Factors associated with variation in secondary prevention medication use after stroke
Stroke is an important cause of death and disability. Once a person has had a stroke or transient ischaemic attack (TIA), they have a high chance of having another, and this risk can be reduced by taking stroke prevention medications. Medications to prevent recurrent stroke include statins to lower cholesterol, medications to lower blood pressure, and anti-platelets or anticoagulants to reduce the risk of clotting, yet many patients do not take them. In this thesis, I investigated which stroke and TIA survivors are missing out on stroke prevention medications. First, a systematic review and meta-ethnography combining 15 studies and including 350 patients demonstrated that stroke patients are diverse and can have many challenges which make medication-taking difficult. Patients have different beliefs about their medications, about stroke and about health which influence whether they take their medications. Social and professional support can make medication-taking easier, and should be tailored to the individual’s challenges and beliefs. Second, a systematic review of 41 observational studies (125,746 patients) demonstrated 28 factors that are associated with altered levels of medication-taking. The strongest evidence linked three cardiovascular co-morbidities (dyslipidaemia, hypertension and diabetes), alongside male sex, higher income, pre-stroke use of medications, stroke unit care and living with others with medication-taking. Anxiety and disability were linked with lower levels of medication-taking. The studies were highly varied, both in their populations and how they defined taking medications. Additionally, some bias, especially reporting bias, was present. Third, a population-representative cross-section of 45,521 UK stroke or TIA patients >=25 years was extracted from primary care routine data. This sample confirms that, when indicated, only 72% of stroke and TIA survivors use statins, 83% use antithrombotics and 80% use anticoagulants. Likewise, only 75% use antihypertensives, and 36% have documented blood pressure control. Cardiovascular co-morbidities were strongly associated with higher levels of medications use, whereas some mental health co-morbidities were associated with lower levels (specifically: alcohol problems, dementia, learning disability, and a history of psychosis). Women, patients at the extremes of age (younger than 55 and over 85), and patients with relatively infrequent GP practice consultations were all less likely to use preventative medications. This thesis provides a model to explain why certain groups of stroke and TIA survivors are less likely to take stroke prevention medications. It describes many of these groups and suggests policies and interventions to support them. It also suggests how and why research and clinical databases should include more variables, such as patient belief and social support factors, which are currently systematically disregarded.
electronic health records, medication adherence, medication persistence, medication-taking, multimorbidity, secondary prevention, stroke, stroke prevention
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