Management of hypertension in Australian general practice

Abstract

Hypertension affects 6 million Australians and is the most common condition seen in primary care. In 2015, elevated blood pressure was responsible for 5.8% of Australia's total burden of disease and is one of the most prevalent risk factors for cardiovascular disease. In addition to lifestyle modification, effective antihypertensive therapy is available to manage hypertension. Rather than managing patients based on their blood pressure alone, guidelines recommend treating patients according to their absolute cardiovascular disease risk. However, international evidence indicates that adherence to guidelines and medication is poor. In Australia, there has been limited research conducted in general practice to understand the management of hypertension and alignment with guidelines. Four distinct projects contributed to the main aims of this research: to investigate the management of hypertension in primary care and to inform the design of cost-effective interventions for improving blood pressure control. The first two projects involved cross-sectional analyses of de-identified electronic health records of 1.2 million patients attending 650 general practices across Australia (MedicineInsight). The first analysis found that the prevalence of hypertension among adults was 39.8% (95% CI: 38.7–40.9), with prevalence increasing with age and greater in males than in females. Furthermore, only 54.9% (95% CI 54.2–55.5) of patients with a diagnosis of hypertension had controlled blood pressure (BP <140/90mmHg). According to guidelines, patients aged 45–74 years are eligible for cardiovascular disease risk assessment. The second analysis found that only 51.0% (95% CI: 48.0–53.9) of these eligible patients had data recorded in their medical records to calculate their risk. Prescribing of antihypertensives was similar across all cardiovascular disease risk categories – low risk=63.3% (95% CI: 61.9–64.8); moderate risk=61.8% (95% CI: 60.2–63.4); high risk=57.4% (95% CI: 55.4–59.4). An existing cost model was adapted to use population and electronic health record data to estimate the health and financial costs of uncontrolled hypertension through increased cardiovascular disease risk. Cost analysis demonstrated a potential reduction of 25,845 cardiovascular events over 5 years with an associated cost saving of AUD 179 (in 2019–20) million with improved BP control. Poor medication adherence is a critical contributing factor to inadequate blood pressure control. Therefore, a systematic scoping review of interventions using behavioural economic concepts to improve medication adherence in patients with chronic conditions was conducted. The review highlighted the importance of targeting non-adherent patients, understanding their reasons for non-adherence, and providing reminders and feedback to patients and physicians as critical factors in improving medication adherence. This thesis highlights that blood pressure control in primary care remains poor, and compliance with hypertension management guidelines is suboptimal. With substantial costs attributed to uncontrolled blood pressure, investments in interventions to address poor blood pressure control are essential. The findings from the systematic scoping review provide a foundation for designing interventions to improve adherence to blood pressure medications. In addition, the findings on prevalence and costs provide the basis for early economic evaluations to inform the expected value of alternative intervention options.