Adherence to medications for the secondary prevention of stroke

Al AlShaikh, Sukainah (2017) Adherence to medications for the secondary prevention of stroke. PhD thesis, University of Glasgow.

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A variety of evidence based pharmacological strategies are recommended to reduce the risk of stroke recurrence. The exact medications used will differ dependent on stroke aetiology and typically include antithrombotic, blood pressure lowering and lipid lowering strategies for ischaemic stroke and blood pressure lowering strategies for haemorrhagic stroke. Non-adherence to secondary preventative medications after stroke is common and is associated with poor outcomes.
Failure to adhere to medication regimens can be intentional, whereby the patient deliberately decides not to take medication or can be unintentional. For example, patients with limited financial resource or cognitive problems may struggle to adhere to the complex secondary prevention regimens often required post stroke. In turn, several factors contribute to these types of non-adherence. For example, intentional non-adherence may arise following an adverse event or be due to motivational factors whereas unintentional non-adherence can be due to impaired memory function. Stopping medication after stroke may be entirely reasonable if the clinical condition and balance of risks and benefits has changed. Understanding factors associated with adherence could inform strategies to improve it and improve clinical outcomes.
Numerous strategies exist to promote adherence but the feasibility and extent of resulted improvement in stroke patients is unclear. Strategies include educational, motivational or practical interventions; however, a combination of these is usually needed in order to reach sufficient improvement.
This research aimed to establish the extent of non-adherence to secondary preventative medications after stroke, explore factors associated with poor adherence and describe interventions used to enhance adherence to preventative medication after stroke.
The first chapter covers a thorough literature review of the evidence-based recommendations for the secondary prevention after stroke and looked generally at reported rate of adherence and reasons for non-adherence. Systematic reviews and meta-analyses were used to identify predictive factors of non-adherence in chapter 2 and strategies used to enhance adherence to secondary preventative medication after stroke in chapter 5. Both followed PRISMA guidelines in designing the search criteria and reporting of the results. Also, chapter 3 contains a descriptive analysis of a retrospective data of stroke patients enrolled into clinical trials including patients’ characteristics and their medication intake behaviour in the first 90 days after stroke. Chapter 4 investigated the factors associated with non-adherence to secondary preventative medication within the population described in chapter 3 using survival analysis. Then, a pilot study of a promising intervention in post-stroke population was performed based on the findings of the systematic review of effective interventions that enhanced medication adherence in stroke population and the findings of this study are presented in chapter 6.
Chapter 2: This systematic review identified several factors in different categories that were associated with adherence to secondary preventative medication after stroke. These involved patient related factors such as having concerns about treatment, socioeconomic factors such as presence of carer, health related such as co-morbidities and disability, medication regimen factors including polypharmacy and cost of medication, caregiver factors like adequate communication and continuity of care, or stroke related factors including severity of stroke and stroke subtype. However, none of the factors included in meta-analyses was of significant effect on medication adherence; which is possibly due to heterogeneity in included studies. Prevalence of medication non-adherence in included studies was 32.8% of overall medication regimen (95% CI: 32.2-33.3%).
Chapter 3: 10304 Patients were included in the analysis; 54.5% were males and the mean age of participants was 69.4 ± 12.4 years. Of secondary preventative medication prescriptions, 21.3% of patients received anti-coagulants, 64.1% received anti-platelets, 18.2% received hypoglycaemic drugs, 17.9% received lipid-lowering drugs and 56% received Blood Pressure (BP) lowering drugs. Adherence rate was 88% to anticoagulants, 81.3% to anti-platelets, 68.9% to hypoglycaemic drugs, 86.7% to lipid-lowering agents and 78% to BP lowering drugs. Patients in this analysis received a mean of 7.1 (SD, 7) or a median of 5 (IQR, 3 – 9) medication per day.
Chapter 4: In Cox-regression survival analysis using multivariable analysis, frequent factors associated with non-adherence to secondary preventative medication classes. To anti-platelets medication- female gender, atrial fibrillation, ischaemic heart disease, polypharmacy (treatment with > 5 drugs), cortical involvement, recurrent ischaemic or haemorrhagic stroke or bleeding while on treatment all associated with non-adherence. To anti-coagulant drugs- more severe stroke, smoking, polypharmacy, bleeding and recurrent ischaemic or haemorrhagic stroke associated with less adherence. To lipid-lowering drugs- non-white ethnicity, more severe stroke, smoking, congestive heart failure, previous stroke and recurrent ischaemic or haemorrhagic stroke all associated with decreased adherence. To BP lowering drugs- more severe stroke, smoking, previous stroke, thrombolysis treatment at baseline, cortical involvement in stroke, syncope, hypotensive episodes, and recurrent ischaemic or haemorrhagic stroke associated with non-adherence; whereas history of hypertension and polypharmacy associated with better adherence.
Chapter 5: Interventions that involved patient education and counselling about medication at hospital discharge, provided a computerised educational program regarding risk factors management after stroke, encouraged self-care after stroke, motivated the patients to modify health behaviour or provided cues or reminders to take medication lead to significant improvement in adherence to secondary preventative medication after stroke. When combined in meta-analysis for each medication class, interventions significantly enhanced adherence to antithrombotic drugs (anti-coagulants and anti-platelets), lipid-lowering drugs and BP lowering drugs but not to the overall secondary preventative medication regimen.
Chapter 6: Ten participants were recruited to this pilot study, half of which were randomised to the intervention group i.e. received daily reminders. Mean age of participants was 59.6 ± 14.7 years and eight were males. All patients completed the study visits (baseline, 1-month and 3-months visits) where they were given an education session at baseline and medication adherence was assessed in each visit using a validated medication adherence scale. At 3-months post intervention, adherence to secondary preventative medication improved for two participants in the intervention group but reduced in two participants in the control group.
Studies in this thesis quantified rate of adherence to secondary preventative medication after stroke in real-life and clinical trials stroke patients. These studies added to the previous knowledge that non-adherence was common after stroke with around 30% of all patients discontinued treatment. Many factors were identified and associated with reduced adherence in stroke population. This finding could inform stroke clinicians to give extra care to those at risk of stopping secondary prevention measures. In addition, various strategies found by this research to be useful in improving medication adherence in stroke population. Such interventions need to be included in after stroke care. There is a major need for larger studies to investigate what are the best strategies to enhance adherence to medication after stroke.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Due to copyright issues this thesis is not available for consulation.
Keywords: Stroke, secondary, prevention, medication, adherence, TIA.
Subjects: R Medicine > RM Therapeutics. Pharmacology
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Supervisor's Name: Dawson, Dr. Jesse and Walters, Prof. Matthew
Date of Award: 2017
Depositing User: Dr Sukainah Al AlShaikh
Unique ID: glathesis:2017-7847
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 20 Jan 2017 13:33
Last Modified: 20 Feb 2019 09:07

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