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Impact of a Theory-Based Intervention to Promote Medication Adherence in Patients With a History of Myocardial Infarction

Pedrosa, Rafaela Batista dos Santos RN, PhD; Gallani, Maria Cecília Bueno Jayme RN, PhD; Rodrigues, Roberta Cunha Matheus RN, PhD

Author Information
The Journal of Cardiovascular Nursing: 5/6 2022 - Volume 37 - Issue 3 - p E1-E10
doi: 10.1097/JCN.0000000000000854
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Although there have been advances in diagnostic methods and treatment strategies, myocardial infarction (MI) remains a serious disease with important social and economic repercussions.1 The prescription of cardioprotective medications (3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitors [statin], angiotensin-converting enzyme [ACE] or angiotensin receptor blockers, β-blockers, and antiplatelets) is associated with a reduced incidence of acute events, a lower rate of rehospitalization, and increased survival.2,3 However, less than half of all patients with MI benefit from the prevention of other cardiac events because of low patient adherence to medication treatment.4

The recognition of nonadherence and its negative effects have stimulated efforts to develop new interventions, using evidence-based actions aimed at promoting adherence, and then improving outcomes and reducing costs.5 Sidani and Braden6 propose that the process for the design and evaluation of interventions should follow specific recommendations for strategic delivery that consider uniqueness of the patient, the available resources, and the context of clinical practice. In addition, evidence indicates that theory-based interventions are more effective in producing beneficial outcomes related to health-related behaviors, particularly in adherence to medication treatment.7

In recent decades, different theoretical models concerning health-related behaviors have been used to elucidate and optimize medication adherence,7 with intention being the main determinant of the behavior.8,9 Previous investigators have suggested the efficacy of strengthening patient intention for medication adherence.10,11

There is, however, a gap in the intention-behavior relationship, which can be defined as an imperfect relationship between the intention to perform a specific behavior and its implementation, mainly from “good intenders,” those with positive intentions, but who fail in the implementation of the behavior.12 Therefore, planning interventions aimed at supporting patients to translate positive motivation into effective behavior is very important.12,13

The implementation intention strategy was developed based on action performance models; its main objective is to make the individual aware of an adequate future situation (a good opportunity) to promote adoption of the desired behavior.12,13 Some researchers apply this strategy in 2 steps: action plans and coping plans.13 In the first step, the patient is invited to think about the action (target behavior) and then to draft a plan to execute it, specifying time (“when”), environment (“where”), and “how” the behavior must be initiated. The action plan strategy is accompanied by additional components aimed at reducing the gap between the development of plans and the implementation of behavior. The coping plan aims at identifying barriers to implementing the behavior as well as the strategies to overcome them, acting as a “protection” for the target behavior.13

In this intervention, the patient is at the center of the care process, which is characterized as considering the patient's preferences and values, contributing to the promotion of patient compliance and satisfaction.13 The action and coping plans can be applied by different trained health professionals; however, nurses are the appropriate professionals for the development of patient-centered interventions, because they have the longest time in direct contact with the patient and they incorporate educational actions aimed at health promotion.14

Investigators have demonstrated an effective change in different health-related behaviors by using action and coping plan strategies.10,15–17 In the Brazilian context, these strategies were successfully used among patients with a history of coronary artery disease to improve medication adherence among patients in a specialized cardiology clinic, to increase physical activity18 among patients with hypertension, and to reduce sodium intake among patients with heart failure.19 However, the feasibility and potential efficacy of this intervention have not been tested in the clinical context of primary care to improve adherence behavior to cardioprotetive medication among patients with a history of MI.

The Brazilian study in which efficacy of an implementation intention strategy in promoting adherence to cardioprotective medication was demonstrated10 had some limitations. It was conducted in a controlled research context, based only on empirical and theoretical approaches, and the feasibility of the intervention from a patient and a health professional perspective was not assessed.10 Thus, the approach missing was the experiential approach, that is, determining patients' and interveners' perceptions of what would be feasible and acceptable in clinical practice.6 The lack of this element may result in greater difficulty incorporating the intervention in the real world of clinical practice.6

In the first phase of the current study, we used an experimental approach to adapt the action and coping plan strategy to the target population, that is, patients with a history of MI and nurses in primary care units. The results of this phase guided the mode of delivery for the intervention, that is, a written and verbal mode (to develop the action and coping plans for medication taking) lasting no longer than 30 minutes, with face-to-face reinforcement within a 30-day interval.20

In designing our study, we considered the importance of interventions to increase medication treatment adherence that are adjusted to the specific requirements of patients' conditions. The aim of the current study was to evaluate efficacy and feasibility of the implementation intention intervention designed to promote adherence to cardioprotective medications in patients with a history of MI, an intervention whose mode of delivery was designed based on the experiential approach.


Design and Sample

This was a mixed-methods, quasi-experimental study with 3 time points, outlined according to the Transparent Reporting of Evaluations with Nonrandomized Designs21 recommendations and registered with the Universal Trial Number (number: U1111-1189-9967).

The research was conducted in primary care units in a city in the state of São Paulo, Brazil; 45 patients with a medical history of MI were enrolled. Inclusion criteria were as follows: (1) older than 18 years, (2) using cardioprotective medications, and (3) positive intention for medication adherence (assessed by a self-report measure from the instrument “Elicitation of Beliefs Concerning Adherence to Oral Antidiabetic Agents”). Patients presenting with psychiatric illness or mental impairment were excluded. Results from the paired Student t test were used to calculate sample size, considering the objective of comparing the score obtained on the adherence proportion measurement instrument during the 2 assessment times.22


Participants were recruited by the main researcher, and data were obtained during individual face-to-face meetings, in a private environment in the primary care units, and using the following steps. Data collection at baseline (Tb) was conducted by the main researcher. Agreement was obtained from the patient by signature on the consent form; thereafter, information was collected on sociodemographic and clinical characteristics of patients, as well as the measurement of the intention and outcome variables. The primary aim outcome was adherence to medication-taking behavior assessed using the Global Evaluation of Medication Adherence (GEMA) instrument. The secondary aims were blood pressure (BP), heart rate (HR), and lipid profile (total cholesterol and fractions). The intervention was also implemented in Tb.

Action and Coping Plan Intervention

Development of the action and coping plans was carried out in verbal and written form (with construction of the form in duplicate, one for the intervener and the other for the patient), lasting approximately 30 minutes. Each participant was encouraged to develop 3 action plans on “where,” “how,” and “when” they planned to take medication (see example in Table 1). Then, patients were asked to identify the main modifiable barriers that could contribute to not implementing the behavior as planned, as well as the strategies to cope with those barriers (see Table 2 for examples). Afterward, face-to-face reinforcement of those plans was conducted within a 30-day interval, as recommended by the target population, in the experiential approach of this study, described elsewhere.20

TABLE 1 - Action Plans for Adherence to Cardioprotective Medications Adapted From a Previous Study10
Action Plans
 Associate the time of medication with the daily routine, such as bedtime and waking up
 Associate the time of medication with time markers, such as meals (breakfast, lunch, and dinner)
 Associate the time of medication with activities of daily living (eg, after brushing teeth, after shower at night)
 Just at home
 At home and at work
 Associate with mealtimes and take the medication with a glass of water
 Fasting and associated with mealtimes with a glass of water

TABLE 2 - Coping Plans for Adherence to Cardioprotective Medications Adapted From a Previous Study10
Perceived Barriers Coping Plans
Daily life
 Forget the times of medication according to the medical prescription Associate the use of medications with mealtimes
Note the times on the respective medication packages
Request support from a family member
 Lack of family support to remember to take medication Note the times on the respective medication packages
Memorize the names of the medicines with their respective times according to the medical prescription
 Forgetting to buy medicines Note the date of the last purchase and post it in an easily visible place
Count the total number of pills once a week to schedule the purchase of them before they are finished
 Lack of knowledge about the action/purpose of the drugs being used Ask the doctor/nurse for guidance
At work
 Difficulty in reconciling the use of medicines with the work routine Talk to their boss the intervals for using the medications according to the medical prescription
 Forgetting to take medication to work Put medications in your pants pocket, shirt, or bag every day
At leisure
 Forgetting to take medication on outings Prioritize the separation of medicines in sufficient quantities for the trip and put them in the suitcase
 Use of alcohol when taking medication Do not consume alcohol concomitantly with the use of medications

A written copy of the action and coping plans was provided for the participant. They were advised to keep it visible at home to facilitate memorization of the plans.

The second step of the intervention was the reinforcement step (T30). This step was conducted by the main researcher 30 days after Tb. At this step, individual and face-to-face reinforcement was conducted with the participants. The researcher provided a summary of plans developed in the first meeting and analyzed with the patient the difficulties s/he experienced in implementing action and coping plans for the use of cardioprotective medications. Adjustment of plans was made when necessary.

At step 3 (T60), the last meeting, 60 days after Tb, the psychosocial and clinical variables were measured again. A trained nurse not related to the study performed data collection at this step. To ensure impartiality, she had no information about the methodological design of the study. At the end of this step, an individual debriefing was conducted with the participants, guided by 6 reflective questions, to investigate the feasibility of the intervention.

Variables and Measures


This variable was assessed using the first 6 items of the instrument, “Elicitation of Beliefs Concerning Adherence to Oral Antidiabetic Agent,” developed and validated to measure the psychosocial determinants of adherence behavior.23 The items were adapted to the use of cardioprotective medications by patients with a medical history of MI. These 6 items refer to the intention to adhere. The intention score is the arithmetic mean of the 6 items, varying from 1 to 5—the higher the score, the higher the participant's motivation to adopt the behavior. An average score greater than 2.5 reflects a positive intention.

Instrument to Measure Sociodemographic and Clinical Characteristics

An instrument was developed and submitted to a content validity process in a previous study24 and was used to obtain sociodemographic (age, gender, educational level, employment status, family income) and clinical (signs and symptoms related to cardiac disease: precordialgia, dyspnea, dysrhythmia, and syncope) data.

Global Evaluation of Medication Adherence Instrument

The GEMA is a 3-section, self-reported measure aimed at quantifying adherence to medication use.23 The first section consists of the estimation of the proportion of medication intake in the last month. The calculation of the adherence proportion is based on the prescribed dose and the doses actually taken by the patient: [(prescribed doses − doses taken) × 100 / prescribed doses]. It is considered to be an “adequate dose” when there is an agreement of 80% or greater with the prescribed dose and an “inadequate dose” if less than 80% agreement is observed regarding the prescribed dose. The second part consists of 5 items regarding taking medications in terms of distribution of doses according to temporal markers such as fasting, breakfast, lunch, dinner, and bedtime. It is considered to be “adequate care” when the use of medications is in agreement with the recommendations in the prescription (number and frequency of use) and association with time markers (fasting, breakfast, and lunch). If at least one of them is not in agreement, it is considered to be “inadequate care.” The third part is the Global Assessment of Adherence, which considers the proportion of adherence and the care in taking the medication, enabling the initial classification of patients as follows: group 1, adequate dose and care; group 2, adequate dose and inadequate care; group 3, inadequate dose and adequate care; and group 4, inadequate dose and care. Finally, patients classified as group 1 were considered adherent, and those classified in the other groups (2–4) were considered nonadherent.

Blood Pressure and Heart Rate Measurement

Blood pressure measurement was based on the recommendations of the Brazilian Guidelines of the Brazilian Society of Cardiology.25,26 Manual sphygmomanometers with an appropriate cuff for the patient's arm circumference were used to obtain the data. The HR was estimated from the peripheral pulse obtained by manual palpation of the radial artery for 1 minute.

Serum Total Cholesterol (Total COL) and Subfractions (Low-Density Lipoprotein-cholesterol, High-Density Lipoprotein-cholesterol)

A first blood sample was collected at the primary care units, within 5 days of Tb, and another within 5 days of T60. We used values recommended by the guidelines for secondary prevention, with targets Low-Density Lipoprotein-cholesterol less than 70 mg/dL, non–High-Density Lipoprotein-cholesterol less than 100 mg/dL, and High-Density Lipoprotein-cholesterol greater than 40 mg/dL.25,26

Feasibility of Intervention

Feasibility of the intervention refers to the practicality of implementing the intervention6 and was assessed by means of field diary records and the debriefing session conducted at T60. In the field diary, the following information was recorded: (1) number of invited participants and who showed interest in participating; (2) number of eligible and ineligible patients, and the reasons for ineligibility; and (3) number of eligible participants who dropped out and the reasons. In addition, the time spent applying the intervention was evaluated to assess whether the intervention can be used by nurses during work at the primary care units in a quality manner and within a specified period.

In addition, a debriefing section was guided by a semistructured interview that consisted of the following questions: (1) What were the difficulties you found in implementing the action plans, and how did you cope with the barriers? (2) Did you have difficulties adapting the plans into your daily life? Was the intervention approach adequate for you? (3) Was coaching by the nurse useful for developing the action and coping plans? Was the second meeting with the nurse (reinforcement) helpful for adjusting the plans and to preserving plan implementation? (4) If you were invited to participate in this intervention again, would you participate? (5) Do you intend to maintain the use of these plans, even after the research is completed? (6) Do you believe you would be able to develop and implement the action and coping plans on your own? and (7) What do you suggest to facilitate or encourage participation of other patients in this intervention? In addition, participants were encouraged to indicate positive aspects of the intervention, any dissatisfaction with it, and suggestions to facilitate the incorporation of the intervention in actual clinical practice.

Data Analysis

The data were transferred to the SAS - System for Windows program (Statistical Analysis System Institute Inc, Cary, North Carolina), version 9.1.4, for the following analyses. Descriptive analyses consisted of frequency tables, position measurements (mean, median, minimum, and maximum), and measure of dispersion (standard deviation).

McNemar tests were used for comparison of medication adherence measures, overall assessment of adherence, and adherence ratio. A paired Wilcoxon test was used for the comparison of serum cholesterol level, BP, and HR, at the end of the 60-day follow-up. A significance level of 5% was adopted.

Feasibility was assessed using quantitative and qualitative approaches. For quantitative analysis, we measured, in the context of the number of eligible patients, the proportion between the number of patients invited and those demonstrating interest in participating, attrition rates, time spent delivering the intervention, and contextual effects that interfered in its implementation. Qualitative analysis of the data obtained during debriefing was conducted. A simple content analysis27 was used to evaluate the data obtained. The main categories were the central theme of the questions guiding the debriefing.

Ethical Considerations

The study was approved by the local ethics committee (opinion no. 2,239,170 on August 25, 2017). Written informed consent was obtained from all participants.


Sociodemographic and Clinical Profile

The sample was composed mostly of men (62.2%) and was mostly unemployed (75.5%), with a mean age of 63.8 (10.1) years, a mean family income of US $412.00 per month, and an average of 7.1 (3.1) years of education. All patients reported symptoms in the month before the interview, with a mean of 1.2 (1.0) associated symptoms; they used a mean of 3.8 (0.5) cardioprotective medications. The average score of intention for medication adherence was 4.9 (0.8).

Potential Efficacy of the Intervention

The efficacy of the intervention was assessed by means of medication adherence, BP, and HR, in addition to serum cholesterol and subfraction levels. Table 3 presents the results of medication adherence to cardioprotective medication at baseline (Tb) and postintervention (T60).

TABLE 3 - Description of Adherence Measures of Cardioprotective Medications Pre and Post Intervention, in Patients With a History of Myocardial Infarction (N = 45) (Campinas, SP, Brazil, 2018)
Adherence Ratio a Adequacy of Adherence Global Assessment of Adherence
Mean (SD) % Adequate Care b % Adherence c
First meeting (Tb)
 Cardioprotective medications, total 76.8 (16.4) 13.3 13.3
 ACE 69.9 (30.8) 33.3 9.1
 ARB II 75.2 (26.3) 42.3 19.2
 β-Blocker 73.7 (28.3) 15.9 11.4
 Statins 82.5 (28.5) 22.2 13.3
 Platelet antiaggregant 86.2 (23.4) 22.2 13.3
Last meeting (T60)
 Cardioprotective medications, total 92.0 (9.8) 80.0 75.6
 ACE 86.3 (20.9) 91.3 68.2
 ARB II 94.2 (13.2) 80.8 73.1
 β-Blocker 89.6 (18.6) 86.4 72.7
 Statins 93.3 (22.3) 91.1 82.2
 Platelet antiaggregant 97.7 (14.9) 88.9 86.7
Abbreviations: ACE, angiotensin-converting enzyme inhibitor; ARB II, angiotensin II receptor blocker.
aAdherence ratio of medications.
bPercentage of patients who presented adequate care with cardioprotective medications.
cPatient adherence ratio to cardioprotective medications.

An increase in medication adherence was identified, especially with regard to care in taking the medication; a low ratio of patients was found with adequate care in the first meeting (13.3%), with a significant increase (80.0%) after the intervention.

Table 4 shows the distribution of patients based on the adherence ratio, adequacy of care, and global assessment of adherence at Tb and T60.

TABLE 4 - Comparison of Ratio, Adequacy, and Global Assessment of Adherence to Cardioprotective Medications Pre and Post Intervention in Patients With a History of Myocardial Infarction (N = 45) (Campinas, SP, Brazil, 2018)
GEMA First Meeting (T b ) Last Meeting (T 60 ) Difference T 60 − T b P a
n % n %
Adherence ratio Adequate dose 23 51.1 37 82.2 +31.1 .001
Inadequate dose 22 48.9 8 17.8 −31.1
Adeqaucy of adherence Adequate care 6 13.3 36 80.0 +66.7 <.001
Inadequate care 39 86.7 9 20.0 −66.7
Global assessment of adherence Adherence 6 13.3 33 73.3 +60.0 <.001
Nonadherence 39 86.7 12 26.7 −60.0
aMcNemar test.

At the end of follow-up, a significant increase was obtained in the ratio of patients classified as taking adequate doses after the intervention. The difference between the times T60 and Tb was +31.1% (P = .001). There was also a significant increase in the ratio of patients who presented at the adequate care level after the intervention (T60 − Tb difference, +66.7%; P < .001), as well as a significant increase in the ratio of adherence to medication treatment (T60 − Tb difference, +60.0%; P < .001).

There was a reduction in systolic BP values (T60 − Tb difference, −9.1 mm Hg; P < .01) and diastolic BP values (T60 − Tb difference, −8.6 mm Hg; P < .01) at the end of follow-up. Similarly, a decrease in HR was observed after the intervention (T60 − Tb difference, −6.6 bpm; P < .01), as well as a reduction in low-density lipoprotein cholesterol levels (T60 − Tb difference, −6.2 mg/dL; P < .01), as shown in Table 5.

TABLE 5 - Comparison of Mean and Median Blood Pressure, Pulse Rate, Total Cholesterol, and Subfractions, Pre and Post Intervention, in Patients With a History of Myocardial Infarction (N = 45) (Campinas, SP, Brazil, 2018)
First Meeting (T b ) Last Meeting (T 60 ) Difference
T 60 − T b
P a
n Mean (SD) Variation Median n Mean (SD) Variation Median
Blood pressure
 SBP 45 127.1 (15.6) 100–170.0 130.0 45 118.0 (6.6) 110–130.0 120.0 −9.1 <.001
 DBP 45 80.8 (15.1) 60–120.0 80.0 45 72.2 (9.7) 60–90.0 70.0 −8.6 <.001
RP 45 62.9 (8.6) 42–87.0 63.0 45 56.3 (4.9) 45–70.0 55.0 −6.6 <.001
Lipid profile
 Total COL 45 201.7 (70.9) 99–354.0 220.0 45 173.0 (51.5) 98–298.0 178.0 −28.7 <.001
 LDL-COL 45 123.1 (41.0) 38–226.0 111.0 45 116.9 (36.9) 63–300.0 106.0 −6.2 .031
 HDL-COL 45 43.9 (18.0) 30–138.0 38.0 45 41.5 (10.5) 26–66.0 37.0 −2.4 .664
 Triglyceride 45 180.9 (85.6) 84–425.0 169.0 45 154.5 (58.4) 70–312.0 157.0 −26.4 <.001
Abbreviations: COL, cholesterol; DBP, diastolic blood pressure; HDL, high-density lipoprotein; LDL, low-density lipoprotein; RP, pulse rate; SBP, systolic blood pressure.
aPaired Wilcoxon test.

Feasibility of the Intervention

A total of 82 patients demonstrated interest in participating in the study. However, 9 of these patients were ineligible (11%), because they had recent episodes of MI (n = 4), had recent surgeries (n = 4), or had no positive intention for drug adherence (n = 1). Twenty-eight of the 73 eligible patients (38.3%) refused to participate in the study. From the 45 patients finally enrolled in the study, all completed the follow-up, thus reflecting an attrition rate of zero, as shown in Figure.

Adapted flowchart based on the recommendations of Transparent Reporting of Evaluations with Nonrandomized Designs.21

The mean time spent to conduct the intervention in the first face-to-face session was 32 (5.3) minutes. A total of 45 patients participated in the debriefing (T60), and most of them (97.8%) did not find it difficult to think together with the nurse about how, when, or where they would take the medication as prescribed by the physician, or to reflect on barriers and strategies for overcoming them. All participants considered writing down the action and coping plans with the nurse to be important, arguing that it facilitated feasible action plans and adequate strategies for coping with barriers.

The patients also perceived that the personal reinforcement was useful for reviewing and adjusting the plans. All participants admitted the desire to continue the intervention even after the research ended; however, 4.4% of them believed that they would not be able to implement the intervention by themselves in their daily lives, because of their difficulty reading.

Patients indicated positive points in the development and administration of plans. They stated that the intervention (1) individualizes care (n = 44), (2) helps them to remember doses and schedules of cardioprotective medications (n = 35), (3) is easy to perform by themselves (n = 40), and (4) aroused greater interest in their disease, making it possible to reflect on the existing difficulties in taking medications and searching for solutions (n = 40). Finally, they pointed out that the development of plans allowed them to reflect on the necessary changes in their daily lives, to favor medication adherence (n = 30).

The participants offered the following suggestions to facilitate the participation of other patients in the intervention: (1) expand the strategy to patients who use other types of medication (n = 38), (2) guide the patient right after the medical consultation about the intervention and schedule personal reinforcement with an interval of 30 days (n = 25), (3) apply the intervention to patients with other types of chronic diseases (n = 18), (4) include the participation of a family member who aids in the use of the medications (n = 20), and (5) increase the number of visits for patients who need closer follow-up (n = 11). Only 4 patients did not present any suggestions.


In this study, we present important findings about a theory-based intervention with evidence for potential efficacy and feasibility when applied to patients with a positive intention to adhere to cardioprotective medications. We observed a significant reduction in nonadherence rates, which may have influenced the positive clinical end points, such as the improvement in BP, HR, and lipid profile in patients experiencing the intervention, despite the small number of participants.

Among the 45 study participants, 86.7% were classified as nonadherent to pharmacological treatment at Tb, and low adherence was mostly observed regarding the use of ACE, which had the lowest percentage of patients classified as adherent (9.1%). These data corroborate the literature that showed reduced rates of adherence. Rates were 62.0% for antiplatelet agents, 40.0% for β-blockers, 49.8% for ACE or angiotensin receptor blockers, and 66.5% for statins.28 However, after the implementation of the intervention, adherence increased and the percentage of patients classified as adherent to cardioprotectors was 75.6%, and 68.2% were adherent to ACE, demonstrating that the strategy is effective in changing behaviors of nonadherent patients.

The increase in the number of patients classified as adherent is due to the optimization of both the proportion of medication use and the care taken in the use of medication. The main inadequacies found among the participants were delays in use of the medication, ingestion with inappropriate liquids (alcoholic beverages, soft drinks, and juices), and ingestion not associated with temporal markers. Improvements in the use of the right dose, adequate timing of intake, and association with time markers as a result of the intervention contributed to a better score on the GEMA. Similar findings point to the efficacy of the intervention for improving medication adherence in patients with epilepsy,29 coronary artery disease,10 and hypertension.30

The data suggest that improvement of global adherence to cardioprotective medications may have contributed to the achievement of therapeutic goals regarding control of BP, HR, and maintenance of cholesterol rates within appropriate limits.25,26,31 When developing action and coping plans, patients stated strategies for behavior change that could be performed in their daily lives, enabling an evolution from the point of making the decision to taking action, to the actual implementation of the target behavior.13

Feasibility is the degree to which participants agree to participate, complete, and comply with all steps of the intervention.6 Although the participation rate in this study was higher than the average (61.6%) among eligible patients, it is still lower than the rates found in studies that evaluated the feasibility of interventions.32,33 A possible explanation for such difference may be related to the nature of the intervention or the target population. A total of 28 eligible patients (38.3%) refused to participate in the research, and the reasons given by these individuals were physical limitations to locomotion, inability to leave work to participate in meetings, and the need to care for grandchildren or spouse. Therefore, none of the reasons identified were related to the nature of the intervention.

All participants completed the steps of the study; therefore, the dropout rate was zero. This result was better than the values found in studies that evaluated dropout during the implementation of interventions.34,35 Dropout was recognized as a factor that threatens internal validity and reduces statistical power.36 In this study, the dropout rate can be explained by the measures adopted to facilitate the mode of intervention delivery, such as choice of meeting dates based on patient preference, and usually on days when the patient would already be at the primary care unit (eg, for laboratory tests or medical appointments).

The mean time for administering the strategy was similar to that suggested by study participants who applied the experiential approach in the adequacy of this intervention20 and similar to the time reserved for nursing appointments in the primary care units. No difficulties were found because of contextual effects, which can be explained by the fact that the researcher chose periods in which the primary care units had fewer appointments or scheduled procedures and, therefore, greater availability of rooms and equipment. Therefore, the intervention proved to be achievable in clinical practice, because it previously presented mean participation rates among eligible patients and zero friction.

The results of the debriefing performed at the end of the intervention showed the positive aspects of this strategy, and its feasibility was supported by patients. The main positive aspects refer to the perception that the intervention is effective, enables patient understanding of the importance of medication adherence, improves the quality of care, and is easy to apply. Similar results were demonstrated in previous studies.37,38 In addition, research participants reported satisfaction with the experience during the intervention. As evidenced in previous studies, patients reported that it was not difficult to propose the plans.10,19 The positive attitude of the patients regarding the intervention may have contributed to the high attendance at meetings during the data collection phase and to the improvement in medication adherence, lipid profiles, BP, and HR. Participants who consider an intervention to be feasible usually implement it in their daily lives, which in turn increases the likelihood of achieving the intended results.37

Finally, this study demonstrated that the theory-based intervention presents evidence of potential for efficacy and feasibility when applied to patients with positive intention for behavior change and with low adherence to cardioprotective medications, because a significant reduction in nonadherence rates and improvement in BP, HR, and serum cholesterol values were observed by the patients using the strategy.

These results provide an understanding of how best to address medication nonadherence, using action and coping plans, by means of an individual approach for the patient with a history of MI in a private setting, in a written and verbal mode (for the development of the action and coping plans for taking medication), lasting approximately 30 minutes, and with face-to-face reinforcement at a 30-day interval. Therefore, these findings represent a basis for implementation, evaluation, translation, and transfer of the intervention to clinical practice. Further studies are recommended to assess the effectiveness of the intervention in real clinical conditions and with a longer follow-up time, to also monitor the maintenance of behavior change.

Limitations and Strengths

The limitations of this study relate to the small sample size, which prevents generalization of the results. However, these results are important to guide further experimental and pragmatical studies, whose results could be generalized. Another limitation is the fact that the times scheduled for meetings during the data collection phase occurred in periods with fewer activities at the primary care units, which may have decreased the interference of contextual factors in implementing the intervention. A strength of the study was that patients enrolled had an average of 7.1 years of education. Patients receiving care from public primary care in Brazil are characterized by a low level of education and health literacy. There was evidence that the intervention is potentially effective for this population. One factor contributing to this result is probably related to the experiential approach conducted in the first phase of this study, allowing for adaptation of the intervention to the expectations of the target population.


This study provides evidence that this theory-based intervention has the potential to increase adherence to cardioprotective medication in patients with a history of MI and that increased adherence may contribute to reduction of BP and HR, and better control of lipid profiles. Moreover, feasibility was supported because more than half of the patients considered eligible accepted to participate in the study. These participants completed all stages of the study and found the intervention easy to apply; the time spent on implementation was similar to that proposed by the target population.

What’s New and Important

  • This study provided a theory-based intervention, with high feasibility for clinical practice.
  • The strategy demonstrated potential efficacy regarding adherence behavior for cardioprotective medications.
  • This intervention does not require major changes in the nurses' routine, with low cost to the health system and ease of application.


The authors thank all the patients who participated in the study.


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behavior; intention; medication adherence; nursing

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