Afro-Americans have a poorer response to citalopram compared to Caucasians.
There were overall significant differences (unadjusted data) between Caucasian (self-identied as US 'white) and Afro-Americans (self-identied as US 'blacks') participants with nonpsychotic depressive disorder who achieved remission on the clinician-rated HRSD17 (Caucasian remission rate = 30.1%; Afro-American remission rate = 18.6%; p<0.0001) and the participant-rated QIDS-SR16 (Caucasian remission rate = 36.1%; Afro-American remission rate = 22.2%; p<0.0001).
After adjustment (see note 1) the differences in remission between Caucasians and Afro-Americans disappeared in the HRSD17 but remained in the QIDS-SR16 (odds ratio Caucasian = 1; odds Afro-American = 0.698; p=0.0183).

note 1:
Adjusted for:
regional center, gender, education, employment, income, medical insurance, marital status, illness onset age and duration, n episodes, family history of mood disorder and substance abuse, current episode duration, HRSD17 or QIDS-SR16, anxious and melancholic subtype features, SF12, Q-LES-Q, WSAS, specialty care setting, CIRS ratings sum, and n psychiatric disorders.

(N=2348; Caucasian = 1853; Afro-American = 495), Lesser et al., 2007.