies are effective in assisting survivors in becoming more physically active. Given the motivated nature of our sample (e.g., reactive recruitment strategy, interested in increasing PA), future research needs to conduct similar trials with less motivated survivors. The distance-based option may complement clinic-based, supervised interventions that are not readily accessible to large numbers of cancer survivors. These types of interventions and programs can be implemented in most communities and may, consequently, benefit the greatest number of breast cancer survivors.

This study was supported by a research team grant from the National Cancer Institute of Canada (NCIC), with funds from the Canadian Cancer Society (CCS) and the CCS/NCIC Sociobehavioral Cancer Research Network. Jeffrey K. Vallance is now with the Center for Nursing and Health Studies at Athobasca University. At the time of this study, Jeffrey K. Vallance was supported by a Canada Graduate Scholarship from the Canadian Institutes of Health Research (CIHR) and a Doctoral Incentive Award from the Alberta Heritage Foundation for Medical Research (AHFMR). Kerry S. Courneya is supported by the Canada Research Chairs Program. Ronald C. Plotnikoff is supported by Salary Awards from CIHR and AHFMR. Irina Dinu is supported by a Postdoctoral Award from AHFMR.

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Keywords:

PHYSICAL ACTIVITY BEHAVIOR; QUALITY OF LIFE; HEALTH PROMOTION; PEDOMETERS

© 2008 American College of Sports Medicine

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