Table 2.

Demographics for 6,192 patients

Age, years	N total, % female	Aβ42 mean, pg/mL (SD)	Aβ40 mean, pg/mL (SD)	Aβ42/40 mean (SD)	Aβ42/40 <0.160, N, % (indeterminant/high risk of PET positivity)	AP42/40 ≥0.170, N, % (likely PET negative)
<40	83, 65%	38.7 (8.3)	207.3 (43.5)	0.188 (0.021)	3, 4%	69, 83%,
40 to 49	162, 62%	38.2 (8.6)	210.4 (42.4)	0.182 (0.023)	20, 12%,	116, 72%,
50 to 59	582, 63%	40.5 (10.6)	228.7 (57.2)	0.178 (0.024)	138, 24%,	369, 63%,
60 to 69	1,370, 58%	40.6 (10.5)	241.7 (58.5)	0.169 (0.023)	497, 36%	631, 46%,
70 to 79	2,451, 57%	42.9 (11.9)	264.7 (71.0)	0.163 (0.022)	1,157, 47%	863, 35%,
80 to 89	1,417, 54%	45.5 (12.5)	284.9 (77.8)	0.161 (0.021)	713, 50%	436, 31%,
≥ 90	127, 60%	48.1 (10.7)	304.5 (74.0)	0.159 (0.019)	68, 54%,	32, 25%,
All	6,192, 57%	42.7 (11.7)	259.4 (71.3)	0.166 (0.023)	2,596, 42%,	2,516, 41%,