Differential impact of ambulatory visits to specialist physicians on major cardiovascular events among incident cases of diabetes with or without known coronary heart disease: a cohort study
Authors: O'connor S , Blais C , Sylvain-Morneau J , Diop A , Mesidor M , Leclerc J , Poirier P 
Published: June 2024

Abstract

Background
Following a diagnosis of diabetes, specialist physicians may be solicited regarding the prevention of major cardiovascular events (MACE) (stroke, myocardial infarction, cardiovascular death). Patients with established coronary heart disease (CHD) are more susceptible to MACE and may require distinct attention. However, trajectories of visits to specialists are heterogenous and their efficacy preventing MACE remains unexplored.

Purpose
To assess whether trajectories of ambulatory visits to specialists are associated with MACE among new cases of diabetes, considering the presence or absence of CHD.

Methods
Using an integrated surveillance system of linked administrative databases dating back to 1996, we identified new diabetes cases aged ≥20 years during fiscal year 2013, with no history of MACE. Trajectory period: Individual trajectories based on the presence/absence of ≥1 ambulatory visit to a specialist (cardiologist/internist/endocrinologist) were compiled from diagnosis across consecutive 3-month periods, up to 2 years. Patients with no specialist visit constituted a "primary care" group, while others were grouped using latent class trajectory analysis. Patients experiencing a MACE during this period were excluded. Explanatory period: Stratifying by the presence or absence of CHD at the end of the trajectory period, we compared MACE risk between groups using a Cox proportional model, from year 2 post-diagnosis up to 12-31-2019, adjusted with inverse probability weighting and presented as adjusted hazard ratio (aHR) with 95% confidence intervals (CI).

Results
Among the 29,949 patients, we identified 4 trajectory groups (Figure 1). During the trajectory period, the proportion of patients who consulted ≥1 specialist was 64% with known CHD, compared to 35% without CHD. Among patients who met ≥1 specialist, those with CHD were more likely to have consulted a cardiologist (74%) than those without CHD (37%), while they were less likely to have met with an internist (37 vs 50%) or an endocrinologist (11 vs 31%). During the explanatory period, 796 MACE occurred among the 4,783 patients with CHD. Patients who had "early visits only" had a lower risk of MACE, while no difference was observed with "regular/frequent" and "regular/sparce" visits compared with the "primary care" group (Table 1). A total of 1,440 MACE occurred among the 25,166 patients without CHD. Patients with "regular/frequent" visits had no difference in the risk of MACE compared with the "primary care" group, while an increased risk of MACE was observed among those with "early visits only" and "regular/sparce visits".

Conclusions
While confounding by indication may persist, these results highlight the potential role of specialists in averting MACE in the context of CHD. However, the divergent risks of MACE according to the absence of CHD, visit frequency, and timing, advocate for improvement in the preventive role of specialists post-diabetes diagnosis.