Risk of cardiovascular events according to the tricyclic antidepressant dosage in patients with chronic pain: a retrospective cohort study

Abstract

Purpose: We aimed to examine the risk of cardiovascular adverse events by tricyclic antidepressant (TCA) dosage among patients with chronic pain.

Methods: A retrospective cohort study was conducted using a nationwide sample cohort. Among patients aged ≥ 18 years with a chronic pain diagnosis and no history of cardiovascular events, we extracted users and non-users of TCAs through 1:1 propensity score matching. TCA users were categorized into three groups according to the mean defined daily dose (DDD): very low doses (< 0.15 DDD), low doses (0.15-0.34 DDD), and traditional doses (≥ 0.34 DDD). A 6-month follow-up was conducted with an intention-to-treat approach. We examined the hazard ratio of cardiovascular adverse events using Cox proportional hazards analysis.

Results: In total, 16,660 matched patients were followed up (8330 TCA users and 8330 non-users). TCA use did not significantly increase cardiovascular adverse events (hazard ratio [HR] 1.12, 95% confidence interval [CI] 0.94-1.33). Low-dose (0.15-0.34 DDD) TCAs (HR 1.37, 95% CI 1.08-1.74), particularly low-dose (0.15-0.34 DDD) nortriptyline (HR 2.11, 95% CI 1.44-3.08), was associated with an increased risk of cardiovascular adverse events. Administration of TCAs at the traditional dose (≥ 0.34 DDD) increased the risk of ischemic stroke (HR 2.08, 95% CI 1.11-3.88).

Conclusion: Close monitoring of patients on long-term, low-dose use of TCAs should be conducted to avoid an increase in the cumulative dose, which increases the risk of cardiovascular adverse events.

Keywords: Cardiovascular adverse events; Chronic pain; Low dose; Tricyclic antidepressants.