Cardiovascular risk thresholds for intensifying primary care encounter frequency for patients with type 2 diabetes mellitus: a target trial emulation

Abstract

Background: Determining optimal timing for intensifying the frequency of physician encounters for type 2 diabetes mellitus (T2DM) requires trade-offs between timely care and clinician burden. We aimed to investigate agespecific cardiovascular disease (CVD) risk thresholds used for intensifying encounter frequency in patients with T2DM in primary care. Methods: Using population-based public electronic health records from the Hospital Authority Clinical Management System in Hong Kong, we used data from patients with a baseline 10-year CVD risk of lower than 20% and a regular follow-up interval of 4–6 months at public primary care clinics. We compared different CVD risk thresholds (> 20% v. 30%) at which to shorten follow-up intervals to 3 months or less. We investigated agespecific effects by categorizing patients into 4 age groups (< 50, 50–59, 60–69, and ≥ 70 yr). In the causal framework of the target trial emulation, we used a dynamic marginal structural model to estimate absolute risk differences for 5-year incidence of CVD, under the assumption of no unmeasured confounding. Results: We identified 44 813 patients. Compared with the risk threshold of 20%, adopting the threshold of 30% did not increase risk of overall CVD in patients younger than 50 years (absolute risk difference 0.2%, 95% confidence interval [CI] –0.6% to 1.0%) and aged 50–59 years (absolute risk difference 0.7%, 95% CI –0.1% to 1.4%). However, we observed an increased risk in older patients, aged 60–69 years (absolute risk difference 1.5%, 95% CI 0.6% to 2.5%) and 70 years or older (absolute risk difference 2.7%, 95% CI 0.6% to 4.9%). Interpretation: When adopting a less stringent CVD risk threshold of 30% to intensify encounter frequency, we found progressively increasing risks with age for 5-year CVD incidence, and age 60 years appears to be a point where the risk becomes pronounced. Our findings suggest that a less stringent threshold could be considered for patients with T2DM who are younger than 60 years but not for those older than 60 years.