There was no significant shift in the distribution of 90-day disability outcomes on the global modified Rankin scale between patients in the magnesium group and those in the placebo group ( P = 0.28 by the Cochran-Mantel-Haenszel test ) ; mean scores at 90 days did not differ between the magnesium group and the placebo group ( 2.7 in each group , P = 1.00 ) .