All analyses were conducted with Stata version 9.2 (Stata/SE 9.2; StataCorp, College Station, TX). All reported P values were 2-tailed, and values ,0.05 were considered statistically significant.
All analyses were conducted with Stataversion 9.2 (Stata/SE 9.2; StataCorp,College Station, TX). All reported P valueswere 2-tailed, and values ,0.05 wereconsidered statistically significant.