Originally, 1696 participants were planned in the study (with 424 participants randomized to each arm). However, only a total of 211 participants completed the randomization procedure as of 26 September 2007. Thus, sanofi-aventis, in accordance with the Steering Committee, decided to stop the participant recruitment as of 26 September 2007. Participants who had already signed their Informed Consent (IC) before September 26, 2007 were allowed to enter the randomization if they met eligibility criteria. The final revised number of planned participants to be randomly assigned to the 4 treatment arms was 250, and 228 participants were actually randomized.