National dispensing of evidence-based treatment for New Zealand patients before and after peripheral arterial or percutaneous coronary procedures; undertreatment in plain sight

Abstract Background/Introduction Cardiovascular management guidelines recommend that those undergoing arterial procedures for atherosclerotic disease should be on a long-term antithrombotic agent, statin and blood pressure (BP) lowering (triple therapy) to prevent or delay future ischaemic events or death. Internationally, treatment gaps have been reported for people having peripheral arterial disease (PAD) procedures. Purpose We aimed to investigate national rates of triple therapy dispensing before and after admission for a percutaneous coronary intervention (PCI) compared to a PAD procedure. Methods All people aged 18-84 years admitted for a publicly-funded PCI or PAD procedure in New Zealand between 1 January 2015 and 30 June 2020 were identified. Data were linked to national community dispensing records for antithrombotic agents, statins and BP lowering and the adjusted relative risk (adjRR) of dispensing individual medication classes and triple therapy investigated 6 months prior-procedure and 0-6 months and 7-12 months post-procedure. Analyses were controlled for age, sex, prioritised ethnicity, socioeconomic deprivation index, diabetes and prior cardiovascular disease. Results During the study period, 26,383 people were admitted for a PCI procedure and 10,938 people for PAD. Compared to PCI, those with PAD were more likely to be women, older (median age 69 vs 66 years), of Māori or Pacific ethnicity, living in more deprived communities, more likely to have diabetes (33% vs 24%) and a prior admission for cardiovascular disease (63% vs 52%). Triple therapy in the 6 months prior to procedure was 48% for PAD compared to 37% for PCI (adjRR 1.04; 1.03-1.05); however, in the 6 months post-discharge, improved for PCI more than PAD (PAD 58% vs PCI 91%, [adjRR 0.82; 0.81-0,83]) with decreased dispensing in both cohorts by 7-12 months post procedure (PAD 55% vs PCI 83%, [adjRR 0.84; 0.83-0,84]). Conclusions Patients undergoing atherosclerotic arterial procedures are at high risk of future fatal and nonfatal cardiovascular events. Less than half the patients who were admitted for a PCI or PAD procedure had been dispensed triple therapy in the 6 months prior to admission. Post procedure, 91% of PCI patients were on triple therapy but this substantial increase did not occur for PAD patients. The risk management gap for those who have peripheral arterial compared to coronary procedures indicates clear clinical and system-related deficiencies and a national quality improvement approach is required to address these issues. Figure 1. Adjusted relative risk of being dispensed preventive medications for patients who had a PAD procedure, compared to patients who had a PCI procedure [after adjusting for age, sex, ethnicity, NZDep, history of CHD (including prior PCI and CABG), stroke/TIA, haemorrhagic stroke, heart failure, PVD, and diabetes]