Although there is a higher prevalence of cardiovascular disease among women after age 45, women comprise only 34% of all coronary artery bypass graft (CABG) surgery population.1 Women experience more challenges to recovery after CABG surgery, as indicated by a slower and prolonged recovery. Slower recovery may be due to gender differences in preoperative health status; women tend to be older,2-6 have more comorbidities,2,3,6,7 and have more functional impairment.5,7-9 Women also are more likely to have urgent or emergent surgery compared with men.2,5,7 After surgery, women have a different symptom experience, including a slower resolution of symptoms and overall slower recovery after CABG surgery.4,5,10-12 Women experience a prolonged recovery, including a lag in regaining levels of baseline functioning and improvements in functioning after surgery when compared with men.5
Typically, despite known gender differences in recovery patterns, intervention studies to improve recovery after CABG surgery or other cardiac events have not been tailored specifically for women. In analyzing the data of a larger parent study, it seemed that women who had received the symptom management (SM) intervention had significantly lower symptom evaluation fatigue scores over time (at 3 and 6 weeks) and better physical activity scores (average kcal · kg−1 · d−1) over time (at 6 weeks and 3 months). Although the intervention of the parent study was not gender-specific, it was determined that a subset analysis should be conducted to determine the response of women-only to the early recovery SM intervention after CABG surgery. Therefore, this subset analysis of a larger randomized controlled trial specifically addressed the impact of an SM intervention on symptoms experienced at 6 weeks and physical functioning and physical activity at 6 weeks and 3 months among women, 65 years and older, who had undergone CABG surgery.
The specific aims of the study were as follows:
- To determine if there were differences in women who received the SM intervention compared with the routine care (RC) or control group on symptom evaluation scores (mean frequency and severity scores of 8 cardiac-related symptoms) at 6 weeks after CABG surgery
- To determine if there were differences in women who received the SM intervention compared with the RC group on physical functioning and physical activity variables (as measured by the RT3 accelerometer and an Activity Diary) in the early recovery period (6 weeks and 3 months) after CABG surgery
- To determine the relationship between symptoms experienced at 6 weeks and physical functioning and physical activity at 6 weeks and 3 months after CABG surgery
Several descriptive studies have documented that women have more symptoms, have a slower resolution of symptoms, and have an overall prolonged trajectory of recovery compared with men.4,5,10-13 In one study, at 1, 3, and 6 weeks after CABG surgery, women (n = 70) had significantly more physical symptoms than men (n = 187), with men having significantly greater decreases (P = .01) in symptoms over time.10 Women (n = 39) reported significantly (P < .05) more fatigue, shortness of breath (SOB), and angina compared with men (n = 112) at 6 months after surgery.11 Women had a higher prevalence of physical symptoms and greater ambulation dysfunction than men 3 and 6 weeks after CABG surgery.10 Women (n = 309) also experienced significantly (P < .002) more angina, dyspnea, and lack of appetite than men (n = 804) at 6 weeks after CABG surgery.5 Compared with men (n = 46), women (n = 19) consistently had higher symptom evaluation scores (impact of symptoms on physical activity) for SOB, fatigue, problems sleeping, swelling, and anxiety symptoms at 2, 4, and 6 weeks after CABG surgery.12
Physical Functioning and Physical Activity
Women experience a slower physical recovery than men after cardiac surgery. Vaccarino et al5 reported that women (n = 309) averaged a 13-point decline in Medical Outcomes Study Short Form-36 (MOS SF-36) physical functioning subscale scores after CABG surgery, whereas men (n = 804) had significantly less physical functioning change (P ≤.0001) between baseline and 6 to 8 weeks after surgery. Women's mean physical and vitality functioning subscale scores were consistently lower at 6 weeks and 3 months after surgery.12 At 6 months postsurgery, men's (n = 777) MOS SF-36 physical functioning scores were 3 times higher than women's (n = 295) scores (P ≤ .0001).14 Even at 3 months after CABG surgery, women (n = 60) were significantly (χ2 = 5.17, P = .02) less likely to have returned to their normal activities.9 Women also have more impaired functional capacity, also an indicator of physical functioning. In studies measuring functional capacity using the Duke Activity Status Index, female CABG surgical patients had significantly (P < .0001) poorer functional capacity, having lower preoperative (M = 21.5) scores compared with males (M = 32.2) and lower Duke Activity Status Index scores at 67,15 and 12 months15 after surgery.
In summary, women often experience differences in their recovery after CABG surgery. There have not been specific studies examining the types of cardiac surgery-related symptoms experienced by women and the relation of the symptoms experienced to other key outcomes of physical functioning and physical activity. This study contributes to the body of literature by examining women's responses to an intervention developed to improve SM and early recovery outcomes after CABG surgery.
Design and Sample
The design was a randomized, 2-group, repeated measures experimental study. Patients eligible to participate were randomly assigned by using a previously generated randomization schedule to either receive the SM intervention or receive RC only. A total of 280 subjects participated in the larger randomized controlled trial. A subsample derived from the 54 women who consented to participate in the randomized controlled trial (33 = SM, 21 = RC) was used in this subset analysis study. Nonparticipants among the sample of 54 was due to loss to follow-up from subject burden (n = 9), rehospitalization (n = 3), and equipment malfunction (n = 2). At the time this study was funded, awareness of intent-to-treat issues was not widespread among nursing researchers, and data collection (in whole or part) was not continued for those who dropped out or were dropped from the intervention. For this reason, it was not possible to conduct a strict intent-to-treat analysis. Therefore, a total of 40 women (SM group = 23, control group = 17) comprised the final subset of female subjects analyzed in this study.
The SM intervention was developed based on the major underlying assumptions that patient's specific knowledge, skills, self-efficacy, and expectations are needed to manage their symptoms and promote their physical functioning and physical activity after CABG surgery. For example, patients need to know how to assess symptoms (onset, location, duration, intensity, frequency), have the skill to monitor and record symptoms, have self-efficacy in their ability to monitor and record symptoms, and expect that their assessment will result in better management of their symptoms and related recovery outcomes. The SM intervention was delivered to the subjects using a Health Buddy device manufactured by Health Hero Network, which has been used to deliver disease management interventions.16 The Health Buddy is a small telehealth device that attaches to the telephone. In this study, "daily sessions" for 6 weeks (42 sessions) were delivered by the Health Buddy, providing algorithmic scripts designed to assess cardiac surgery-related symptoms (eg, fatigue and incision pain) and to provide strategies to assist the subjects in managing these symptoms. Self-efficacy enhancing communication techniques, based on Social Cognitive Theory,17 were used to frame the management strategies of the scripted daily sessions. Subjects responded to the assessments or other questions of the "daily" sessions, displayed on the Health Buddy screen, by pushing 1 of the 4 buttons. The subjects received further content based on their responses to the assessments. For example, a subject who rated his or her incision pain as a 10 on a "0" to "10" scale would receive more pain management strategies than one who rated incision pain as a "1." Responses to the daily sessions were downloaded to a secure Web site and were reviewed daily by the research nurse.
Demographic and patient characteristic tool collected information on pertinent variables to describe the sample.
Symptom Evaluation/Cardiac Symptom Survey (CSS). The CSS, developed by the research team,18 included 10 cardiac-related symptoms: angina, SOB, fatigue, depression, problems sleeping, incision pain, leg swelling, fluttering/rapid heart beats (palpitations), anxiety, and poor appetite. In this subset analysis, angina and fluttering symptoms will not be reported, as very few women experienced these 2 symptoms. On the CSS, symptom presence is first measured (the presence or absence of each symptom). Then subject indicated the frequency and severity of each reported symptom. Frequency and severity ratings of symptoms are evaluated on a "0" to "10" scale, with "0" indicating absence of the symptom and "10" indicating very frequent or very severe for each of the 10 symptoms. The scores for the 2 items (frequency and severity) are summed and divided by 2 resulting in a mean symptom evaluation score.
Content validity of the CSS was initially established based on questionnaires and interviews with both CABG patients and nurse researchers, as well as extensive literature reviews to determine pertinent symptoms to be included in the CSS and which symptom components to assess to best describe the symptom experience of CABG surgical patients. Further content validity (the relevance of each item to the domain of the postoperative CABG surgery patient symptom experience and clarity of the items) was confirmed by a panel of cardiovascular clinical nurse specialists.18 Internal consistency of each symptom evaluation score was supported in previous pilot data of females (n = 60) drawn from a population similar in demographic and clinical characteristics to the sample in this study, with alphas ranging from .76 to .97 at 2 weeks, from .83 to .99 at 4 weeks, and from .72 to .98 at 6 weeks after CABG surgery.
Physical functioning (MOS SF-36). Physical functioning of subjects was measured using 4 subscales comprising the physical component summary score of the MOS SF-36, version 2.0. The MOS SF-36 is a multidimensional scale measuring 8 aspects of functional status. In this study, the 4 subscales used were physical functioning (10 items), role limitations due to physical problems (4 items), bodily pain (2 items), and vitality functioning (4 items).19 Each concept is scored using standardized response choices on a scale of 0 to 100, with a higher score indicating better health or higher level of functional status. Reported internal consistency reliability alphas have ranged from .67 to .93.19-21 Cronbach alphas in this study sample for the physical, role physical, and bodily pain subscales ranged from .80 to .91 at 6 weeks and 3 months, whereas the vitality subscale alpha was .69 at both 6 weeks and 3 months after surgery.
Physical activity (RT3 accelerometer and Activity Diary). Physical activity was measured using the RT3® accelerometer (Stayhealthy, Inc) and an activity diary. Variables determined by the RT3 accelerometer were average activity counts/d and average kcal · kg−1 · d−1 expended. Diary variables included the average kcal · kg−1 · d−1 expended and average daily number of minutes spent exercising.
The RT3 is a triaxial accelerometer and registers body motion in the 3-dimensional space (anteroposterior axis, medial-lateral axis, and vertical axis). Counts of accelerations in the 3-dimensional axes are sampled every second and stored in a buffer, then the composite measure for all 3 axes are stored as vector magnitude (activity counts).22 The RT3 is considered 80% reliable in measuring activity when worn during a 3-day period.22 It is reliable in sedentary populations.23 Data were collected for 3 consecutive days (2 weekdays and 1 weekend day), and the average kcal · kg−1 · d−1 was computed.
A self-report Activity Diary included the number of minutes spent in each activity category: sleeping, light, moderate, hard, and very hard activity. These activity categories and equations to calculate kcal · kg−1 · d−1 were modeled after the Modified 7-Day Physical Activity Record.24 Type of exercise, duration (minutes), and distance (if appropriate) were recorded. The activity diary was completed for the same 3 days as the accelerometer. Average kcal · kg−1 · d−1 and average minutes spent exercising was computed based on the 3-day averages.
Institutional review board approval was obtained at the study site and sponsoring institutions. Participants were randomly assigned either to the SM intervention or control groups, after giving informed written consent. Demographic data were obtained from the medical record and subject interview. Subjects in the intervention group received instructions on how to use the Health Buddy and to connect the device to their home telephone before hospital discharge. The SM intervention group received daily sessions per Health Buddy for 6 weeks. Follow-up data on symptoms (CSS) and physical functioning (MOS SF-36) were collected by the research nurse at 6 weeks and 3 months after surgery via telephone interview.
The activity diaries and accelerometers were sent and returned via FEDEX. A letter specifying days the diary and accelerometer were to be used and an illustrated booklet indicating the correct accelerometer placement was included. Approximately 10% of the accelerometers were lost or not returned during the course of the parent study. Five women reported having some difficulty wearing the accelerometers, and 3 had trouble completing the activity diary.
Descriptive statistics were used to depict the subsample of women in this study. Significant nonnormality was exhibited by distributions of all symptom evaluation scores in both groups and by 2 of the 4 physical activity variables in at least 1 group, as indicated by high skewness or kurtosis or a significant Shapiro-Wilk test. Due to overall small sample size of women in this study, the nonparametric Mann-Whitney U test for differences was used for the first 2 aims. For the group sizes of this study, a 2-sided t test would have power >0.80 to detect a very large effect size (Cohen d = .95) at α = .05. The power of the Mann-Whitney U test is generally expected to be nearly as great, and sometimes greater, than that of the t test, depending on distributional characteristics.25 To determine the relationship between symptoms and physical activity and functioning, Spearman ρ correlation was used.
Sample Profile: The women in this subsample were an average age of 72.05 (±5.4) years. The majority was white (97.5%). There were no significant differences between the SM intervention or control groups by demographic or clinical variables (Table 1). Most of the subjects in the SM group (88%) completed at least 37 daily sessions or 90% of the intervention. The SM intervention delivered by the Health Buddy was found to be useful by 97% of the participants, and 88% were able to connect the device in less than 10 minutes to their home telephone.
Aim 1 was to determine if there were differences in women who received the SM intervention compared with the RC or control group on symptom evaluation scores (mean frequency and severity scores of 8 cardiac-related symptoms) at 6 weeks after CABG surgery. There was a significant difference in fatigue scores (by normal approximation, Z = 1.96, P ≤ .05) at 6 weeks. Women in the SM intervention group had less fatigue (M = 0.96), compared with the RC group (M = 2.47), as higher scores indicated more severity and/or frequency of the fatigue experienced. See Table 2 for mean and standard deviation scores on symptoms at 6 weeks after CABG surgery.
Although fatigue was the only symptom that showed significant differences at 6 weeks, there were other symptom evaluation scores that showed promise for the response to the intervention, particularly problems sleeping and depression. All of the other symptoms had lower mean scores for the intervention group at 6 weeks. However, with this small of a sample size and large standard deviations, caution must be taken when interpreting these results.
Symptoms were also measured at 3 months after surgery in the larger randomized controlled trial parent study. However, the small sample of women in this subset analysis, there were very few women in either group, SM intervention or control, who reported symptoms at 3 months; for example, there were only 7 female patients out of 40 who reported any swelling at 3 months after surgery (n = 4 in SM group, n = 3 in control group). Therefore, testing for difference on the small number of women reporting symptoms was not appropriate.
Aim 2 was to determine if there were differences in women who received the SM intervention compared with the control group on physical functioning and physical activity (RT3® accelerometer and diary) in the early recovery period (6 weeks and 3 months) after CABG surgery. There were no significant differences (P ≤ .05) by group on any of the physical functioning subscales of the MOS SF-36 (physical, role physical, vitality, or bodily pain) at 6 weeks or 3 months. However, women in the SM intervention group had a significantly higher average kcal · kg−1 · d−1 expended (Z = −1.71, P ≤ .05), which was a physical activity variable measured by the activity diary at 3 months after CABG surgery. Although the groups did not differ statistically at 6 weeks on this variable, the same trend in means existed. There were no statistically significant differences on the other 3 physical activity variables; however, the women in the intervention group were higher on 2 of these 3 variables measures at time of completion of the SM intervention (6 weeks) and at 3 months after CABG surgery. See Table 3 for means and standard deviations on all of the physical functioning and physical activity variables at both follow-up times by groups.
Aim 3 was to determine the relationship between symptoms experienced at 6 weeks and physical functioning and physical activity at 6 weeks and 3 months after CABG surgery. There were significant correlations between symptoms experienced at 6 weeks (SOB, fatigue, depression, incision pain, and problems sleeping) and physical functioning (physical, vitality, and bodily pain subscale scores) at both 6 weeks and 3 months, with correlations ranging from 0.31 to 0.46 (Table 4). The symptoms experienced at 6 weeks were moderately correlated, although not statistically significant, with vitality functioning at both times (6 weeks and 3 months) after surgery. Only the symptom of depression was significantly correlated (r = −0.34, P ≤ .05) with 1 physical activity variable, the mean kcal · kg−1 · d−1 expended at 3 months after CABG surgery.
There have not been other studies reporting the impact of interventions on postoperative symptoms and functioning of women after CABG surgery. Women clearly have a different recovery trajectory after CABG surgery than men. However, intervention studies to promote recovery after cardiac surgery and other cardiac interventions have not usually been gender-specific. This study examined only women, aged 65 years and older, who had undergone CABG surgery as well as how they responded to an SM intervention in the early recovery period after hospitalization. Findings from this study help to elucidate the usefulness of an SM intervention, given the known differences in recovery based on findings from previous research studies.
Others have reported that during the early recovery period (6 weeks after surgery), women consistently experience bothersome symptoms including SOB,5,12 angina, decreased appetite,5 fatigue, swelling, anxiety,12 and sleep and rest disturbances.10,12 Similarly, women in this study reported that fatigue, incision pain, problems sleeping, SOB, and depression were frequently occurring symptoms. These findings are also congruent with previous research reported by this research team.8,12,26,27
At time of surgery, women are more functionally impaired5,7-9 and slower to return to normal activities,5,9 with recovery delays persisting throughout the first year after surgery.15 Although there were no significant differences in physical functioning between the SM intervention and control groups of women, selected symptoms (fatigue, depression, problems sleeping, bodily pain) were significantly associated with their physical functioning and vitality. The MOS SF-36 subscales, generic measures of physical functioning, demonstrated the relationship between frequently occurring symptoms and physical functioning. These findings support the need to address cardiac-related symptoms to improve physical functioning and physical activity.
The study was limited by the small sample of female subjects, which decreased the statistical power. However, given that this was an exploratory subset analysis, the goal was not to find significant differences in all the variables.
Conclusion and Implications
Symptoms such as fatigue, sleep, depression, and pain are prevalent and persistent for women in the early recovery period after CABG surgery. In this study, fatigue was especially problematic for female CABG patients. Women in the SM intervention group were responsive to the intervention, as they had lower fatigue symptom evaluation ratings and engaged in more physical activity. Nurses are challenged to redesign biobehavioral interventions based on gender-specific responses of patients to cardiac events, such as older females recovering from CABG surgery. This subset analysis study supports the need for more targeted (women only) and tailored (eg, improving SM of fatigue and sleep) interventions to enhance physical activity and physical functioning outcomes after CABG surgery.
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