The effect of waiting times on health outcomes for coronary bypass and angioplasty

Long waiting times are a major health policy issue across many OECD countries, and have been exacerbated by the COVID-19 pandemic. For urgent care, such as for cardiovascular conditions, a major concern for patients is that health may deteriorate while waiting and waiting times could affect health outcomes. This study investigates the effect of waiting times on health outcomes and resource use for two common procedures for patients with coronary heart disease: coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). In addition to controlling for a range of patient characteristics and hospital characteristics (through hospital fixed effects), we pursue an instrumental variable approach. For each patient, we instrument the referral-to-treatment waiting time with a measure of provider congestion, which is calculated as the average waiting time of patients admitted to the same hospital and referred to the outpatient services in the 30 days preceding the referral of a given patient. We conduct separate analyses before (2015–2019) and after COVID-19 (up to 2021/22). Our IV results suggest that longer waiting times do not lead to higher mortality, readmission rates or longer hospital length of stay for either CABG or PTCA during the pre-pandemic period. Instead, we find that during the pandemic, when waiting times increased substantially, an increase in waiting time by two months for patients undergoing CABG leads to a 0.5 and 0.8 percentage points increase in 30-day and 1-year mortality respectively, and extends hospital length of stay by 0.2 days. These effects are particularly evident among older, more complex, and more deprived patients. There is no statistically significant relationship between waiting times and outcomes for the PTCA sample in the pandemic period.