DIFFERENCE IN PRESCRIBED MEDICATIONS AND 5-YEAR MORTALITY BETWEEN FIRST NATIONS AND NON-FIRST NATIONS ANGIOGRAPHY PATIENTS

Abstract

Improved development and uptake of pharmacological therapies for the management of cardiovascular disease symptoms has contributed to lower mortality rates. This study sought to explore guideline-recommended prescribing of medications among First Nations (FN) and non-FN patients following angiography and whether any differences in rates of filling prescriptions over the following year (proxy for medication use) is associated with CVD mortality disparities between populations. All index angiography patients (≥18 years) during 2000/0 -2008/09 in Manitoba were identified using health administrative data. Patients were separated by whether or not their angiography occurred during an AMI hospitalization (AMI and non-AMI groups). Medications dispensations were observed for beta-blockers, ACE-inhibitors, statins, and clopidogrel within three-months of angiography. Medication possession ratios (MPR) for each were calculated over a one-year period starting from the date of the first dispensation and patients were assigned to 1 of 4 categories based on their MPR: 1) not dispensed; 2) low MPR (<40% MPR); 3) intermediate MPR (≥40% to ≤79% MPR); 4) high MPR (≥80% MPR). Cox proportional models examined differences in all-cause and cardiovascular mortality using a model that controlled for socio-demographic variables and comorbidities, and a second model that also included the MPR categories. In the AMI group, the proportion of non- FN patients with high MPRs was greater for each medication class except for clopidogrel compared to FN patients. In the non-AMI group, the proportion of FN patients with high MPRs was greater for clopidogrel and ACE-inhibitors compared to the non-FN patients. In the first adjusted model, FN patients had an increased cardiovascular mortality in both groups (HR AMI group = 1.57; 95%CI: 1.05-2.35; HR non-AMI group = 1.50; 95%CI: 1.17-1.94; Table 1). Adding the MPR variable attenuated the relationship in both groups and the hazard was only significantly higher for FN patients in the non-AMI group (HR = 1.40; 95%CI: 1.08-1.80). Similarly, with the all-cause mortality model that included MPR variable, only FN patients in the non-AMI group were significantly higher (HR model 1 = 1.52; 95%CI: 1.28-1.79; HR model 2 = 1.45; 95%CI; 1.23-1.71). There were differences in the patterns the use of prescribed guideline-recommended medications between FN and non-FN patients. FN patients were less likely to have high MPRs for some of the medication classes, but not all. FN patients had higher cardiovascular mortality than non-FN patients, which was consistent with differences in medication utilization only in the AMI group.