Background
Of all cancer types, breast cancer has the highest prevalence among women worldwide and is the leading cause of death [1]. In 2020, 2.3 million women were diagnosed with breast cancer, and 685,000 died globally [2]. In Korean women, it ranks first among all cancer types and is the fourth leading cause of death [3]. While breast cancer occurs later in life (> 70 years) in the United States, Australia, and the United Kingdom [4], an earlier onset, at approximately 40 years of age, has been reported in South Korea [4].
Treatment involves surgery complemented by chemo-, radiation, and hormone therapy to prevent the recurrence and metastasis of breast cancer cells [5]. Anti-hormone therapy is employed to suppress the female hormones that promote the growth of breast cancer cells by blocking their production or hindering their action [6]. Medications differ depending on whether it develops pre- or post-menopause [7], and they require long-term use (≥ 5 years).
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Medication nonadherence may arise, such as premature discontinuation of therapy or not using the prescribed dose at the correct time. A systematic review investigating five-year adherence rates to hormonal therapy among breast cancer patients reported an overall mean adherence rate of 66.2%. However, significant inter-country variations were observed, with rates of 71% in France, 57% in Italy, 58.5% in the United States, 80.1% in Ireland, and 63.1% in China [8]. While precise data for South Korea remains limited, a study of 136 breast cancer patients receiving hormonal therapy for 2.5 years revealed a high adherence rate in only 19.1% of participants [9]. Research on Korean breast cancer patients undergoing anti-hormonal therapy indicates that higher belief in anti-hormonal therapy and lower levels of depression and anxiety are associated with greater medication adherence [10]. Other factors such as age, social support from friends and healthcare providers, and experiences with medication side effects also play a role [11]. Since the implementation of the National Health Insurance system in 1989, all South Korean citizens have access to affordable healthcare, with significant government support for cancer treatment. However, the high number of patients seen by physicians often leads to brief consultations, potentially resulting in lower perceived psychosocial support [12]. Furthermore, post-surgical body image changes and the impact of chemotherapy can contribute to low self-esteem and depression among breast cancer patients, further affecting medication adherence [13]. As demonstrated by numerous previous studies, poor medication adherence significantly increases the risk of cancer recurrence and mortality [14]. Therefore, investigating the factors influencing medication adherence in breast cancer patients undergoing hormonal therapy is crucial.
Depression is a significant health concern for breast cancer survivors; it is a side effect of hormonal therapy, and it negatively impacts treatment continuation and prognosis [15]. Patients with breast cancer often experience psychological symptoms, such as fear of recurrence, diminished self-esteem, and depression, even after treatment [16]. The prevalence of depression is highest at diagnosis, with 50% experiencing depression within the first year after diagnosis, 25% at 2–4 years, and 15% at 5 years. Even after 5 years, approximately 8% continue to experience depression [17, 18].
Several scholars have proposed various models and theories to define empowerment. Spreitzer [19] emphasizes the role of intrinsic resources, highlighting autonomy, self-efficacy, meaning, and influence as key psychological factors enhancing empowerment. Conversely, Zimmerman [20] focuses on the interaction with the external environment, emphasizing the interplay of intrapersonal, interpersonal, and behavioral dimensions. This suggests that empowerment is not solely determined by individual characteristics or environmental factors but rather emerges from a dynamic interplay between internal psychological resources and active, effective engagement with the external environment. Consequently, for breast cancer patients, empowerment serves as a crucial element in fostering psychological well-being, promoting active treatment participation and adherence, ultimately facilitating successful disease management.
Empowerment refers to the acquisition of control over one’s own life and activities, overcoming feelings of powerlessness to gain a sense of autonomy and responsibility for one’s health [21]. It enhances intrinsic motivation [22]. Empowerment involves the desire to change one’s own behavior, encompassing the motivation to alter and amend self-care practices, and it reduces barriers to medication adherence [23]. While patients previously adhered only to doctors’ orders for health management, the emphasis is now on active patient participation and decision-making in the diagnostic and treatment process, emphasizing self-management [24, 25]. Having control over the treatment process and managing self-care practices makes empowerment significantly meaningful for patients with breast cancer [26], and it should be used to encourage medication adherence. Particularly for Korean women, the traditionally male-centered social structure and cultural characteristics can lead to low levels of empowerment in managing their own health [27]. In Korean society, women’s roles and responsibilities within the family are still prominent, which can result in tendencies to neglect their own self-care. Additionally, stereotypes regarding gender roles in the healthcare environment continue to exist, making it difficult for women to make autonomous decisions regarding their health.
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Several factors can influence empowerment, including support from health providers, patient characteristics, health literacy, and self-management [28]. Empowerment not only fosters better health outcomes, including improved medication adherence [29, 30], but can also reduce the psychological distress associated with cancer treatment [31]. Nonetheless, healthcare systems often face challenges in promoting empowerment, such as time constraints, limited resources, and difficulties in effective communication with patients [32, 33].
Study purpose
We aimed to determine the impact of depression and empowerment on medication adherence in patients undergoing anti-hormonal therapy for breast cancer, provide foundational data for the development of effective nursing interventions, and aid in improving medication adherence by determining the relationship between these factors.
Methods
Design
Descriptive research serves as a foundational inquiry method that seeks to gather information about specific phenomena by examining key factors such as health characteristics, behaviors, and attitudes [34]. Considering this, the current study employs a descriptive survey design to explore the influence of various factors including sociodemographic characteristics, medical history and status, treatment and experience, depression, and empowerment on medication adherence among breast cancer patients.
The research specifically addresses the following question: “What is the impact of depression and empowerment on medication adherence in breast cancer patients undergoing hormone therapy?” To illustrate the relationships among these variables, the conceptual model of this study is presented in Fig. 1.
Fig. 1
Conceptual model
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Ethics approval and consent to participants
Prior to data collection, participants were given a detailed explanation of the study’s purpose and content as well as assurances of anonymity and protection of personal information. It was emphasized that the collected data would remain confidential and be used solely for research purposes. Participants were informed that they could withdraw from the study at any time if they did not wish to continue. Informed consent was obtained from all participants before proceeding with data collection. To protect participants’ information, completed questionnaires were assigned individual numbers to ensure personal data could not be identified, and were then used for data analysis. The ethical aspects of the study were prioritized, and the study was conducted after receiving approval from the Wonkwang University Hospital Institutional Review Board (IRB NO. WKUH-2022-05-043).
Data collection
Data were collected through surveys conducted among outpatients between July 1 and August 31, 2022 using convenience sampling. To eliminate self-report bias, questions related to participants’ personal information were removed, and the surveys were conducted in a private space where confidentiality was ensured. Additionally, questionnaires were distributed in advance to three patients aged 50–70 to assess their understanding of the items. Before data collection began, potential difficulties in responding to the surveys, the time required, and the appropriateness of the survey method were verified. The participants were breast cancer patients at Wonkwang University Hospital in I City, South Korea, who had undergone surgery, radiation therapy, or chemotherapy and had initiated adjuvant drug therapy at least 6 months prior. Wonkwang University Hospital was selected as the study site due to its status as a tertiary hospital in South Korea, serving a large number of breast cancer patients and thus providing a readily accessible and diverse patient population for sample recruitment. The sample size was determined using G*Power 3.1 [35], a sample size calculation program based on Cohen’s formula. Setting the significance level (α) at 0.05, power at 0.90, effect size at 0.15, and the number of predictor variables at 16, the minimum required sample size was calculated to be 175. To account for an anticipated dropout rate of 20%, 200 questionnaires were distributed, with 183 being used in the final analysis.
Based on previous research [36‐38], the specific inclusion and exclusion criteria were established as follows:
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Inclusion Criteria:
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Individuals who had been diagnosed with breast cancer and had been receiving anti-hormonal therapy for > 6 months.
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Participants who were aware of their cancer diagnosis.
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Individuals without cognitive impairment and who were able to communicate and respond to the questionnaire.
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Individuals who understood the purpose of the research and consented to participate.
Exclusion Criteria:
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Patients who had completed courses of anti-hormonal therapy following breast cancer diagnosis.
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Individuals who were diagnosed with any cancer other than breast cancer.
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Variables
The measurement tool for this study was a self-report questionnaire comprising 77 items: 14 questions on general characteristics, 12 on medication adherence, 21 on depression, and 30 on empowerment.
General characteristics
This section included 14 questions covering age, marital status, educational level, occupation, monthly income, age at diagnosis, type of surgery, time elapsed since surgery, experience with adjuvant therapy, comorbidities, medications taken, timing of medication intake, medication side effects, and health status.
Medication adherence
This study used the Korean version of the Adherence to Refills and Medication Scale (ARMS) adapted by Kim et al. [38] from that developed by Kripalani et al. [39]. This tool consists of 12 items, including eight assessing the intention to adhere to medication and four evaluating the willingness to obtain refills. It employs a 4-point Likert scale, scored as follows: “Not at all” = 1, “Sometimes” = 2, “Often” = 3, and “Always” = 4. The scores ranged from 12 to 48, with scores of 16 or below indicating higher medication adherence, while scores above 16 indicated lower adherence [40]. The reliability of the ARMS at the time of development by Kripalani et al. [39] had a Cronbach’s α = 0.81, while in the study by Kim et al. [38] Cronbach’s α = 0.80, and in this study, Cronbach’s α = 0.91.
Depression
Depression was measured using the Korean version of the Beck Depression Inventory-II (BDI-II) adapted by Sung et al. [41], using the scale developed by Beck et al. [42]. The BDI-II is a self-reported scale developed to measure the presence and severity of depression in adults. It comprises 21 items that assess the emotional, psychological, and physical symptoms of depression. Each item is measured on a 0–3-point Likert scale. The score range is 0–63 points, with higher scores indicating more severe depressive symptoms. Beck et al. [42] categorized depression severity into four levels based on depression scores: 0–13 indicating normal, 14–19 mild, 20–28 moderate, and 2–-63 severe depression. The Cronbach’s α, indicating the reliability of the tool at the time of its development was 0.92 [42], that of the adapted Korean version was 0.83 [41], and in this study, it was 0.86.
Empowerment
Empowerment was measured using the tool developed by Shin and Park [26] for women with breast cancer. Developed to facilitate breast cancer patients’ understanding of their strengths and weaknesses in health self-management, this instrument was refined through in-depth interviews with 10 patients, expert content validation (n = 12), and confirmatory factor analysis to ensure structural validity. It consists of 30 items: 14 on internal factors, eight on interactional factors, and eight on behavioral factors across three sub-areas. Internal factors include statements such as “I can overcome the crisis that I face” and “I try to overcome physical changes that occurred due to breast cancer.” Interactional factors are reflected in items like “I confidently tell my family what I want and what I do not want” and “I am obtaining beneficial information from those who suffered from breast cancer.” Finally, behavioral factors are represented by statements such as “I actively participate in my treatment process” and “I actively search for information to acquire knowledge on breast cancer.” Each item is measured on a 5-point Likert scale ranging from “very true” (5 points) to “not true at all” (1 point). The score range is 30–150, with the total score representing the level of empowerment; the higher the score, the greater the level of empowerment. The Cronbach’s α, indicating the reliability of the tool at the time of its development by Shin and Park [26] was 0.95, and in this study, it was 0.96.
Data analysis
Data were analyzed using SPSS version 26.0 (IBM Corp, Armonk, NY, USA). The general characteristics of the participants, medication adherence, depression, and empowerment were analyzed in terms of frequency, percentage, mean, and standard deviation. Differences in adherence, depression, and empowerment were assessed using the t-test and analysis of variance, with post-hoc analysis conducted using the Scheffé test. Correlations between adherence, depression, and empowerment among the participants were analyzed using Pearson’s correlation coefficients. In the final step, hierarchical regression analysis was used to examine the impact of depression and empowerment on medication adherence in breast cancer patients, after controlling for general characteristics such as age, level of education, occupation, adjunctive therapy, and subjective health status, which were identified as influencing factors.
Results
General characteristics
The general characteristics of the participants are presented in Table 1. The age group with the largest proportion was participants in their 50s, comprising 68 individuals (37.2%), and those with a spouse accounted for 151 individuals (82.5%). The highest level of education attained by most participants was high school graduation (36.6%), and approximately half of the participants (53%) were unemployed. The time of diagnosis for breast cancer was most often between 1 and 3 years, followed by a period between 3 and 5 years. Partial resection was the predominant surgery type, involving 127 patients (69.4%), which was higher than that for total mastectomy. The most common postoperative period was between 1 and 3 years, and the group with the most experience in adjuvant therapies comprised 84 individuals (45.9%) who only received radiation therapy. Those with comorbidities accounted for 50.8%, which was higher than the percentage of those without comorbidities. Tamoxifen was the most frequently prescribed medication. The longest duration of anti-hormone therapy intake was between 1 and 3 years (68 individuals (37.2%). A total of 115 patients (62.8%) reported experiencing side effects from anti-hormonal medications. The primary side effects included muscle pain, nausea, and edema. In terms of subjective health status, 99 individuals (54.1%) reported feeling unwell, 60 (32.8%) reported feeling average, and 24 (13.1%) reported feeling well.
Table 1
General characteristics of the participants (N = 183)
Characteristics | Categories | N | % | M ± SD |
|---|---|---|---|---|
Age | 30–39 years | 6 | 3.3 | 57.14 ± 10.26 |
40–49 years | 37 | 20.1 | ||
50–59 years | 68 | 37.2 | ||
60–69 years | 42 | 23.0 | ||
≥ 70 years | 30 | 16.4 | ||
Spousal Status | With spouse | 151 | 82.5 | |
Without spouse | 32 | 17.5 | ||
Educational level | Elementary school or less | 26 | 14.2 | |
Middle school | 31 | 16.9 | ||
High school | 67 | 36.6 | ||
College or higher | 59 | 32.3 | ||
Occupation | Yes | 86 | 47.0 | |
No | 97 | 53.0 | ||
Time of Diagnosis | 6 months–1 year | 19 | 10.4 | |
1–3 years | 81 | 44.3 | ||
3–5 years | 53 | 29.0 | ||
≥ 5 years | 30 | 16.3 | ||
Type of Surgery | Partial resection | 127 | 69.4 | |
Total resection | 56 | 30.6 | ||
Post-surgical period | 6 months–1 year | 20 | 10.9 | |
1–3 years | 84 | 45.9 | ||
3–5 years | 51 | 27.9 | ||
≥ 5 years | 28 | 15.3 | ||
Experience with Adjunctive Therapy | Radiation | 84 | 45.9 | |
Chemotherapy | 28 | 15.3 | ||
Radiation + Chemotherapy | 71 | 38.8 | ||
Presence of Comorbidities | Yes | 93 | 50.8 | |
No | 90 | 49.2 | ||
Current Medication | Tamoxifen | 94 | 51.4 | |
Arimidex | 44 | 24.0 | ||
Femara | 34 | 18.6 | ||
Tamoxifen + Femara | 11 | 6.0 | ||
Duration of Medication Use | 6 months–1 year | 48 | 26.2 | |
1–3 years | 68 | 37.2 | ||
3–5 years | 43 | 23.5 | ||
≥ 5 years | 24 | 13.1 | ||
Side effects of anti-hormone | Present | 115 | 62.8 | |
Absent | 68 | 37.2 | ||
Subjective health status | Good | 24 | 13.1 | |
Moderate | 60 | 32.8 | ||
Bad | 99 | 54.1 |
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Participants’ medication adherence, depression, and empowerment
The participants’ scores for adherence, depression, and empowerment are presented in Table 2. The mean medication adherence score was 41.94, with a mean rating of 3.50. The participants had an average depression score of 19.67, and over half reported moderate or severe depressive symptoms. Approximately 33.9% of participants stated that they did not experience any depression. The participants had an average empowerment score of 106.40, with the interpersonal factor in the lower subdomain having an average score of 50.65 and the highest mean rating of 3.62.
Table 2
Participants’ medication adherence, depression, and empowerment (N = 183)
Variables | N(%) | M ± SD | Score range | Average rating |
|---|---|---|---|---|
Medication adherence | 18.06 ± 5.15 | 12–48 | 1.50 ± 0.43 | |
Non-adherent (≥ 16) | 107(58.5) | |||
Adherent (< 16) | 76(41.5) | |||
Depression | 19.67 ± 11.25 | 0–63 | ||
None | 63(33.9) | 7.34 ± 3.85 | 0–13 | |
Mild | 32(16.9) | 16.16 ± 1.86 | 14–19 | |
Moderate | 47(27.3) | 24.26 ± 2.44 | 20–28 | |
Severe | 41(21.9) | 35.34 ± 5.23 | 29–63 | |
Empowerment | 106.40 ± 18.15 | 66–150 | 3.55 ± 0.61 | |
Intrapersonal factor | 50.65 ± 9.35 | 29–70 | 3.62 ± 0.67 | |
Interactional factor | 28.39 ± 5.14 | 16–40 | 3.55 ± 0.64 | |
Behavioral factor | 27.36 ± 5.51 | 16–40 | 3.42 ± 0.69 |
Differences in medication adherence based on general characteristics
The results of the analysis of medication adherence based on the general characteristics of the patients are presented in Table 3. Significant differences in medication adherence were observed across age groups (F = 8.027, p < .001). The mean adherence score was 13.17 ± 2.04 for the 30–39 age group, 19.36 ± 4.61 for the 60–69 age group, and 21.23 ± 6.41 for those aged 70 and older. Post-hoc analysis revealed significantly higher adherence in the 30–39 age group compared to the 60–69 and ≥ 70 age groups. Education level also significantly impacted adherence (F = 8.444, p < .001). The mean adherence score was 20.81 ± 5.16 for those with an elementary school education or less, 18.19 ± 5.40 for those with a middle school education, and 15.78 ± 3.25 for those with a college education or higher. Post-hoc tests indicated significantly higher adherence in the college-educated group compared to those with elementary and middle school education levels. Adherence was better among individuals with employment than among those without (t= -5.207, p < .001). There was a statistically significant difference in adherence based on experience with adjunctive therapy (F = 3.672, p = .027); however, post-hoc tests revealed no significant differences. Medication adherence also differed significantly based on self-reported subjective health status (F = 11.729, p < .001). The mean adherence scores were 15.54 ± 4.01 for those reporting good health, 16.45 ± 4.38 for those reporting moderate health, and 19.65 ± 5.32 for those reporting bad health. Post-hoc analyses showed significantly better adherence among those reporting good or moderate health compared to those reporting bad health.
Table 3
Medication adherence depending on general characteristics
Characteristics | Cathegories | M ± SD | F or t | p | Scheffé |
|---|---|---|---|---|---|
Age | 30–39 years a | 13.17 ± 2.04 | 8.027*** | < 0.001 | a<.d, e |
40–49 years b | 15.70 ± 3.48 | ||||
50–59 years c | 17.57 ± 4.84 | ||||
60–69 years d | 19.36 ± 4.61 | ||||
≥ 70 years e | 21.23 ± 6.41 | ||||
Spousal Status | With spouse | 17.93 ± 4.94 | − 0.659 | 0.513 | |
Without spouse | 18.69 ± 6.11 | ||||
Educational level | Elementary school or less a | 20.81 ± 5.16 | 8.444*** | < 0.001 | d<.a, b |
Middle school b | 19.81 ± 5.85 | ||||
High school c | 18.19 ± 5.40 | ||||
College or higher d | 15.78 ± 3.25 | ||||
Occupation | Yes | 16.14 ± 3.45 | -5.207*** | < 0.001 | |
No | 19.76 ± 5.79 | ||||
Time of Diagnosis | 6 months–1 year | 17.84 ± 4.89 | 1.093 | 0.353 | |
1–3 years | 17.42 ± 5.43 | ||||
3–5 years | 18.42 ± 4.72 | ||||
≥ 5 years | 19.30 ± 5.24 | ||||
Type of Surgery | Partial resection | 17.57 ± 4.95 | -1.966 | 0.051 | |
Total resection | 19.18 ± 5.47 | ||||
Post-surgical period | 6 months–1 year | 17.75 ± 4.83 | 1.283 | 0.282 | |
1–3 years | 17.34 ± 5.40 | ||||
3–5 years | 18.80 ± 4.69 | ||||
≥ 5 years | 19.07 ± 5.34 | ||||
Experience with Adjunctive therapy | Radiation | 18.94 ± 5.57 | 3.672* | 0.027 | |
Chemotherapy | 18.64 ± 5.19 | ||||
Radiation + Chemotherapy | 16.79 ± 4.38 | ||||
Presence of Comorbidities | Yes | 18.78 ± 5.87 | 1.960 | 0.052 | |
No | 17.31 ± 4.19 | ||||
Current Medication | Tamoxifen | 17.73 ± 5.02 | 1.886 | 0.134 | |
Arimidex | 17.77 ± 5.31 | ||||
Femara | 18.21 ± 4.78 | ||||
Tamoxifen + Femara | 21.55 ± 6.09 | ||||
Duration of Medication Use | 6 months–1 year | 17.90 ± 5.76 | 0.567 | 0.637 | |
1–3 years | 17.56 ± 4.94 | ||||
3–5 years | 18.60 ± 4.96 | ||||
≥ 5 years | 18.83 ± 4.95 | ||||
Side Effects of Anti-Hormone | Present | 18.43 ± 5.43 | 1.282 | 0.202 | |
Absent | 17.43 ± 4.61 | ||||
Subjective Health Status | Good a | 15.54 ± 4.01 | 11.729*** | < 0.001 | a, b <.c |
Moderate b | 16.45 ± 4.38 | ||||
Bad c | 19.65 ± 5.32 |
Correlation between medication adherence, depression, and empowerment
The correlation results among medical adherence, depression, and empowerment are as follows (Table 4). The correlation coefficient between depression and medication adherence (r = .537***, p < .001) indicates a positive correlation between the two variables, suggesting that as depression increases, medication adherence also tends to increase statistically. The positive correlation between severe depression and medication adherence (r = .463***, p < .001) indicates that patients with severe depression may have a higher likelihood of receiving additional support, which can lead to better medication adherence. Conversely, the correlation between severe depression and empowerment (r=-.552***, p < .001) demonstrates a strong negative association, suggesting that patients with severe depression are likely to have lower levels of empowerment. The correlation coefficient between depression and empowerment (r=-.696***, p < .001) shows a strong negative correlation, indicating that as depression increases, levels of empowerment tend to decrease. This suggests that enhancing emotional support and empowerment may be crucial for improving patient outcomes. The correlation coefficient between medication adherence and empowerment (r=-.705***, p < .001) indicates a strong negative correlation, which suggests that as medication adherence increases, the level of patient empowerment may decrease.
Table 4
Correlation of independent variables
Medication adherence | Empowerment | |
|---|---|---|
r(p) | ||
Depression | 0.537*** (< 0.001) | − 0.696*** (< 0.001) |
Mild | − 0.031 (0.681) | − 0.017 (0.823) |
Moderate | 0.013 (0.866) | − 0.070 (0.343) |
Severe | 0.463*** (< 0.001) | − 0.552*** (< 0.001) |
Medication adherence | 1 | − 0.705*** (< 0.001) |
Factors influencing medication adherence
Hierarchical regression analysis was conducted to identify factors influencing medication adherence among participants (Table 5). The regression model showed significant results in Model 1 (F = 10.852, p < .001), Model 2 (F = 10.177, p < .001), and Model 3 (F = 16.769, p < .001) indicating the statistical significance of the model. The explanatory power of the regression model was 36.1% (R2 = 0.361, adj R2 = 32.8%) in Model 1, increased steadily to 41.8% (R2 = 0.418 adj R2 = 37.7%) in Model 2, and increased sharply to 60.1% (R2 = 0.601 adj R2 = 56.5%) in Model 3. Furthermore, the Durbin–Watson statistic of 1.744, approximately approaching a value of 2, suggests that there were no issues with the assumption of independence of residuals. Additionally, the variance inflation factor was < 10 for all variables, indicating no multicollinearity problems.
Table 5
Hierarchical linear model
Variables | Categories | Model 1 | Model 2 | Model 3 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
B | β | t | p | B | β | t | p | B | β | t | p | ||
(constant) | 11.449 | 4.023 | < 0.001 | 11.012 | 4.001 | < 0.001 | 32.131 | 9.387 | < 0.001 | ||||
age | 0.115 | 0.229 | 2.996** | 0.003 | 0.099 | 0.197 | 2.645** | 0.009 | 0.066 | 0.132 | 2.105* | 0.037 | |
Education level (ref = elementary school) | Middle school | − 0.346 | − 0.025 | − 0.304 | 0.761 | − 0.638 | − 0.047 | − 0.579 | 0.563 | − 0.820 | − 0.060 | − 0.882 | 0.379 |
High school | − 0.441 | − 0.041 | − 0.409 | 0.683 | 0.041 | 0.004 | 0.039 | 0.969 | 0.189 | 0.018 | 0.212 | 0.832 | |
University or higher | -2.790 | − 0.254 | -2.446* | 0.015 | -2.152 | − 0.196 | -1.918 | 0.057 | -1.073 | − 0.098 | -1.096 | 0.274 | |
Occupation (ref = Absent) | present | -1.781 | − 0.173 | -2.533* | 0.012 | -1.344 | − 0.131 | -1.939 | 0.054 | -1.205 | − 0.117 | -2.077* | 0.039 |
Adjunctive therapy (ref = Radiation) | Chemotherapy | − 0.007 | 0.000 | − 0.007 | 0.994 | 0.429 | 0.030 | 0.465 | 0.642 | − 0.043 | − 0.003 | − 0.055 | 0.956 |
Radiation + Chemo | − 0.997 | − 0.095 | -1.396 | 0.165 | − 0.864 | − 0.082 | -1.251 | 0.213 | − 0.928 | − 0.088 | -1.607 | 0.110 | |
Subjective health status (ref = Good) | Moderate | 0.743 | 0.068 | 0.714 | 0.476 | 0.307 | 0.028 | 0.298 | 0.766 | − 0.117 | − 0.011 | − 0.136 | 0.892 |
Bad | 3.966 | 0.385 | 4.040*** | < 0.001 | 2.630 | 0.255 | 2.541* | 0.012 | 1.697 | 0.165 | 1.942 | 0.054 | |
Depression (ref = None) | Mild | 2.237 | 0.165 | 2.395* | 0.018 | − 0.289 | − 0.021 | − 0.347 | 0.729 | ||||
Moderate | 1.187 | 0.101 | 1.369 | 0.173 | − 0.468 | − 0.040 | − 0.611 | 0.542 | |||||
Severe | 3.856 | 0.313 | 3.787*** | < 0.001 | − 0.404 | − 0.033 | − 0.405 | 0.686 | |||||
Empowerment | Intrapersonal factor | − 0.249 | − 0.451 | -5.165*** | < 0.001 | ||||||||
Interactional factor | 0.088 | 0.094 | 1.139 | 0.256 | |||||||||
Behavioral factor | − 0.245 | − 0.244 | -2.685** | 0.008 | |||||||||
F | 10.852(p < .001) | 10.177(p < .001) | 16.769(p < .001) | ||||||||||
R2 | 0.361 | 0.418 | 0.601 | ||||||||||
adj R2 | 0.328 | 0.377 | 0.565 | ||||||||||
R-squared change | 0.361 | 0.057 | 0.240 | ||||||||||
The analysis results, after treating education level, occupation, adjunctive therapy, and subjective health status as dummy variables, indicated that adherence decreased as age increased (β = 0.229, p = .003). Moreover, individuals with an elementary school education tended to have lower adherence than university graduates (β=-0.254, p = .015). Additionally, adherence was lower when participants did not have an occupation than when they did (β=-0.173, p = .012). Finally, participants who reported bad subjective health status (β = 3.966, p = < 0.001) exhibited lower adherence than those who perceived their health as better.
In Step 2, after adding the variable of depression level, it was found that age (β = 0.197, p = .009) and bad subjective health status (β = 0.255, p = .012) influenced medication adherence. Additionally, both the mild (β = 0.165, p = .018) and severe (β = 0.313, p = < 0.001) depression groups had an impact on medication adherence.
In Step 3, age was found to have a significant positive influence (β = 2.105, p = .037), while having an occupation (β=-0.117, p = .039) and the subdomains of empowerment, intrapersonal factors (β=-0.451, p = < 0.001), and behavioral factors (β=-2.685, p = .008) showed significant negative influences on adherence. Specifically, younger age, having an occupation, and higher levels of empowerment subdomains positively influenced adherence.
Discussion
This study identifies depression and empowerment as key independent variables influencing medication adherence in female breast cancer patients, based on findings from previous research. Studies have reported that depression and empowerment in women with breast cancer can be influenced by cultural factors in different countries. For instance, in Ghana, breast cancer is believed to stem from an immoral lifestyle [43], while in Iran and Malaysia, it is perceived as resulting from a divine curse or evil forces [44, 45]. These misconceptions and beliefs have been shown to negatively impact women’s treatment rates for the disease. Notably, the mortality rate for breast cancer patients in these countries is relatively higher compared to others [46]. This can be attributed to the societal stigma that induces feelings of depression even after diagnosis, making cancer prevention and early detection challenging [47]. Empowerment, which involves enhancing confidence and self-efficacy regarding the disease, leads to health-promoting behaviors such as adherence to medication. It is described as a process where one feels inner strength through relationships with family, friends, and healthcare professionals [48]. However, empowerment is also heavily influenced by strong cultural beliefs and faith, which can limit access to education and information [49]. Therefore, it is crucial to consider how cultural factors and contexts affect depression and empowerment in breast cancer patients, as these can delay mental health and disease recovery processes. Designing personalized support and treatment approaches is essential, allowing for the development of tailored strategies that respect each patient’s cultural background and personal beliefs while achieving optimal treatment outcomes.
The correlation analysis of the variables in this study revealed a positive correlation between depression and medication adherence, while a negative correlation was found between empowerment and medication adherence. Specifically, as depression scores decreased and empowerment increased, the medication adherence of breast cancer patients also improved. Depression is considered a common psychological disorder among breast cancer patients, representing an adjustment disorder during the disease process [50]. Among the participants in this study, 49.2% reported moderate to severe depression. Furthermore, when analyzing the impact of depression as an independent variable on medication adherence in Model 2, it was observed that higher severity of depression was associated with lower adherence to medication. Based on these findings, it is crucial to emphasize the importance of early intervention. Specifically, effective management of depression from the early treatment stages of breast cancer is essential. Therefore, regular depression screening and early intervention are required for all breast cancer patients, with particularly thorough management needed for those suffering from severe depression. Various methods for early intervention may be applicable, including cognitive-behavioral therapy, group therapy, individual counseling, and pharmacotherapy all of which may serve as effective approaches [51‐53]. Such interventions can assist patients in addressing their emotional issues and motivate them to adhere to their medication regimen. Additionally, ongoing monitoring and counseling support should be maintained throughout the treatment period. However, empowerment is a critical factor that enables individuals to feel autonomy and responsibility regarding their health and to overcome feelings of helplessness. Negative emotions, such as depression, diminish empowerment, and therefore, empowerment strategies aimed at reducing these negative feelings and enhancing self-management capabilities should be regarded as essential for improving medication adherence among breast cancer patients. If depression can be effectively managed through early intervention, it is believed that patients will ultimately be able to adhere better to their medication regimen, thereby improving treatment outcomes.
The results of Model 1 indicate that age, education level, employment status, and subjective health significantly influence medication adherence. Specifically, younger age, higher education levels, having a job, and perceiving one’s health status as good were associated with higher levels of medication adherence. In the study by Jung and Lim [10], the average age of participants was 50.81 years, with a medication adherence score of 16.19 [34]. Additionally, Hartch et al. [54] reported an average age of 49 years and a medication adherence score of 17.5. In contrast, the medication adherence score in this study was 18.06, which is relatively high compared to previous research, likely due to the higher average age of participants in this study (57.14 years). Consequently, it can be inferred that the level of medication adherence is not as low as suggested by other studies. Several prior studies highlight a positive correlation between age and empowerment [55, 56]. Specifically, it has been reported that empowerment tends to increase with age. The correlation analysis in this study also revealed that greater empowerment was associated with higher medication adherence. This suggests that older participants with higher empowerment levels are likely to have better medication adherence. However, factors influencing empowerment are multifaceted, as noted in various studies, which have identified personal social and cultural contexts, as well as past experiences, as significant influences. Therefore, further research is required to understand the relationship between age and medication adherence. In summary, according to Lomper et al. [41], increases in age may lead to declines in cognitive function and agility, which could potentially reduce medication adherence [57]. Conversely, patients with higher education levels tend to have a greater awareness of the importance of medication adherence, leading to improved adherence. These factors collectively suggest that medication adherence is influenced by a complex interplay of various elements, warranting deeper exploration of these relationships in future studies.
Employment status also influenced medication adherence and was closely associated with economic status. Previous studies have shown that groups with employment and higher monthly incomes have higher adherence scores [58]. This aligns with the idea that economic vulnerability can lead to lower adherence rates due to financial burdens. Moreover, subjective health status affects adherence in patients with breast cancer. A study investigating factors affecting adherence in patients undergoing hemodialysis also found that a higher perceived subjective health status was associated with better adherence [59]. Subjective health status involves a comprehensive evaluation of one’s health in terms of physical, physiological, psychological, and social aspects [60], and it is a precursor to adherence [61]. A higher perceived subjective health status leads to a more proactive approach toward health management and health promotion behaviors, as it reduces negative perceptions such as anxiety, depression, or cancer stigma [62]. Therefore, efforts are needed to improve adherence in patients with breast cancer who require long-term hormonal therapy, with a focus on supporting older adults and economically vulnerable individuals.
This study’s findings confirm that Model 3 shows the impacts of age, employment status, and empowerment on the medication adherence of breast cancer patients. Notably, age and employment status emerged as significant factors influencing medication adherence, while the main independent variable, empowerment, also played a crucial role through its personal and behavioral factors. Empowerment is defined as a positive concept that allows patients to feel autonomy and responsibility concerning their health and to overcome feelings of helplessness [21, 63]. It consists of personal internal, interactive, and behavioral factors [26]. The findings indicate that both personal and behavioral factors were influential, but personal factors had a more substantial impact. Personal internal factors include the acceptance of femininity, self-determination, self-control, and self-efficacy. Hunter et al. [64] highlighted that an individual’s confidence, self-esteem, and autonomy are key elements in enhancing women’s empowerment. In other words, the greater the confidence in one’s ability to cope positively with difficult situations, the higher the level of empowerment. Behavioral factors encompass actions related to organizational participation, information seeking, and practices for self-management. This study demonstrated that actively accepting the loss of femininity due to breast cancer and engaging in self-management activities proved more effective than merely seeking support from others to solve problems. This finding aligns with prior research, which showed that personal factors improved self-determination and control [26], and that behavioral empowerment promoted health-enhancing behaviors [65]. Therefore, for breast cancer patients undergoing long-term hormonal therapy, personal and behavioral factors related to empowerment are essential for effective health management and maintenance.
Medication adherence requires that patients develop the intention to act, which necessitates the prior enhancement of personal factors such as confidence and self-efficacy [66]. To enhance medication adherence among breast cancer patients, it is essential to implement nursing strategies that assess and intervene in empowerment. Specifically, program development is necessary to simultaneously improve personal internal and behavioral factors. In hospitals, empowerment can be enhanced through programs that focus on strengthening patients’ internal confidence and self-efficacy to boost their intention to adhere to medication. This could include comprehensive approaches such as regular educational sessions, support groups, digital reminder services, and psychological counseling. Such integrated support can help patients actively participate in their treatment process and maintain consistent medication adherence.
This study has some limitations. Dependence on self-reported data introduces biases that could skew the results, particularly in relation to empowerment scores. Participants may feel pressured to provide socially desirable responses, which could inflate their self-reported levels of empowerment and potentially misrepresent their true feelings and behaviors. To mitigate these biases, future research should include objective measures of adherence, such as pharmacy refill records or electronic monitoring, alongside qualitative methods that capture the complexities of empowerment and adherence behaviors in breast cancer patients. Additionally, this study relies on single-site data, which may limit the generalizability of the findings. The healthcare infrastructure in South Korea varies significantly between urban and rural areas, which could influence the experiences and behaviors of breast cancer patients. For instance, patients in urban settings may have greater access to specialized medical facilities, support services, and educational resources compared to those in rural areas. This disparity could lead to variations in factors such as medication adherence, empowerment levels, and overall health outcomes. Consequently, the results observed in this study may not accurately reflect the experiences of breast cancer patients across different regions of South Korea. Future research should explore multi-site data collection, incorporating diverse populations from both urban and rural settings, to assess how these healthcare infrastructure differences might impact patient experiences and results. Additionally, cultural, societal, and healthcare system differences can affect adherence, depression rates, and perceptions of empowerment, highlighting the need for research across diverse settings. Future studies should employ specific methodologies, such as longitudinal designs that track medication adherence, depression, and empowerment over time. This approach would allow researchers to observe changes and trends in these variables, providing deeper insights into their relationships. Furthermore, utilizing mixed methods that combine quantitative surveys, and qualitative interviews can enrich the findings by capturing the nuanced experiences and perspectives of patients. Such comprehensive research designs would facilitate a better understanding of the factors influencing treatment adherence and overall well-being in various cultural contexts.
Conclusions
This study illuminated the associations between depression, empowerment, and adherence in patients with breast cancer receiving anti-hormonal therapy. The results confirm that depression negatively affects adherence, corroborating prior research linking psychological distress to reduced adherence with treatment regimens. Conversely, our findings highlight empowerment as a facilitator of adherence, suggesting that patients who feel more in control of their treatment decisions are more likely to adhere to prescribed schedules. Given the significance of empowerment, characterized by intrapersonal and behavioral factors, there is a pressing need for healthcare providers to actively engage their patients through targeted interventions. Recommended strategies may include educational programs to enhance treatment understanding, counseling services to address psychological distress, and support groups to foster a sense of community and personal efficacy. The statistical analyses indicated that younger age, employment status, and higher empowerment levels were associated with better adherence. This aligns with the understanding that economic stability and a sense of personal efficacy and control can significantly influence adherence to treatment protocols.
Acknowledgements
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Declarations
Ethics approval and consent to participate
This study received IRB approval from the Institutional Review Board of Wonkwang University Hospital, with the approval number WKUH-2022-05-43. The researcher personally explained the purpose and content of the study, the guarantee of participants’ anonymity, and the protection of individual ethical aspects. Data collection was then conducted with patients who agreed to participate in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
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