Statistical analysis methods
Measurement data are expressed as
mean and standard deviation (SD); classification and grade data are
expressed as rate and constituent ratio. Chi-square test is used for
classification and grade data; t-test or analysis of variance is used
for measurement data; Pearson correlation and Spearmen rank correlation
(rank data) are used for correlation analysis. For MACEs incidence
during follow-up, we will use multivariate Cox regression models to test
the difference between BVHS groups, adjusting for possible imbalanced
variables at the baseline. We will also test if the intervention effect
is modified by age, gender, cardiovascular risk factors and number of
medications. Discrimination was evaluated by the C statistic.
Calibration was assessed using a calibration plot. A P<0.05 (two-side) is statistically significant. Data inventory
and management using SAS (version 3.5.1, Vienna, Austria); all
statistical analysis is completed by SAS (except for the construction of
multi-level model needs to be combined with professional software
MLwiN2.10).