*2.6. Statistical Analysis*

AMI hospitalization rates were calculated based on the size of the population in every year of the study period, and are reported as the rates per 100,000 population. Direct age and gender adjustments of in-hospital admissions for AMI (per 100,000 population) by type of AMI were performed using the data for the population in 2012.

Descriptive statistics were obtained for the variable investigated. Patients' characteristics are presented as means and standard deviations (SD), for continuous variables, and using absolute and relative frequencies for categorical data.

We examined the two performance indicators by subgroup for gender (men and women), age (<45, 45–64, 65–74, 75–84, >84), and citizenship, for each year between 2007 and 2016. The annual percent changes (APC) and relative confidence intervals (CIs) were calculated to identify trends for all the variables investigated.

Two predictive models were built to estimate the relationships between the performance indicators and socio-demographic factors and, to take the hierarchical structure of the data into account, we performed multilevel logistic regression with random intercepts for hospitals, controlling for potential intra-hospital correlations. Next, to investigate disparities in outcomes by gender, age, and citizenship, we pooled the calendar years into two periods, before (2007–2008) and after (2009–2016) the introduction of the network. All statistical analyses were performed using STATA software, version 12.1 (Stata Corp LP, College Station, TX, USA). All *p*-values reported are two-sided, with a significance threshold of *p* < 0.05.
