In this protocol article, entitled The Impact of Treatment Adherence for Patients With Diabetes and Hypertension on Cardiovascular Disease Risk: Protocol for a Retrospective Cohort Study, 2008-2018, authors Min Su et al., including France Légaré, explain their study to evaluate the impact of treatment adherence on acute severe cardiovascular disease (CVD) events and intermediate clinical outcomes in Canadian primary care settings. Their findings will help to identify adherence challenges and in developing intervention strategies to promote treatment adherence for patients with multi-morbidities.