RT Journal A1 Derauf D T1 GRoup vs individual well-child care JF Archives of Pediatrics & Adolescent Medicine JO Archives of Pediatrics & Adolescent Medicine YR 1999 FD January 1 VO 153 IS 1 SP 91 OP 92 DO UL http://dx.doi.org/ AB However, this study has serious limitations that may jeopardize the results. The first is the uneven distribution of important maternal characteristics between the intervention groups after the randomization process. The authors acknowledge in the "Results" section that the GWCC mothers were significantly more likely at study outset to be abusing alcohol or other drugs than the individual well-child care (IWCC) mothers. They fail to comment, however, on how this uneven distribution may have influenced the overall results. Indeed, given that the GWCC mothers were roughly 3 times as likely to test positive for alcohol abuse and more than twice as likely to test positive for other substance abuse as the IWCC mothers, it is remarkable that both groups had similar outcomes. Did the authors try to control for this potential bias?