The Effects of Coronary Intervention Strategies in the Management of Frail Elderly Patients with Non-ST-Elevation Acute Coronary Syndrome: A Retrospective Cohort Causal Study

Introduction As the population ages, frailty is expected to become a more common complicating feature in the management of Non-ST-Elevation ACS (NSTEACS). Understanding how frail elderly patients respond to coronary intervention is therefore of significant public health importance. We conducted a retrospective cohort study with robust bias-limiting statistical methods to estimate the causal effects of a routine invasive strategy in frail elderly NSTEACS patients. Methods and Results A cohort of frail elderly NSTEACS patients was extracted from three of NSW’s administrative health databases. We used propensity score matching to pair 583 treated and control patients, creating treatment groups that were balanced across many confounders. Regularised conditional logistic regression models and Cox models were used to adjust for residual frailty risk in estimating the causal effects of a routine invasive strategy on several outcomes. A routine invasive strategy significantly decreased the odds of one-year all-cause death (OR = 0.46), one year MACE (OR = 0.59) and in-hospital death (OR = 0.23) but significantly increased the odds of in-hospital major bleeding (OR = 1.49). Treatment decreased the long-term hazard rates of all-cause death (HR = 0.60) and MACE (HR = 0.62). The Hospital Frailty Risk Score was significantly associated with the odds of one-year all-cause death (OR = 1.02) and the hazard rates of all-cause death and MACE (both HR = 1.02). No differential treatment effects between subgroups of frailty risk were observed. Conclusion While frailty risk was associated with increased risk of all-cause death and MACE, a routine invasive strategy decreased the risk of one-year and long-term all-cause death in frail elderly NSTEACS patients, including those at very high frailty risk. Frailty risk alone should not preclude an elderly NSTEACS patient from being treated invasively, but methods to minimise and manage the higher odds of in-hospital major bleeding are essential.