2.6. Statistical analysis

Differences in mean values among the normal BP, pre-HT, and HT groups were tested using analysis of variance. Tukey's honestly significant difference test was used for intergroup differences. Differences in percentages among these groups were estimated using a chi-square test. The Kaplan-Meier method was applied for each BP group, and comparisons were made using the log-rank test. P values were calculated using the log-rank test. We used the multivariable adjusted Cox hazard model as a tool to assess the risk of CVD. Statistical analysis was performed using SPSS ver. 16.0 (SPSS Inc., Chicago, IL, USA). P values < 0.05 were considered to indicate statistical significance.