Table 1.

Baseline participant characteristics and follow up time, in all participants and by race

Characteristics	All (N=7908)		AA (N=1229)		Caucasian (N=6679)		P*
	n	%	n	%	n	%
Age at 1st visit (yrs): median (IQR)	74.83 (70.08~80.833)		73.33 (69.25~78.5)		75.17(70.33~81.33)		<0.0001
Follow up (yrs): median (IQR)	4.405 (2.075~7.511)		4.293 (2.075~7.211)		4.441 (2.259~7.603)		0.0503
MMSE at 1st visit: median (IQR)	29 (28~30)		28 (27~30)		29 (28~30)		<0.0001
Sex							<0.0001
Women	5087	64.33	974	79.25	4113	61.58
Men	2821	35.67	255	20.75	2566	38.42
Education (yrs): median, IQR	16 (14~18)		14 (12~17)		16 (14~18)		<0.0001
Education							<0.0001
<=12 yrs	1510	19.16	400	32.57	1110	16.68
>12 yrs	6371	80.84	828	67.43	5543	83.32
APOE ε status							<0.0001
22	45	0.64	11	1.08	34	0.57
32	886	12.65	154	15.07	732	12.24
33	4088	58.37	506	49.51	3582	59.88
34	1669	23.83	284	27.79	1385	23.15
42	178	2.54	44	4.31	134	2.24
44	138	1.97	23	2.25	115	1.92
Baseline BMI							<0.0001
<30	5443	75.04	621	55.25	4822	78.68
>=30	1810	24.96	503	44.75	1307	21.32
Vital status							<0.0001
Alive	6657	84.18	1104	89.83	5553	83.14
Dead	1251	15.82	125	10.17	1126	16.86

^*p values were from two-sided Wilcoxon rank sum test for quantitative characteristics and from Fisher’s exact test for qualitative characteristics between AA and Caucasian.

IQR=Interquartile Range; MMSE=Mini Mental State Examination.