Statin prescribing for prevention of cardiovascular disease amongst people with severe mental illness: Cohort study in UK primary care

Abstract

Background: Severe mental illness (SMI) is associated with excess cardiovascular disease (CVD) morbidity, but little is known on provision of preventative interventions. We investigated statin initiation for primary CVD prevention in individuals with and without SMI.

Methods: We used primary care data from The Health Improvement Network from 2006 to 2015 for UK patients aged 30-99years with no pre-existing CVD conditions and selected individuals with schizophrenia (n=13,252) or bipolar disorder (n=11,994). In addition, we identified samples of individuals without schizophrenia (n=66,060) and bipolar disorder (n=59,765), but with similar age and gender distribution. Missing data on CVD covariates were estimated using multiple imputation. Statin prescribing differences between individuals with and without SMI were investigated using multivariable Poisson regression models.

Results: Initiation of statin prescribing was between 2 and 3 fold higher in people aged 30-59years with SMI than in those without after adjusting for CVD covariates. The rates in those aged 60-74years with SMI were similar or slightly higher relative to those without SMI. The incidence rate ratio (IRR) was 1.15 (95% CI 1.03-1.28) for bipolar disorder and 1.00 (0.91-1.11) for schizophrenia. The rate of statin prescribing was lower (IRR 0.81 (0.66-0.98)) amongst the oldest (aged 75+years) with schizophrenia relative to those without schizophrenia.

Conclusions: Despite higher rates of new statin prescriptions to younger individuals with SMI relative to individuals without SMI, there was evidence of lower rates of statin initiation for older individuals with schizophrenia, and this group may benefit from additional measures to prevent CVD.

Keywords: Bipolar disorder; Cardiovascular disease; Health inequalities; Schizophrenia; Statins.