Use of evidence based pharmacotherapy for cardiovascular disease in Scotland

Background: Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality worldwide. Clinical guidelines, based on the results of randomised controlled trials, state that effective secondary prevention therapies should be prescribed following a diagnosis of particular CVD unless there are contraindications. Although evidence shows that use of evidence based pharmacotherapies after diagnosis of CVD reduces mortality and disease progression, many inequalities exist in prescribing practice. Many studies have documented that women and the elderly are less likely to receive evidence based therapies than men and the young, respectively. Greater socioeconomic deprivation has also been shown to be associated with lower rates of prescribing of therapies. However, prior studies have all focussed on one particular CVD or failed to adjust for confounders. Also, few studies have examined trends in the prescribing of evidence based pharmacotherapies over time and documented whether prescribing inequalities are static, narrowing or widening. This project aims to describe the pharmacotherapy received by patients with CVD in Scotland, and to describe the factors associated with prescribing of evidence based pharmacotherapy. Methods: In this retrospective cohort study I examined a linked database of primary care records (Continuous Morbidity Records) and secondary care records (Scottish Morbidity Records) covering 238064 individuals in Scotland (approximately 6% of the total population) from 1997 to 2005. Patients with a first diagnosis (defined as a first hospitalisation or first recording of the diagnosis in primary or secondary care) of myocardial infarction (MI), angina, and peripheral arterial disease (PAD) were identified. Patients who died within the first 30 days of diagnosis/first hospitalisation were excluded from further analysis. Data on prescribing of evidence based therapies (angiotensin converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARBs), β-blockers, statins and antiplatelet agents [aspirin or clopidogrel]) within 30 days of diagnosis was obtained from primary care database records. Multivariable logistic regression was conducted to examine the association between prescribing of evidence based pharmacotherapies and age, sex, socioeconomic status, comorbidities and year of diagnosis. Results: Between 1997 and 2005, 4305 (83.4%) patients with a first diagnosis of MI, 7210 (98.6%) with angina, and 3385 (95.8%) with PAD had survived to 30 days after their first diagnosis. Increasing age was associated with lower odds of being prescribed evidence based therapies. This association persisted after adjustment for sex, socioeconomic status, year of diagnosis, and comorbidities. In general, older patients ≥ 85 were significantly less commonly prescribed evidence based therapy (EBTs), however they were significantly prescribed nitrates (OR 1.29; 95% CI 1.05-1.59, P<0.01) for angina. Generally men were more likely to be prescribed evidence based therapies than women. After adjustment, prescribing of evidence based therapies was significantly higher in men with a MI for β-blockers (OR 1.18; 95% CI1.04-1.33, P< 0.01), ACEI/ARBs (OR1.26; 95% CI1.05-1.47, P< 0.01) in angina, and statins in men (OR 1.39; 95% CI1.01-1.93, P< 0.04) with PAD and coronary heart disease (CHD). In contrast, men diagnosed with isolated PAD were significantly less commonly prescribed statins than women (OR 0.73; 95% CI0.59-0.91, P< 0.004). Prescribing of evidence based therapies varied negligibly between the most deprived and least deprived patients. These minor differences disappeared after adjustment except for β-blockers which were significantly less likely to be prescribed for patients who had been diagnosed with angina and were residing in quintile 9 compared to the least deprived area (OR 0.76, 95% CI 0.58-1.00, p= 0.05). Prescribing of evidence based therapies increased between 1997 and 2005, particularly for ACEIs/ARBs, β-blockers, statins and antiplatelet agents. Generally the presence of comorbidities was associated with lower odds of being prescribed evidence based therapies. When comparing prescribing rates between the different diagnoses, patients with a first MI were more likely to be prescribed ACEI/ARBs, β-blockers, statins, aspirin and clopidogrel compared to angina. All evidence based therapies were less likely to be prescribed for those with PAD compared to patients with a MI or angina. Conclusion: In conclusion, I have shown that prescribing of evidence based therapies has improved over time, though rates remain low. Prescribing evidence based therapies is inequitable, though not always significant, for age, sex, and socioeconomic status. Concomitant disease decreased the odds of being prescribed evidence based therapies. More studies are needed to identify the reasons for the prescribing inequalities and low rates observed. Further studies are needed to examine the existence of other inequalities in using evidence based therapies such as dosing and to find strategies to improve prescribing rates