Statistical Analyses
Data analyses were performed using the Statistical Package for Social Sciences program version 24.0 (IBM SPSS Statistics for Windows; IBM Corp, Armonk, NY). Descriptive statistics in the form of frequencies and percentages were reported for categorical variables and mean ± standard deviation (SD) for continuous variables. The chi-square test was used to compare categorical variables between the two groups (atorvastatin 80mg users vs. atorvastatin 40mg users), and Student’s t-test was used to compare continuous variables between the two groups.
Cox proportional hazard regression analysis was used to assess the association between atorvastatin doses and time-to-primary composite outcome and secondary effectiveness outcomes at 1 month and 12 months following discharge. The 1-month and 12-month Cox proportional hazard models were adjusted for clinically relevant variables. The results were presented as unadjusted hazard ratio and adjusted hazard ratio (aHR) with 95% confidence intervals (CIs). A P-value of <0.05 was used to indicate statistical significance. Furthermore, multivariate logistic regression was used to determine the predictors of prescribing atorvastatin 80mg among ACS patients. Sixteen clinically relevant variables were included in the logistic regression model, using the backward stepwise likelihood ratio with the probability of entry of 0.05 and removal of 0.10 at each step. The results are presented as adjusted odds ratio (aOR) with corresponding 95% CI. A P-value of <0.05 was used for statistical significance.