Multimorbidity and cardiovascular prevention in primary care: a cohort study in New Zealand

Multimorbidity adds complexity to cardiovascular disease (CVD) prevention. Clinical guidelines in Aotearoa New Zealand recommend combined blood pressure- and lipid-lowering therapy ('dual therapy') for most people at high (≥15%) 5-year CVD risk; recommend shared decision making for those at intermediate risk (5-14%); and do not generally recommend dual therapy for those at low risk (<5%).

To examine the association between multimorbidity and dispensing of dual therapy across CVD risk groups.

Cohort study of patients enrolled in a primary health organisation serving the Auckland region of northern New Zealand.

The study included 430 286 adults aged 30-79 years without prior CVD who were enrolled in ProCare in 2014. Multivariable Poisson regression was used to estimate relative risks (RRs) for receiving dual therapy within each CVD risk group. Two-year maintenance of dual therapy was compared by multimorbidity status.

Baseline dual therapy dispensing was 2.5%, 31%, and 40% in the low-, intermediate-, and high-risk groups, respectively. Multimorbidity was associated with a greater likelihood of receiving dual therapy across all risk groups (low risk: RR 2.90, 95% confidence interval (CI) = 2.77 to 3.03; intermediate risk: RR 1.35, 95% CI = 1.32 to 1.38; high risk: RR 1.15, 95% CI = 1.10 to 1.22). Among participants receiving dual therapy at baseline, maintenance was higher among those with multimorbidity in the low-risk group (88% versus 84%) and intermediate-risk group (90% versus 86%) (both P<0.001). In the high-risk group, maintenance was similarly high irrespective of multimorbidity (89% versus 88%; P = 0.412).

Patients with multimorbidity were more likely to receive and maintain guideline-recommended CVD preventive therapy than those without multimorbidity. However, despite increasing use of dual therapy with increasing CVD risk, substantial evidence-practice gaps remained among patients at high CVD risk.