Discontinuation and restarting in patients on statin therapy: a cohort study using a primary care database
Cardiovascular disease (CVD) has a major impact on the lifestyle of affected individuals and is a significant burden for health services. Statins have been shown to decrease CVD risk and are recommended for all patients with a 10 year risk of CVD of 10% or more. The preventive benefit, however, depends on adherence to the therapy, which at the more extreme end includes discontinuation without subsequent restarting. We have undertaken a study to determine the discontinuation and restarting rates of statin users in the UK general population, identifying patient characteristics associated with discontinuation and with restarting.
From 664 UK general practices contributing to Clinical Practice Research Datalink, an open cohort of incident statin users between 2002 and 2013 was identified. These patients were subdivided into a primary prevention group (no prior CVD diagnosis) and a secondary prevention group (with prior CVD diagnosis). Every patient was followed from their first statin prescription until the first 90-day period not covered by a statin prescription, which defined discontinuation. Every patient who discontinued was subsequently followed until the first post-discontinuation statin prescription, which defined restarting. To identify factors associated with these outcomes, Cox proportional hazards model including life-style factors, co-morbidities and other medications was used.
During the study period, of 431,023 patients prescribed statins for primary prevention, 226,401 (53%) remained on statins, 147,305 (34%) discontinued temporarily, and 57,317 (13%) discontinued without subsequent restarting. Of the 139,314 patients in the secondary prevention group, 81,523 (59%) remained on statins, 43,211 (31%) discontinued temporarily, and 14,580 (10%) discontinued without subsequent restarting.In the primary and the secondary prevention groups, patients younger than 50 years, patients older than 78 years, women and patients with chronic liver disease were both more likely to discontinue statins and less likely to restart. In both prevention groups, patients from ethnic minorities, smokers and patients with type 1 diabetes were more likely to discontinue but then more likely to restart. In the primary prevention group only, patients with hypertension and type 2 diabetes were less likely to discontinue statins.
Although large numbers of statin users do discontinue, many of them restart. The factors associated with discontinuation and restarting suggest that for some patient groups previously considered ‘stoppers’, the issue may be more akin to the wider, but in general less risky, problem of poor adherence. Identification of patient groups less likely to restart once discontinued, such as women, may help clinicians to focus more on these groups. The higher likelihoods of both discontinuation and restarting found in many ethnic minority groups is similarly important, and suggests a need for further research based on access to a broader range of detailed social and cultural information in order to identify the reasons and possible solutions.