Association between pre-stroke comorbidity and post-stroke prescribing in a Scottish ischaemic stroke survivor population: A national data linkage study

Introduction:
Comorbidities can determine treatment after stroke. Certain medications may not be prescribed after stroke due to the potential for polypharmacy or adverse drug reactions, while some medications or classes may be preferred in specific comorbidities.
Aims:
To analyse the impact of pre-stroke comorbidities on the prescribing of secondary prevention medications.
Methods: A population-based study using routinely collected data within the Scottish Stroke Care Audit, Prescribing Information System, and Scottish Morbidity Record 01. First-ever ischaemic stroke patients between July 2010 and June 2015, who were discharged to home within 90 days of stroke and then survived to six months after stroke were used for analysis. Multivariate logistic regression models were developed to define the associations between pre-stroke comorbities and post-stroke prescribing.
Results:
There were 25 684 ischaemic stroke patients with a mean age of 70.8 (±13.5) years and 12 620 (49.4%) were women. The most common comorbidities were diabetes (19.4%), pulmonary disease (17.8%), atrial fibrillation (17.7%), and myocardial infarction (12.9%). Patients with myocardial infarction or diabetes had higher odds of receiving a prescription for an antiplatelet, antihypertensive and statin after stroke. Atrial fibrillation was associated with lower odds for antiplatelet or statin therapy, but higher odds of antihypertensive therapy. Neither cancer, dementia nor pulmonary disease were associated with the prescribing of secondary prevention medications after stroke. Higher Charlson comorbidity index scores was associated with lower odds of antihypertensive and statin prescribing after stroke.
Conclusions: Pre-stroke comorbidity was found to have a significant impact on the prescribing of secondary prevention medications after stroke in Scotland.