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The impact of depressive symptoms and psychosocial factors on medication adherence in cardiovascular disease
Patient Education and Counseling 60 (2006) 187–193 www.elsevier.com/locate/pateducou
The impact of depressive symptoms and psychosocial factors on medication adherence in cardiovascular disease Catherine Bane a,1, Carmel M. Hughes b,*, James C. McElnay c,2 b
a Programme Manager, Research and Development Office, Belfast, Northern Ireland, UK Reader, School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast Co., Antrim BT9 7BL, Belfast, Northern Ireland, UK c Professor of Pharmacy Practice, School of Pharmacy, Queen’s University Belfast, Belfast, Northern Ireland, UK
Received 7 July 2004; received in revised form 4 January 2005; accepted 4 January 2005
Abstract Objective: This study sought to determine the influence of depression and psychosocial factors on medication adherence in cardiovascular disease. Methods: A questionnaire including measures of depression, beliefs about medicines, health locus of control and adherence to medication (self-report) was completed by 122 outpatients attending a cardiac clinic. Results: Analysis revealed that 14.8% of participants were non-adherent with their cardiovascular medication and 41.7% had scores indicative of depressive symptoms as determined by the Center for Epidemiological Studies Depression Scale (CES-D). Higher scores on this scale and strong concern scores on the Beliefs about Medicines Questionnaire about the potential adverse effects of using medication as prescribed were found to be associated with self-reported non-adherence. Discussion and conclusion: These findings imply that the relationship between depressive symptoms in cardiovascular patients, together with certain psychosocial factors, could have negative consequences for adherence to medication. Practice implications: Given that there is emerging evidence to suggest an association between depression and medication non-adherence, healthcare professionals should consider this when dealing with cardiovascular patients. # 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Adherence; Cardiovascular disease; Depression; Health beliefs; Psychosocial
1. Introduction Patient non-adherence with medical advice is one of the major problems in the management of chronic diseases, and has been associated with increased morbidity and mortality rates in hypertension, coronary heart disease and heart failure [1]. It has been estimated that on average, only 50% of patients with chronic diseases adhere to the drug therapy prescribed for them [2]. * Corresponding author. Tel.: +44 28 90 272 147; fax: +44 28 90 977 794. E-mail addresses: [email protected] (C. Bane), [email protected] (C.M. Hughes), [email protected] (J.C. McElnay). 1 Tel.: +44 28 90 553 617; fax: +44 28 90 553 674. 2 Tel.: +44 28 90 975 800; fax: +44 28 90 977 794.
Although a large number of variables have been associated with altered medication adherence, including demographic, medical and personality factors, few of these can be considered as consistently predicting adherence [3]. It has, however, been suggested that psychological and emotional factors underlie and predict adherence behaviour more so than other factors. It has also been widely reported in the literature that patients’ beliefs about medications impact on adherence [4–6]. Furthermore, psychosocial models such as social cognitive models (SCMs) are currently receiving increasing attention in the literature as a means to increase our understanding of the beliefs and cognitions which determine a wide range of health behaviours [7], often with a high degree of success [8–10]. Depression, although prevalent, is largely undiagnosed in patients with cardiovascular disease [11] and some studies
0738-3991/$ – see front matter # 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.pec.2005.01.003
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have suggested that depression may have an impact on medication taking [12,13]. Furthermore, depressive symptoms are believed to have a negative effect on achievement and maintenance of healthy behaviour changes, for example, during rehabilitation following myocardial infarction [14]. Major depression has been reported to be a strong predictor of a second myocardial infarction [15–17] and increased mortality rates have been documented in depressed patients with heart disease [18–20]. The aim of the present study was to examine the role of depression and psychosocial factors (beliefs about medicines, multidimensional health locus of control, and perceived health competence), together with socio-demographic and medical factors, in medication adherence in patients with cardiovascular disease.
2. Methods 2.1. Study site The study site was an outpatient cardiac clinic at the Belfast City Hospital (a 900 bed tertiary referral centre) in Northern Ireland. Ethical approval for the study was obtained from the local Research Ethics Committee. 2.2. Study inclusion and exclusion criteria Outpatients who were receiving prescribed medication for cardiovascular disease (ischaemic heart disease, congestive heart failure) were approached in the cardiac clinic waiting room by one of the investigators (CB), and invited to participate in the study. Patients were enrolled in the study after obtaining written, informed consent. Patients were excluded from the study if they had a diagnosis of Alzheimer’s disease or dementia in their medical records. The target sample size was 200 patients. 2.3. Chart review The following details (defined as medical factors) were collected from each patient’s chart, using a standard proforma: age, sex, weight, serum creatinine concentration, date of diagnosis of cardiovascular disease, number of admissions to hospital due to cardiovascular disease in the previous year (and length of stay), whether the patient had received surgical treatment for their heart condition, ejection fraction (if appropriate), medical history, prescribed drugs and the drug regimens, clinic attendance and any comments on patient adherence. 2.4. Measures A custom-designed study questionnaire was either administered to patients by face-to-face interview or was self-completed by patients, depending on patient preference.
The following measures were included in the questionnaire. All measures were unchanged apart from one minor addition to the Adherence scale. 2.4.1. Adherence Adherence with cardiovascular medication was assessed using patients’ self-report [21,22]. Data from computerised prescription medication records (PMRs) were also sought from the patients’ community pharmacists. A rate of 80– 120% was considered to indicate acceptable adherence [23,24]. Due to variability in doses of some products e.g. nitrate sprays, or specific instructions to take an extra dose of a diuretic in heart failure it was necessary to extend the acceptable adherence range to 120%. In order for a patient to be deemed adherent, they had to be within this range for all cardiovascular medications assessed. The self-report measure was based on responses to four items which reflect different aspects of medication non-adherence. The measure is based on the self-reported medication taking scale [25] but was adapted to include a measure of overadherence, as well as a measure of the extent of underadherence; this was the only change made to this scale. If scores on any one of the four items fell outside the 80–120% range, the patient was judged to be non-adherent. PMR printouts were requested for each patient, for the previous 6–12 months, depending on the period for which PMR data were available from the community pharmacies nominated by patients. The PMR measure of adherence was calculated as follows: ðunit doses dispensed divided by quantity to be taken per dayÞ % adherence ¼ 100 number of days in interval covered by prescriptions Clinic attendance records were also obtained from patients’ charts as a further indicator of adherence to medical advice. 2.4.2. The Center for Epidemiological Studies Depression Scale (CES-D) The CES-D [26] is a 20-item scale which measures current levels of depressive symptomatology. A score of 16 or more is indicative of symptoms of depression. The CES-D is not used as a diagnostic tool, but rather as a screening test, to identify groups at risk of depression or in need of treatment [27]. 2.4.3. The Beliefs about Medicines Questionnaire (BMQ) The BMQ [28], a 10-item scale was used to gather data on patient beliefs about their prescribed medication. Items were tailored to make them specific to taking medications for cardiovascular disease. The scale comprises two 5-item factors assessing beliefs about the necessity of prescribed medication (Necessity scale) and concerns about prescribed medication based on beliefs about the danger of dependence and long-term toxicity of medicines (Concern scale). A
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further measure, the necessity-concern differential was calculated by subtracting scores on the Concern scale from scores on the Necessity scale. This may be thought of as the result of a cost-benefit analysis for each patient where perceptions of cost (concerns) are weighed against their perception of benefit (necessity beliefs) [28]. 2.4.4. The Multidimensional Health Locus of Control Scales (MHLC) The MHLC scale (form C) [29] consists of 18-items that measure expectancy beliefs with respect to health along three dimensions: Internal, Powerful Others, and Chance. Internal refers to the extent to which individuals believe their health is under the influence of their own actions. Powerful others refers to the expectancy that primarily doctors and other healthcare professionals determine health. The Chance subscale refers to generalised expectancies that factors which determine health are things such as luck, fate or chance [30]. It is also recommended that considering measures of self-efficacy expectations or behavioural competence e.g. the Perceived Health Competence Scale (PHCS), along with measures of HLC may enhance prediction of health-related behaviour [31]. Hence, the 8item PHCS scale which measures the degree to which an individual feels capable of effectively managing his or her health outcomes, was also included in the study questionnaire [32]. 2.5. Data analysis Data from the questionnaire and chart review for each patient were entered into SPSS for statistical analysis. Relationships between the variables under study and adherence were assessed using a variety of statistical tests including Mann–Whitney U-tests, x2-analysis and regression analysis. When performing x2-analysis, the Fisher’s Exact test was used when cells had an expected count of less than 5, otherwise the likelihood ratio was used to determine significance. For all statistical analyses, pvalues less than 0.05 were judged to be significant. Where mean values are presented, the standard deviations are reported in brackets. Due to a poor response rate from community pharmacists, PMR data were available for only 45 of the patients and has not been included in Section 3.
measure of reliability; the results were acceptable i.e. >0.5. Participants’ mean age was 54.51 years (12.47); 73 (59.8%) of the participants were male, and 49 (41.2%) were female. 3.1. Self-report measures of adherence with prescribed medication Based on the self-report measure, just over 85% of patients were deemed adherent with their medication (85.2%; n = 104), while 14.8% were non-adherent (n = 18), according to the measurement criteria i.e. fell within the 80–120% range. 3.2. Socio-demographic factors A summary of participants’ socio-demographic details is presented in Table 1 [33]. A Mann–Whitney U-test revealed a significant relationship between age and self-reported adherence, with older patients more likely to be adherent ( p < 0.05). In terms of marital status, x2-analysis revealed a significant association between marital status and medication adherence, with single patients being more likely to be non-adherent with medication, as measured by self-report ( p < 0.05, Fishers Exact test). x2-analysis also revealed a significant association between living arrangements and medication adherence, indicating that patients who lived alone were more likely to be non-adherent ( p < 0.05, Fishers Exact test). Participants had spent a mean of 11.77 (3.09) years in education. A Mann–Whitney U-test revealed a significant association between number of years spent in education and adherence, with those patients who spent a higher number of years in education, tending to report non-adherence with their medication ( p < 0.05).
Table 1 Summary of patients’ socio-demographic details Living arrangements
Percent
Living alone (independently/support if needed from a family member or warden) Living with others (non-family members, spouse/partner, family) Last educational establishment attended Secondary school (including technical college and grammar school) University
14.1
a
3. Results Data were collected from 122 patients with cardiovascular disease. The majority of patients chose to selfadminister the questionnaire (108 versus 14 who were interviewed face-to-face). There were no differences in the two methods of administration in terms of the responses. Chronbach’s-a reliability coefficients were calculated for each of the questionnaire variables, as a
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NS-SEC analytic classes 1. Higher managerial and professional occupations 2. Lower managerial and professional occupations 3. Intermediate occupations 4. Small employers and own account workers 5. Lower supervisory and technical occupations 6. Semi-routine occupations 7. Routine occupations 8. Never worked, long-term unemployed and occupations not stated or inadequately described a
National Statistics Socio-Economic Classification [33].
85.9 Percent 87.5 12.5 Percent 6.7 10.7 11.5 7.4 10.7 9.0 7.4 36.6
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There were no significant associations ( p > 0.05) between socio-economic classification and self-reported adherence with medication. 3.3. Medication and medical factors The mean number of prescribed cardiovascular medications per patient was 4.28 (2.35). Statistical analysis failed to identify any significant relationships between medical factors (as determined by chart review, and defined as number of prescribed medications, use of OTC medication, number of hospitalisations related to cardiovascular disease during the previous year, whether the patient had undergone a surgical procedure related to their cardiovascular disease, number of years since first diagnosed with cardiovascular disease, number of years in regular attendance at the cardiac clinic) and self-reported adherence with cardiovascular medication. The chart reviews revealed that patients had a mean of 1.68 (1.38) medical conditions. As expected, the most commonly recorded medical conditions were those that affected the cardiovascular system: ischaemic heart disease 45% (including angina); hypertension 25%; hypercholesterolaemia 13%; congestive heart failure 9% and myocardial infarction 8%. Other recorded medical conditions included hyperthyroidism, diabetes, renal failure or transplant, peptic ulcer and depression (2.5% of patients). x2-analysis failed to identify any relationship ( p > 0.05) between number of medical conditions and adherence to medication as determined by self-report. 3.4. Adherence and depression According to the CES-D scale, 41.7% of the patients interviewed were found to have scores indicative of depressive symptoms i.e. >16. The mean score on the CES-D for this population of cardiovascular outpatients was 16.8 (12.72). However, only 2.5% of these patients had a diagnosis of depression recorded in their chart. x2-analysis revealed a significant association between high scores on the CES-D scale and self-reported non-adherence with cardiovascular medication ( p < 0.05), i.e. non-adherent patients were more likely to obtain scores above 16 on the CES-D
Fig. 2. Responses to Necessity and Concern scales of the BMQ according to adherence measured by self-report.
scale (see Fig. 1). Furthermore, a significant association ( p < 0.05) was found between scores on the Concern scale of the BMQ and scores on the CES-D scale, with those patients having scores above 16 on the CES-D scale (indicating depression), obtaining higher scores on the Concern scale. 3.5. Adherence and beliefs about medicines The majority (94.5%) of patients reported strong beliefs in the necessity of their medication (scores greater than scale midpoint). However, the majority (84.9%) also had strong concerns about the potential adverse effects of using their medication (scores greater than scale midpoint). Necessity scores were lower than concern scores for 17.2% of the sample (negative values on the necessity–concerns differential). A Mann–Whitney U-test revealed a significant association between scores on the Concern scale, and patient adherence ( p < 0.05). Comparison of scores demonstrated that non-adherent patients were more likely to have higher scores on the Concern scale, i.e. beliefs about the danger of dependence and long-term toxicity of medicines (see Fig. 2). Analysis failed to identify any significant association between Necessity scores and adherence with prescribed medications ( p > 0.05). Comparison of scores on the Necessity–Concerns differential for the adherent and nonadherent groups, again using a Mann–Whitney U-test, revealed significant differences between mean scores for the adherent and non-adherent groups ( p < 0.05). x2-analysis of positive and negative scores on the Necessity–Concerns differential scale and adherence, indicated that adherent patients had higher scores on the Necessity–Concerns differential and so were more likely to perceive that the necessity of their medication outweighed concerns about taking it ( p < 0.05). 3.6. Adherence and health locus of control
Fig. 1. Relationship between adherence and depression as determined by CES-D scores (scores >16 indicate depressive symptoms).
Analysis using Mann–Whitney U-tests failed to identify any significant differences between scores on the Internal, Powerful Others and Chance subscales and self-reported
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a similar low level of non-adherence (13%) compared with 14% in our study [34]. 4.1. Discussion
Fig. 3. Relationship between high and low PHCS scores and depression, as determined by CES-D scores (scores >16 indicate depressive symptoms).
adherence. However, it is recommended that HLC variables be examined in interaction with a measure of perceived health competence [31]. A hierarchical regression analysis was therefore conducted to determine any interaction effects of the HLC variables and scores on the PHCS scale. With each subsequent step of the regression analysis an interaction term was entered individually, until all possible interactions had been examined. Results of the primary regression analysis revealed significant effects for scores on the following scales: Internal, Powerful Others, PHCS, and adherence behaviour ( p < 0.05). The main effects were qualified by a significant interaction effect between Internal scores, in combination with PHCS scores ( p < 0.05), but the direction of the relationship between these two variables was unclear. Including the interaction term in the regression equation explained 12.5% of the variance in adherence behaviour. 3.7. Adherence and perceived health competence Analysis using Mann–Whitney U-tests did not reveal any significant differences between scores on the PHCS and selfreported adherence with medications, when examined in isolation from the HLC measure. However, further analysis with the Mann–Whitney U-test revealed a significant association between low scores on the PHCS (scores lower than scale mid-point) and scores on the CES-D scale ( p < 0.05), with patients who had scores above 16 on the CES-D scale (indicating depressive symptoms) obtaining lower scores on the PHCS (see Fig. 3).
4. Discussion and conclusion Results indicated that a number of psychosocial factors impacted on patient adherence in this sample of patients with cardiovascular disease. These findings should be interpreted with some caution due to potential underreporting of non-adherence by patients in this study. However, a recent publication reporting on non-adherence in patients taking cardiovascular medicines has also reported
The most important findings in this study relate to depression and adherence to medication in this patient group. This study revealed a large discrepancy between the number of patients who achieved scores indicative of depression on the CES-D and the number of patients who had a diagnosis of depression recorded in their chart. This is consistent with the assertion that depression is seldom diagnosed or treated in cardiac patients [11]. The mean score on the CES-D for this population of cardiovascular outpatients was 16.8 (12.72) which is considerably higher than the mean CES-D scores of 9.1 for adults in the community [35]. Scores on the depression scale appeared to have implications for adherence, as high scores on the CESD were found to be associated with reported non-adherence with cardiovascular medication. In addition, high scores on the CES-D were found to be associated with high scores on the Concern scale of the BMQ, indicating that those patients who had high depression scores, also had strong concerns about taking their medication. A meta-analysis of studies has previously found that depression is associated with non-adherence with medical advice in a number of disease states [13]. Although there has been little research to date examining the relationship between depression and adherence in cardiovascular disease, the few studies which have been carried out in this area show a significant relationship between these variables [12,19,36– 38]. The findings of the present study support the need for further action by clinicians in this area; this is particularly pertinent given the high numbers of patients in this population who were potentially affected by depression. The exact mechanism linking depression with adverse outcomes such as second myocardial infarction or high mortality rates in patients with cardiovascular disease remains unknown, however, it has been suggested that patients with cardiovascular disease who are depressed are less likely to adhere to prescribed medical regimens, which may account for poorer outcomes [12,19]. Further research is also required to determine whether treating depression can reduce the morbidity and mortality risk among patients suffering from cardiovascular disease, and to establish the safety and efficacy of antidepressant drug use in this patient population [20]. A relationship was found between low perceived health competence scores and high scores on the CES-D; this relationship has been reported elsewhere [32]. This may suggest that people who do not feel capable of effectively managing their health outcomes are more likely to report higher levels of depressive symptomatology. The direction of this relationship (low perceived health competence scores causes depression or vice versa) is unclear. Furthermore, as noted earlier, the CES-D is not a diagnostic tool, and should be used only to identify groups at
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risk of clinical depression, who may benefit from further investigation and treatment. This research also supports the view that patients held strong beliefs about the necessity of their medications, yet simultaneously had strong concerns about potential adverse effects. Patients’ beliefs may form the foundations of decisions as to whether medication should be taken as prescribed [28] and these findings have implications for how this can be managed in clinical practice. 4.2. Conclusions Further research is necessary to establish the precise relationship between depression, other psycho-social factors (e.g. beliefs about medications) and adherence, which would provide healthcare professionals with an insight into the relationship between where patients believe the control over their health lies, and adherence with medication. Such an insight has implications for the design of interventions aimed at enhancing adherence rates, and for adoption of the most appropriate patient-healthcare provider consultation style. 4.3. Practice implications A high percentage (41.7%) of patients in the present study with cardiovascular disease reported symptoms indicative of depression. Given that there is emerging evidence to suggest an association between depression and non-adherence, healthcare professionals should consider this when dealing with cardiovascular patients. Such patients may benefit from treatment aimed at alleviating depression, which may in turn, enhance adherence rates. The majority of patients held strong concerns about taking their prescribed medications, and those who perceived their concerns to outweigh the necessity of taking medications, tended to be non-adherent with medication. Concerns may be addressed during concordant consultations with healthcare professionals, or through patient education.
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The impact of depressive symptoms and psychosocial factors on medication adherence in cardiovascular disease Catherine Bane a,1, Carmel M. Hughes b,*, James C. McElnay c,2 b
a Programme Manager, Research and Development Office, Belfast, Northern Ireland, UK Reader, School of Pharmacy, Queen’s University Belfast, 97 Lisburn Road, Belfast Co., Antrim BT9 7BL, Belfast, Northern Ireland, UK c Professor of Pharmacy Practice, School of Pharmacy, Queen’s University Belfast, Belfast, Northern Ireland, UK
Received 7 July 2004; received in revised form 4 January 2005; accepted 4 January 2005
Abstract Objective: This study sought to determine the influence of depression and psychosocial factors on medication adherence in cardiovascular disease. Methods: A questionnaire including measures of depression, beliefs about medicines, health locus of control and adherence to medication (self-report) was completed by 122 outpatients attending a cardiac clinic. Results: Analysis revealed that 14.8% of participants were non-adherent with their cardiovascular medication and 41.7% had scores indicative of depressive symptoms as determined by the Center for Epidemiological Studies Depression Scale (CES-D). Higher scores on this scale and strong concern scores on the Beliefs about Medicines Questionnaire about the potential adverse effects of using medication as prescribed were found to be associated with self-reported non-adherence. Discussion and conclusion: These findings imply that the relationship between depressive symptoms in cardiovascular patients, together with certain psychosocial factors, could have negative consequences for adherence to medication. Practice implications: Given that there is emerging evidence to suggest an association between depression and medication non-adherence, healthcare professionals should consider this when dealing with cardiovascular patients. # 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Adherence; Cardiovascular disease; Depression; Health beliefs; Psychosocial
1. Introduction Patient non-adherence with medical advice is one of the major problems in the management of chronic diseases, and has been associated with increased morbidity and mortality rates in hypertension, coronary heart disease and heart failure [1]. It has been estimated that on average, only 50% of patients with chronic diseases adhere to the drug therapy prescribed for them [2]. * Corresponding author. Tel.: +44 28 90 272 147; fax: +44 28 90 977 794. E-mail addresses: [email protected] (C. Bane), [email protected] (C.M. Hughes), [email protected] (J.C. McElnay). 1 Tel.: +44 28 90 553 617; fax: +44 28 90 553 674. 2 Tel.: +44 28 90 975 800; fax: +44 28 90 977 794.
Although a large number of variables have been associated with altered medication adherence, including demographic, medical and personality factors, few of these can be considered as consistently predicting adherence [3]. It has, however, been suggested that psychological and emotional factors underlie and predict adherence behaviour more so than other factors. It has also been widely reported in the literature that patients’ beliefs about medications impact on adherence [4–6]. Furthermore, psychosocial models such as social cognitive models (SCMs) are currently receiving increasing attention in the literature as a means to increase our understanding of the beliefs and cognitions which determine a wide range of health behaviours [7], often with a high degree of success [8–10]. Depression, although prevalent, is largely undiagnosed in patients with cardiovascular disease [11] and some studies
0738-3991/$ – see front matter # 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.pec.2005.01.003
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have suggested that depression may have an impact on medication taking [12,13]. Furthermore, depressive symptoms are believed to have a negative effect on achievement and maintenance of healthy behaviour changes, for example, during rehabilitation following myocardial infarction [14]. Major depression has been reported to be a strong predictor of a second myocardial infarction [15–17] and increased mortality rates have been documented in depressed patients with heart disease [18–20]. The aim of the present study was to examine the role of depression and psychosocial factors (beliefs about medicines, multidimensional health locus of control, and perceived health competence), together with socio-demographic and medical factors, in medication adherence in patients with cardiovascular disease.
2. Methods 2.1. Study site The study site was an outpatient cardiac clinic at the Belfast City Hospital (a 900 bed tertiary referral centre) in Northern Ireland. Ethical approval for the study was obtained from the local Research Ethics Committee. 2.2. Study inclusion and exclusion criteria Outpatients who were receiving prescribed medication for cardiovascular disease (ischaemic heart disease, congestive heart failure) were approached in the cardiac clinic waiting room by one of the investigators (CB), and invited to participate in the study. Patients were enrolled in the study after obtaining written, informed consent. Patients were excluded from the study if they had a diagnosis of Alzheimer’s disease or dementia in their medical records. The target sample size was 200 patients. 2.3. Chart review The following details (defined as medical factors) were collected from each patient’s chart, using a standard proforma: age, sex, weight, serum creatinine concentration, date of diagnosis of cardiovascular disease, number of admissions to hospital due to cardiovascular disease in the previous year (and length of stay), whether the patient had received surgical treatment for their heart condition, ejection fraction (if appropriate), medical history, prescribed drugs and the drug regimens, clinic attendance and any comments on patient adherence. 2.4. Measures A custom-designed study questionnaire was either administered to patients by face-to-face interview or was self-completed by patients, depending on patient preference.
The following measures were included in the questionnaire. All measures were unchanged apart from one minor addition to the Adherence scale. 2.4.1. Adherence Adherence with cardiovascular medication was assessed using patients’ self-report [21,22]. Data from computerised prescription medication records (PMRs) were also sought from the patients’ community pharmacists. A rate of 80– 120% was considered to indicate acceptable adherence [23,24]. Due to variability in doses of some products e.g. nitrate sprays, or specific instructions to take an extra dose of a diuretic in heart failure it was necessary to extend the acceptable adherence range to 120%. In order for a patient to be deemed adherent, they had to be within this range for all cardiovascular medications assessed. The self-report measure was based on responses to four items which reflect different aspects of medication non-adherence. The measure is based on the self-reported medication taking scale [25] but was adapted to include a measure of overadherence, as well as a measure of the extent of underadherence; this was the only change made to this scale. If scores on any one of the four items fell outside the 80–120% range, the patient was judged to be non-adherent. PMR printouts were requested for each patient, for the previous 6–12 months, depending on the period for which PMR data were available from the community pharmacies nominated by patients. The PMR measure of adherence was calculated as follows: ðunit doses dispensed divided by quantity to be taken per dayÞ % adherence ¼ 100 number of days in interval covered by prescriptions Clinic attendance records were also obtained from patients’ charts as a further indicator of adherence to medical advice. 2.4.2. The Center for Epidemiological Studies Depression Scale (CES-D) The CES-D [26] is a 20-item scale which measures current levels of depressive symptomatology. A score of 16 or more is indicative of symptoms of depression. The CES-D is not used as a diagnostic tool, but rather as a screening test, to identify groups at risk of depression or in need of treatment [27]. 2.4.3. The Beliefs about Medicines Questionnaire (BMQ) The BMQ [28], a 10-item scale was used to gather data on patient beliefs about their prescribed medication. Items were tailored to make them specific to taking medications for cardiovascular disease. The scale comprises two 5-item factors assessing beliefs about the necessity of prescribed medication (Necessity scale) and concerns about prescribed medication based on beliefs about the danger of dependence and long-term toxicity of medicines (Concern scale). A
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further measure, the necessity-concern differential was calculated by subtracting scores on the Concern scale from scores on the Necessity scale. This may be thought of as the result of a cost-benefit analysis for each patient where perceptions of cost (concerns) are weighed against their perception of benefit (necessity beliefs) [28]. 2.4.4. The Multidimensional Health Locus of Control Scales (MHLC) The MHLC scale (form C) [29] consists of 18-items that measure expectancy beliefs with respect to health along three dimensions: Internal, Powerful Others, and Chance. Internal refers to the extent to which individuals believe their health is under the influence of their own actions. Powerful others refers to the expectancy that primarily doctors and other healthcare professionals determine health. The Chance subscale refers to generalised expectancies that factors which determine health are things such as luck, fate or chance [30]. It is also recommended that considering measures of self-efficacy expectations or behavioural competence e.g. the Perceived Health Competence Scale (PHCS), along with measures of HLC may enhance prediction of health-related behaviour [31]. Hence, the 8item PHCS scale which measures the degree to which an individual feels capable of effectively managing his or her health outcomes, was also included in the study questionnaire [32]. 2.5. Data analysis Data from the questionnaire and chart review for each patient were entered into SPSS for statistical analysis. Relationships between the variables under study and adherence were assessed using a variety of statistical tests including Mann–Whitney U-tests, x2-analysis and regression analysis. When performing x2-analysis, the Fisher’s Exact test was used when cells had an expected count of less than 5, otherwise the likelihood ratio was used to determine significance. For all statistical analyses, pvalues less than 0.05 were judged to be significant. Where mean values are presented, the standard deviations are reported in brackets. Due to a poor response rate from community pharmacists, PMR data were available for only 45 of the patients and has not been included in Section 3.
measure of reliability; the results were acceptable i.e. >0.5. Participants’ mean age was 54.51 years (12.47); 73 (59.8%) of the participants were male, and 49 (41.2%) were female. 3.1. Self-report measures of adherence with prescribed medication Based on the self-report measure, just over 85% of patients were deemed adherent with their medication (85.2%; n = 104), while 14.8% were non-adherent (n = 18), according to the measurement criteria i.e. fell within the 80–120% range. 3.2. Socio-demographic factors A summary of participants’ socio-demographic details is presented in Table 1 [33]. A Mann–Whitney U-test revealed a significant relationship between age and self-reported adherence, with older patients more likely to be adherent ( p < 0.05). In terms of marital status, x2-analysis revealed a significant association between marital status and medication adherence, with single patients being more likely to be non-adherent with medication, as measured by self-report ( p < 0.05, Fishers Exact test). x2-analysis also revealed a significant association between living arrangements and medication adherence, indicating that patients who lived alone were more likely to be non-adherent ( p < 0.05, Fishers Exact test). Participants had spent a mean of 11.77 (3.09) years in education. A Mann–Whitney U-test revealed a significant association between number of years spent in education and adherence, with those patients who spent a higher number of years in education, tending to report non-adherence with their medication ( p < 0.05).
Table 1 Summary of patients’ socio-demographic details Living arrangements
Percent
Living alone (independently/support if needed from a family member or warden) Living with others (non-family members, spouse/partner, family) Last educational establishment attended Secondary school (including technical college and grammar school) University
14.1
a
3. Results Data were collected from 122 patients with cardiovascular disease. The majority of patients chose to selfadminister the questionnaire (108 versus 14 who were interviewed face-to-face). There were no differences in the two methods of administration in terms of the responses. Chronbach’s-a reliability coefficients were calculated for each of the questionnaire variables, as a
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NS-SEC analytic classes 1. Higher managerial and professional occupations 2. Lower managerial and professional occupations 3. Intermediate occupations 4. Small employers and own account workers 5. Lower supervisory and technical occupations 6. Semi-routine occupations 7. Routine occupations 8. Never worked, long-term unemployed and occupations not stated or inadequately described a
National Statistics Socio-Economic Classification [33].
85.9 Percent 87.5 12.5 Percent 6.7 10.7 11.5 7.4 10.7 9.0 7.4 36.6
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There were no significant associations ( p > 0.05) between socio-economic classification and self-reported adherence with medication. 3.3. Medication and medical factors The mean number of prescribed cardiovascular medications per patient was 4.28 (2.35). Statistical analysis failed to identify any significant relationships between medical factors (as determined by chart review, and defined as number of prescribed medications, use of OTC medication, number of hospitalisations related to cardiovascular disease during the previous year, whether the patient had undergone a surgical procedure related to their cardiovascular disease, number of years since first diagnosed with cardiovascular disease, number of years in regular attendance at the cardiac clinic) and self-reported adherence with cardiovascular medication. The chart reviews revealed that patients had a mean of 1.68 (1.38) medical conditions. As expected, the most commonly recorded medical conditions were those that affected the cardiovascular system: ischaemic heart disease 45% (including angina); hypertension 25%; hypercholesterolaemia 13%; congestive heart failure 9% and myocardial infarction 8%. Other recorded medical conditions included hyperthyroidism, diabetes, renal failure or transplant, peptic ulcer and depression (2.5% of patients). x2-analysis failed to identify any relationship ( p > 0.05) between number of medical conditions and adherence to medication as determined by self-report. 3.4. Adherence and depression According to the CES-D scale, 41.7% of the patients interviewed were found to have scores indicative of depressive symptoms i.e. >16. The mean score on the CES-D for this population of cardiovascular outpatients was 16.8 (12.72). However, only 2.5% of these patients had a diagnosis of depression recorded in their chart. x2-analysis revealed a significant association between high scores on the CES-D scale and self-reported non-adherence with cardiovascular medication ( p < 0.05), i.e. non-adherent patients were more likely to obtain scores above 16 on the CES-D
Fig. 2. Responses to Necessity and Concern scales of the BMQ according to adherence measured by self-report.
scale (see Fig. 1). Furthermore, a significant association ( p < 0.05) was found between scores on the Concern scale of the BMQ and scores on the CES-D scale, with those patients having scores above 16 on the CES-D scale (indicating depression), obtaining higher scores on the Concern scale. 3.5. Adherence and beliefs about medicines The majority (94.5%) of patients reported strong beliefs in the necessity of their medication (scores greater than scale midpoint). However, the majority (84.9%) also had strong concerns about the potential adverse effects of using their medication (scores greater than scale midpoint). Necessity scores were lower than concern scores for 17.2% of the sample (negative values on the necessity–concerns differential). A Mann–Whitney U-test revealed a significant association between scores on the Concern scale, and patient adherence ( p < 0.05). Comparison of scores demonstrated that non-adherent patients were more likely to have higher scores on the Concern scale, i.e. beliefs about the danger of dependence and long-term toxicity of medicines (see Fig. 2). Analysis failed to identify any significant association between Necessity scores and adherence with prescribed medications ( p > 0.05). Comparison of scores on the Necessity–Concerns differential for the adherent and nonadherent groups, again using a Mann–Whitney U-test, revealed significant differences between mean scores for the adherent and non-adherent groups ( p < 0.05). x2-analysis of positive and negative scores on the Necessity–Concerns differential scale and adherence, indicated that adherent patients had higher scores on the Necessity–Concerns differential and so were more likely to perceive that the necessity of their medication outweighed concerns about taking it ( p < 0.05). 3.6. Adherence and health locus of control
Fig. 1. Relationship between adherence and depression as determined by CES-D scores (scores >16 indicate depressive symptoms).
Analysis using Mann–Whitney U-tests failed to identify any significant differences between scores on the Internal, Powerful Others and Chance subscales and self-reported
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a similar low level of non-adherence (13%) compared with 14% in our study [34]. 4.1. Discussion
Fig. 3. Relationship between high and low PHCS scores and depression, as determined by CES-D scores (scores >16 indicate depressive symptoms).
adherence. However, it is recommended that HLC variables be examined in interaction with a measure of perceived health competence [31]. A hierarchical regression analysis was therefore conducted to determine any interaction effects of the HLC variables and scores on the PHCS scale. With each subsequent step of the regression analysis an interaction term was entered individually, until all possible interactions had been examined. Results of the primary regression analysis revealed significant effects for scores on the following scales: Internal, Powerful Others, PHCS, and adherence behaviour ( p < 0.05). The main effects were qualified by a significant interaction effect between Internal scores, in combination with PHCS scores ( p < 0.05), but the direction of the relationship between these two variables was unclear. Including the interaction term in the regression equation explained 12.5% of the variance in adherence behaviour. 3.7. Adherence and perceived health competence Analysis using Mann–Whitney U-tests did not reveal any significant differences between scores on the PHCS and selfreported adherence with medications, when examined in isolation from the HLC measure. However, further analysis with the Mann–Whitney U-test revealed a significant association between low scores on the PHCS (scores lower than scale mid-point) and scores on the CES-D scale ( p < 0.05), with patients who had scores above 16 on the CES-D scale (indicating depressive symptoms) obtaining lower scores on the PHCS (see Fig. 3).
4. Discussion and conclusion Results indicated that a number of psychosocial factors impacted on patient adherence in this sample of patients with cardiovascular disease. These findings should be interpreted with some caution due to potential underreporting of non-adherence by patients in this study. However, a recent publication reporting on non-adherence in patients taking cardiovascular medicines has also reported
The most important findings in this study relate to depression and adherence to medication in this patient group. This study revealed a large discrepancy between the number of patients who achieved scores indicative of depression on the CES-D and the number of patients who had a diagnosis of depression recorded in their chart. This is consistent with the assertion that depression is seldom diagnosed or treated in cardiac patients [11]. The mean score on the CES-D for this population of cardiovascular outpatients was 16.8 (12.72) which is considerably higher than the mean CES-D scores of 9.1 for adults in the community [35]. Scores on the depression scale appeared to have implications for adherence, as high scores on the CESD were found to be associated with reported non-adherence with cardiovascular medication. In addition, high scores on the CES-D were found to be associated with high scores on the Concern scale of the BMQ, indicating that those patients who had high depression scores, also had strong concerns about taking their medication. A meta-analysis of studies has previously found that depression is associated with non-adherence with medical advice in a number of disease states [13]. Although there has been little research to date examining the relationship between depression and adherence in cardiovascular disease, the few studies which have been carried out in this area show a significant relationship between these variables [12,19,36– 38]. The findings of the present study support the need for further action by clinicians in this area; this is particularly pertinent given the high numbers of patients in this population who were potentially affected by depression. The exact mechanism linking depression with adverse outcomes such as second myocardial infarction or high mortality rates in patients with cardiovascular disease remains unknown, however, it has been suggested that patients with cardiovascular disease who are depressed are less likely to adhere to prescribed medical regimens, which may account for poorer outcomes [12,19]. Further research is also required to determine whether treating depression can reduce the morbidity and mortality risk among patients suffering from cardiovascular disease, and to establish the safety and efficacy of antidepressant drug use in this patient population [20]. A relationship was found between low perceived health competence scores and high scores on the CES-D; this relationship has been reported elsewhere [32]. This may suggest that people who do not feel capable of effectively managing their health outcomes are more likely to report higher levels of depressive symptomatology. The direction of this relationship (low perceived health competence scores causes depression or vice versa) is unclear. Furthermore, as noted earlier, the CES-D is not a diagnostic tool, and should be used only to identify groups at
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risk of clinical depression, who may benefit from further investigation and treatment. This research also supports the view that patients held strong beliefs about the necessity of their medications, yet simultaneously had strong concerns about potential adverse effects. Patients’ beliefs may form the foundations of decisions as to whether medication should be taken as prescribed [28] and these findings have implications for how this can be managed in clinical practice. 4.2. Conclusions Further research is necessary to establish the precise relationship between depression, other psycho-social factors (e.g. beliefs about medications) and adherence, which would provide healthcare professionals with an insight into the relationship between where patients believe the control over their health lies, and adherence with medication. Such an insight has implications for the design of interventions aimed at enhancing adherence rates, and for adoption of the most appropriate patient-healthcare provider consultation style. 4.3. Practice implications A high percentage (41.7%) of patients in the present study with cardiovascular disease reported symptoms indicative of depression. Given that there is emerging evidence to suggest an association between depression and non-adherence, healthcare professionals should consider this when dealing with cardiovascular patients. Such patients may benefit from treatment aimed at alleviating depression, which may in turn, enhance adherence rates. The majority of patients held strong concerns about taking their prescribed medications, and those who perceived their concerns to outweigh the necessity of taking medications, tended to be non-adherent with medication. Concerns may be addressed during concordant consultations with healthcare professionals, or through patient education.
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