Research Article: Under-prescribing of Prevention Drugs and Primary Prevention of Stroke and Transient Ischaemic Attack in UK General Practice: A Retrospective Analysis

Date Published: November 15, 2016

Publisher: Public Library of Science

Author(s): Grace M. Turner, Melanie Calvert, Max G. Feltham, Ronan Ryan, David Fitzmaurice, K. K. Cheng, Tom Marshall, Kazem Rahimi

Abstract: BackgroundStroke is a leading cause of death and disability; worldwide it is estimated that 16.9 million people have a first stroke each year. Lipid-lowering, anticoagulant, and antihypertensive drugs can prevent strokes, but may be underused.Methods and FindingsWe analysed anonymised electronic primary care records from a United Kingdom (UK) primary care database that covers approximately 6% of the UK population. Patients with first-ever stroke/transient ischaemic attack (TIA), ≥18 y, with diagnosis between 1 January 2009 and 31 December 2013, were included. Drugs were considered under-prescribed when lipid-lowering, anticoagulant, or antihypertensive drugs were clinically indicated but were not prescribed prior to the time of stroke or TIA. The proportions of strokes or TIAs with prevention drugs under-prescribed, when clinically indicated, were calculated.In all, 29,043 stroke/TIA patients met the inclusion criteria; 17,680 had ≥1 prevention drug clinically indicated: 16,028 had lipid-lowering drugs indicated, 3,194 anticoagulant drugs, and 7,008 antihypertensive drugs. At least one prevention drug was not prescribed when clinically indicated in 54% (9,579/17,680) of stroke/TIA patients: 49% (7,836/16,028) were not prescribed lipid-lowering drugs, 52% (1,647/3,194) were not prescribed anticoagulant drugs, and 25% (1,740/7,008) were not prescribed antihypertensive drugs.The limitations of our study are that our definition of under-prescribing of drugs for stroke/TIA prevention did not address patients’ adherence to medication or medication targets, such as blood pressure levels.ConclusionsIn our study, over half of people eligible for lipid-lowering, anticoagulant, or antihypertensive drugs were not prescribed them prior to first stroke/TIA. We estimate that approximately 12,000 first strokes could potentially be prevented annually in the UK through optimal prescribing of these drugs. Improving prescription of lipid-lowering, anticoagulant, and antihypertensive drugs is important to reduce the incidence and burden of stroke and TIA.

Partial Text: Stroke is a leading cause of death and disability worldwide, with an estimated annual incidence of 16.9 million first strokes and 6 million stroke-related deaths [1]. Although the age-standardised incidence rates have decreased over the past two decades, the absolute numbers of strokes and stroke-related deaths and disability cases have increased due to the ageing population [1]. Furthermore, transient ischaemic attack (TIA) is an important risk factor for stroke that also has a high prevalence worldwide [2].

The full protocol for this study has been published [20]; methods are summarised in brief below. Analysis of The Health Improvement Network (THIN) database has ethical approval from the National Health Service South-East Multicentre Research Ethics Committee, subject to independent scientific review [21]. This study had approval by a scientific review committee that is administered by IMS Health Real-World Evidence Solutions (reference: 13–023).

During the study period, 29,043 people with stroke or TIA met the inclusion criteria (16,245 stroke only, 10,446 TIA only, and 2,352 stroke with previous TIA). The median age was 74 y (interquartile range 64, 82), and 51% were female. At the time of their stroke or TIA, 17,680 patients (61%) had a clinical indication for one or more stroke prevention drugs: 9,953 had one prevention drug indicated, 6,904 had two indicated, and 823 had three indicated. In all, 16,028 (55%) patients had a clinical indication for lipid-lowering drugs, 3,194 (11%), for anticoagulant drugs, and 7,008 (24%), for antihypertensive drugs. Descriptive characteristics of patients with clinical indications for each prevention drug are presented in Table 2. A clinical code indicating that prevention drugs were declined or contraindicated, that a patient had white coat hypertension (for hypertensive patients), or that there was an adverse reaction was recorded in only 5% (869/16,028) of patients with a clinical indication for lipid-lowering drugs, 7% (244/3,194), for anticoagulant drugs, and 0.7% (47/7,008), for antihypertensive drugs (S2 Fig).

In this study carried out in UK primary care, six out of ten patients who had a first stroke or TIA were eligible for at least one prevention drug at the time of their stroke or TIA; over half of these were not prescribed prevention drugs that were clinically indicated. In effect, one-third of all strokes or TIAs occurred in patients who had prevention drugs clinically indicated but were not prescribed them. This included half of patients who had lipid-lowering or anticoagulant drugs clinically indicated and a quarter of patients who had antihypertensive drugs clinically indicated. The under-prescribing of anticoagulants decreased between 2009 and 2013, but there was no change for lipid-lowering and antihypertensive drugs. Over half of the patients not prescribed antihypertensive drugs when clinically indicated had previously been prescribed these drugs, but their prescriptions had stopped, compared to only 14% for anticoagulant drugs and 30% for lipid-lowering drugs. Our findings indicate underuse of lipid-lowering, anticoagulant, and antihypertensive drugs in UK primary care in patients for whom these drugs are clinically indicated for prevention of stroke or TIA.



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