Characteristics of patients in derivation sample, validation sample, and cross-validation sample.

Abbreviations: SSRI, selective serotonin reuptake inhibitor; HAM-D, Hamilton depression rating score.aFisher's exact test.bMann-Whitney test.cCorrected by Bonferroni's correction for multiple testing.+Comparison between derivation sample and validation sample.++Comparison between derivation sample and cross-validation sample.Characteristics of patients in derivation sample, validation sample, and cross-validation sample.