|Year : 2019 | Volume
| Issue : 3 | Page : 122-128
Predictors of nonadherence to antihypertensive medications among stroke survivors in Benin City Nigeria
Francis E Odiase, Judith E Ogbemudia
Department of Medicine, College of Medical Sciences, University of Benin, Benin City, Nigeria
|Date of Submission||10-Jul-2019|
|Date of Decision||29-Oct-2019|
|Date of Acceptance||25-Nov-2019|
|Date of Web Publication||04-Feb-2020|
Dr. Francis E Odiase
Department of Medicine, College of Medical Sciences, University of Benin, Benin City
Source of Support: None, Conflict of Interest: None
Background: Hypertension is the single most important modifiable risk factor for developing stroke and its recurrence. Evidence suggests that antihypertensive treatment rates following stroke remain poor worldwide and non-adherence to secondary preventive medication is a disturbing clinical problem associated with recurrence and poor outcomes. Aim: The aim of this study was to determine the predictors of non-adherence to antihypertensive medications among stroke survivors 3 months after their stroke. Materials and methods: This was a cross-sectional study, involving stroke survivors attending the out-patient neurology clinic at the University of Benin Teaching Hospital, Benin City, 3 months after their stroke. Demographic and clinical characteristic were obtained, with a questionnaire, while medication adherence was measured by pill count method. In the final logistic regression analysis, the independent variables were age, gender, educational status, marital status, modified Rankin scale, polypharmacy, and types of stroke while medication non-adherence was the dependent variable. Results: One hundred and twelve stroke survivors participated. There were 58(51.8%) males and the mean age was 72(12) years. The non-adherence rate in this study was 57.1 %(64/112). The significant predictors of non-adherence to antihypertensive medications were the female gender (P = 0.009), severe disability (P = 0.003), the older participants (P = 0.004), and polypharmacy (P = 0.002). Conclusion: Non-adherence to antihypertensive drugs following stroke was observed in our study, which would affect blood pressure control leading to stroke recurrence. To prevent recurrent strokes, stroke survivors must adhere to their antihypertensive drugs, while involving patient and family members in decision making with regards to treatment plans.
Keywords: Anti-hypertensive drugs, hypertension, non-adherence, recurrent stroke, secondary prevention of stroke
|How to cite this article:|
Odiase FE, Ogbemudia JE. Predictors of nonadherence to antihypertensive medications among stroke survivors in Benin City Nigeria. Sub-Saharan Afr J Med 2019;6:122-8
|How to cite this URL:|
Odiase FE, Ogbemudia JE. Predictors of nonadherence to antihypertensive medications among stroke survivors in Benin City Nigeria. Sub-Saharan Afr J Med [serial online] 2019 [cited 2022 May 17];6:122-8. Available from: https://www.ssajm.org/text.asp?2019/6/3/122/277779
| Introduction|| |
Stroke is a leading cause of death and disability worldwide, with 85% of global deaths from stroke occurring in the developing countries.. About 25% of all stroke survivors would have a recurrent stroke and they also have a 15-fold increased risk of reoccurrence of stroke compared with the general population. Mortality and major disability are worse still after a recurrent stroke. Hypertension is the single most important modifiable risk factor for developing stroke recurrence. Hypertension is also associated with worsened death and mortality outcomes after strokes. Established treatments for preventing recurrent strokes include longterm use of medications such as hypertension drugs in survivors of stroke, in addition to lipid lowering agents and antithrombotic therapy for those with ischemic stroke.
Secondary preventive strategies utilization has been found to result in 80% reduction in the risk of stroke recurrence, vascular events, or death while a good blood pressure control has been proven to reduce stroke recurrence by 30% to 40 %.
Evidence suggests that despite this, treatment rates following stroke remain poor worldwide and non-adherence to secondary preventive medication is a disturbing clinical problem , associated with recurrence and poor outcomes.
Several studies have reported that secondary preventive drugs are usually stopped or interrupted,,, and estimating non-adherence of about 50% to prescribed medication for chronic diseases. In Nigeria the medication non-adherence rate of 32.7% to 66.7% to antihypertensive drugs among hypertensive individuals have been observed.,,,,,, The World Health Organization (WHO) has classified the predictive factors of non-adherence into five domains, including patient-related factors, socioeconomic-related factors, therapy-related factors, health system and health care team-related factors, and the condition-related factors.
Many factors have been attributed to poor adherence to secondary medications among stroke survivor. These include functional disability, dependence on others, lack of carers, older age, cognitive impairment, preferences and beliefs about drugs, costs of medications, regime-related factors, poor communications with healthcare providers, other chronic co-morbid conditions, polypharmacy, adverse effects, complex regimen, and interactions. ,,
Majority of antihypertensive drug adherence studies in Nigeria have been done on persons who are primarily hypertensive.,,,,,, We are not aware of any study in the south region of Nigeria that has looked at the non-adherence of stroke survivors to antihypertensive medications. This study hopes to determine the predictors of non-adherence to antihypertensive medications among stroke survivors 3 months after their stroke. Understanding the factors associated with non-adherence could inform strategies to improve it and reduce recurrent stroke rates.
| Materials and methods|| |
This was a cross-sectional study done in the outpatient department, neurology clinic at the University of Benin Teaching Hospital, Benin City, from January 2017 to September 2018. The study involved stroke survivors attending the outpatient clinic for follow-up care, who were consecutively recruited. Eligible patients were those above 18 years, who had a stroke with confirmed cranial CT brain scan, and are on secondary preventive medication including antihypertensive. Ethical approval was obtained from the ethics and research committee, of the University of Benin Teaching Hospital, Benin City. A structured questionnaire was designed for this study, and it was tested in a pilot study with ten stroke survivors.
The stroke survivors were at discharge invited and asked to participate in a face-to-face interview at 3 months after their stroke. They were to come along with their discharge prescription papers and the sachets of all medicine used during this 3-month period. This particular assessment day would fall on their usual clinic day. Those who agreed to participate were reminded on the clinic day prior to the exact day while some had phone-call reminder. Proxies were used for severely aphasic and cognitively impaired patients. Baseline demographics including, gender, age, educational status, occupation, the type of stroke, numbers of medications on, and medicines prescribed at discharge were gotten from the medical records. Participants were considered to be on antihypertensive when on the following drugs, diuretics, B-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, vasodilators, or methyldopa for hypertension.
The modified Rankin scale was used to assess patient’s disability level, when they had presented 3 month post-stroke for the study. The mRs is a 6-point ordinal hierarchical scale that has been widely adopted as a measure of disability in stroke studies. It has five different grades of disability, from grade 0 for no symptom at all, grade 1 when there is symptom but no significant disability, grade 2 when slight disability, grade 3 when moderate disability, grade 4 when moderately severe disability, grade 5 when severe disability, requiring constant nursing care, and grade 6 for death. In this study, the mRs was dichotomized into none/slight disability (grade < 3) and moderate/ severe disability (grade ≥ 3).
Medication adherence was measured by pill count method. , The pills/sachets used during the 3-month period after stroke were sorted out, separating the antihypertensive medications from the other drugs and carefully counted by the authors. Adherence percentage was calculated by the number of pills absent in a given period (3 months in this study) divided by the number of pills prescribed by the physician in the same period. Participants with a percentage score equal to or greater than 80% were said to be adherent, while those with percentage score less than 80% were considered non-adherent to their medications. From the pill sorting those on several medications (polypharmacy) were determined and dichotomized into polypharmacy, <5 drugs, and ≥5 drugs. Those with non-adherence (<80%) were asked to give reasons for this non-adherence.
The statistical analysis was performed using SPSS version 21. Continuous variables were presented using means, median, standard deviation, and range with comparison using Student’s-test. Frequency and percentages were used to summarize categorical variables with chi-square to assess the association between variables. Medication non-adherence was the dependent variable while age, gender, educational status, marital status, modified Rankin scale, polypharmacy, and types of stroke were the independent variable in the final logistic regression analysis. All tests of hypothesis were two tailed with P < 0.05 level of significance
| Results|| |
One hundred and seventy-two stroke patients who were on admission in our stroke wards at discharge were invited to participate in this study, 3 months after. A total of 22 declined participation, 15 who had initially promised to participate did not come. A total of 23 who were presented could not participate, because of concurrent illness. We eventually recruited and assessed 112 stroke survivors. There were 58 (51.8%) males and 54 (48.2%) females. The mean age was 72(12) years, with age range of 35 to 90 years. Majority (53.6%) of the participants were less than 65 years old. About 60% of the participants had both secondary and tertiary educational qualifications. Regarding marital status 59% of our stroke survivors were married. A total of 70% had ischemic stroke, while 30% had hemorrhagic stroke. Moderate to severe disability was found in approximately 50% of the participants while 60% of the participants were on several medications (poly-pharmacy) [Table 1].
|Table 1 Demographic and clinical characteristics of 112 stroke patients on antihypertensive medications 3 months after a stroke|
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The non-adherence rate in this study was 57.1% (64/112). Females were more non-adherent to their medications compared to males (64.8% versus 50.0%, P = 0.11), while participants with lower educational status were more non-adherent compared with those with higher educational status (64.4% versus 52.2% P = 0.20). Participants with moderate to severe disability were significantly non-adherent compared with those with none to slight disability (70.9% versus 43.9% P = 0.004). The older stroke survivors (>65 years) were more likely to be non-adherent to antihypertensive compared with those <65 years (69.2% versus 46.7% P = 0.016) while participants on several medications were significantly more non-adherent compared to those on fewer drugs (66.2% versus 43.2% P = 0.016). There was no change in the pattern of non-adherence on the variable marital status (married; single, 57.6% versus 56.5%) and the stroke types (hemorrhagic; ischemic 58.2% versus 56.5%) [Table 2].
|Table 2 The association between the demographic and clinical characteristics of stroke participants and their adherence to antihypertensive drugs 3 months after a stroke|
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The significant predictors of non-adherence to antihypertensive medications were the female gender (OR 1.05, 95% CI 1.97 to 111.4, P = 0.009), severe disability (OR 13.5 95% CI 2.5 to 73.0, P = 0.003), the older participants (OR 10.4 95% CI 2.10 to 51.7 P = 0.004), and poypharmacy (OR 14.6 95% CI 2.69 to 79.4 P = 0.002). Educational status, marital status, and type of stroke were not predictive of non-adherence to antihypertensive medications [Table 3] and [TABLE 4].
|Table 3 Reasons for non-adherence to antihypertensive drug among stroke survivors 3 months after a stroke|
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|TABLE 4 Multiple logistic regression analysis of predictors of nonadherence to antihypertensive drugs among stroke survivors|
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The cost of medications (70%), not aware that the drug was meant for hypertension (65.6%), and prescribed drugs not available in their locality (56.3%) were the main reasons given for non-adherence by participants.
| Discussion|| |
Medication adherence continues to decline even after a fatal event such as a stroke. The WHO defines adherence to long-term therapy as the extent to which a person’s behavior, taking medication, following a diet, and/or executing lifestyle changes corresponds with agreed recommendations from a health care provider. Despite the availability of effective antihypertensive medications, poor adherence has been identified as a main cause for poor blood pressure control and it is known that high blood pressure increases the risk of stroke re-occurrence.
We found that over half (57.1%) of the stroke survivors 3 months after their stroke were non-adherent to their antihypertensive drugs. Previous studies on antihypertensive medication among hypertensive individuals had non-adherence rates from Nigeria and Ghana (32.7% to 66.7%),,,,,,, Kinshasa DRC (54.2%), which are similar to our study. An Ethiopian study had a much lower non-adherence rate of 26%, while studies from India had rate of 44.6% to 49.2%. These variations in non-adherence are explained by the differences in population studied and the measure used for assessing adherence. Among stroke survivors reported non-adherence rate ranged between 11.3% and 45.2%.,,
Our respondents had given several reasons for their non-adherence to their antihypertensive medications from high cost of drugs, non-available in the pharmacy, to poor communications from health providers.
We found that the older stroke patients were more likely to be non-adherent to antihypertensive compared with the younger stroke patients. Age and non-adherence in stroke survivor’s studies have had contrasting findings with some revealing that the older stroke patients are non-adherent ,, while other had differing observations with younger aged stroke patients associated with medication non-adherence.,, This non-adherence with aging could be due to the presence of multiple co-morbidities in the elderly in addition to forgetfulness. Many older participants are no longer gainfully employed with slim financial resources and little information. This is worrisome since increasing age is an established risk factor for recurrent stroke added to the challenge of medication non-adherence.
Our study found that about 65% of the female stroke survivors were non-adherent to their antihypertensive and that the female gender was a strong predictor of non-adherence to antihypertensive, compared to the male stroke patient. Similar findings were revealed in other studies, although some found the males stroke survivors non-adherent. The female non-adherence might reflect the sorry economic status of women, the much greater support and care enjoyed by the male in contrast to the female folks, or the belief system of the female patient that is much influenced by their spirituality.
We did not find any association between marital status and non-adherence to antihypertensive drugs. The married state, which is a form of family support, social network, or carer presence, were more likely to be non-adherent although not significant. Other studies had divergent observation with presence of family support predictive of adherence to medications.,, It is possible that the spouses of these stroke victims are equally elderly and the care of their sick partners may be challenging. About 30% of our respondents had attributed their non-adherent behavior to frequently changing their carers. Those stroke survivors whose carers fluctuate between housemaid, spouse, children, or close neighbors would at some point in time not be conversant with medication schedule or importance. Other studies have equally observed factors in patient caregiver relationship which are predictive of non-adherence to included language barrier, lack of trust, no continuity of care, no information regarding drug regimen. ,,,, The level of information, dedication, and commitment of the carer not just their presence should be the area of emphasis in medication adherence.
There was no significant association between educational status of patient and their adherence to antihypertensive medications in this study. Although we had observed that those with no formal and primary education were more likely to be non-adherent to their antihypertensive medication compared with those with higher educational status, this was not predictive of non-adherence. Other studies have also observed no association between educational status and adherence.,, While others have shown that some sort of education did enhance compliance., It is possible that with the stroke events and some dependence on a carer the patient educational status would not be of much influence to medication adherence.
It was observed that the majority of stroke survivors with moderate to severe disability (mRs > 3) were more likely to be non-adherent to medication and also predictive of non-adherence. More severe disability was also observed as a predictor for non-adherence in other studies,,,,, although some found that compliance was improved by worsened disability.,, The severely disabled is unable to self-administer might also be cognitively impaired with forgetfulness is completely dependent on someone-else and might have lost the source of livelihood, which would explain their situation. Conversely the very disabled patient might engender greater concern from family which would translate to adherence to antihypertensive medications.
About 60% of our participants were found to be on several medications. Those on polypharmacy were more likely to be non-adherent and this was significantly predictive for non-adherence compared with those on fewer drugs. Other studies have also had similar findings.,,, We also observed that in the non-adherent stroke survivors, that in addition to concern about having to take many medications, side effects from these medications, cost of medications, none-available in their rural locality, lack of confidence or belief resorting to alternative medications, and not informed about the rationale of the drugs were responsible for their non-adherent behavior. Some of these medications prescribed are familiar drugs and for some in spite of having used them they are down with stroke but the details of usage is not ascertained. Similarly cost,, concerns about the medications,,,, number, and frequency of drugs prescribed,,,, no benefit of treatment in using the drug have all been reported to predict non-adherence. On the contrary other works found that positive belief about medications and knowing the consequences of not using their medication,,, understanding the medication rationale,,, initiation of drugs at discharge all enhanced adherence to medication. Hence determining the nature of their adherence would help avert a recurrent stroke.Seventy percent of our study stroke survivors had suffered an ischemic stroke, but we did not find any association between stroke type and adherence to antihypertensive medications. Stroke types were predictive in other studies, for non-adherence to antihypertensive drugs, including ischemic, cardio-embolic, and hemorrhagic strokes.,,,, The severity of the stroke or the resultant disability seemed more relevant than the type of stroke in predicting adherence.
The main limitation was our inability to ascertain if the medications used were all brought or if additional ones were added to it from other sources, and secondly not all the medications were in sachets making counting difficult.
| Conclusion|| |
To prevent recurrent strokes with its poor outcome, patients should be placed on secondary preventive medications. To ensure that patient adhere to their drugs in this case antihypertensive drugs, multiple interventions have been recommended including,,,,,, involving patient in decision making with regards to treatment plans. Patients, spouses, children, or carers should be informed about stroke, secondary preventive medications, and rationale for prescribing drugs, side effects, ally anxiety about misbelief about drugs, and ensuring convenient regimen with cues for patient. Health-care-providers should be accessible with ample time allotted for follow-up visit in addition to sending reminder using text messages. Future research should focus on methods to better prevent medication non-adherence using intervention reported to be effective.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [TABLE 4]