Table 2.

Crude aMCI Incidence Rates by Age at Diagnosis and Year of Birth Category

	Year of Birth Category (N)
Age (y)	1899–1920 (372)	1921–1925 (241)	1926–1930 (315)	1931–1946 (305)	Total (1,233)
70–74	# aMCI Cases		0	12	7	19
	Person-years (PY)		23.69	336.12	380.06	739.86
	Rate/100 PY		0	3.57	1.84	2.57
75–79	# aMCI Cases	0	9	17	18	44
	Person-years (PY)	142.32	323.07	592.32	556.14	1,613.84
	Rate/100 PY	0	2.79	2.87	3.24	2.73
80–84	# aMCI Cases	21	19	13	8	61
	Person-years (PY)	551.97	413.81	536.81	194.12	1,696.71
	Rate/100 PY	3.81	4.59	2.42	4.12	3.60
85–89	# aMCI Cases	36	21	12	0	69
	Person-years (PY)	512.36	316.23	156.39	1.89	986.86
	Rate/100 PY	7.03	6.64	7.67	0	7.00
90–94	# aMCI Cases	17	8	1	——	26
	Person-years (PY)	195.41	57.95	0.94		254.30
	Rate/100 PY	8.70	13.81	106.80		10.22
≥95	# aMCI Cases	5	——	——	——	5
	Person-years (PY)	29.37				29.37
	Rate/100 PY	17.02				17.02
Total	# aMCI Cases	79	57	55	33	224
	Person-years (PY)	1,431.43	1,134.74	1,622.58	1,132.21	5,320.96
	Rate/100 PY	5.52	5.02	3.39	2.91	4.21