Table S1.

Complete case analysis: age-standardized percentages of white and black people developing dementia in the UK in 2015 who were diagnosed

Ethnicity	Sex	Age group (years)	Number of people in the UKa	Estimated incidence of dementiab	Estimated number of dementia cases in the UKc	Sex- and ethnicity-specific number of people in THINd	Estimated number of dementia diagnoses in THINe	Number of observed dementia diagnoses in THINf	Age-standardized percentage of dementia diagnosesg
White	Male	65–69	1,669,359	0.005	8,347	83,705	419	113	30
		70–74	1,223,303	0.009	10,643	65,671	571	178	32
		75–79	943,425	0.017	15,755	50,698	847	261	31
		80–84	654,607	0.025	16,234	38,446	953	352	34
		85–89	358,444	0.038	13,621	27,165	1,032	255	18
	Sum		4,849,138			265,685			29
	Female	65–69	1,768,946	0.005	8,137	86,934	400	115	31
		70–74	1,348,258	0.006	8,629	68,781	440	185	43
		75–79	1,113,079	0.016	17,921	56,380	908	334	38
		80–84	872,250	0.040	34,541	46,983	1,861	481	25
		85–89	589,318	0.055	32,589	39,893	2,206	495	17
	Sum		5,691,851			298,971			31
Black (incidence ratio 1.63)	Male	65–69	21,021	0.008	171	642	5	1	25
		70–74	21,177	0.014	299	574	8	4	73
		75–79	14,549	0.027	395	735	20	2	8
		80–84	7,223	0.040	291	435	18	3	11
		85–89	2,226	0.062	137	281	17	4	7
	Sum		66,197			2,667			25
	Female	65–69	22,275	0.007	167	1,004	8	4	57
		70–74	23,340	0.010	243	935	10	2	25
		75–79	17,165	0.026	449	894	23	9	36
		80–84	9,625	0.064	619	566	36	4	9
		85–89	3,661	0.090	329	261	23	7	20
	Sum		76,066			3,660			29

Notes: Incidence in the white ethnic group obtained from Matthews et al;¹ incidence in black ethnic group obtained by multiplying that in the white ethnic group by 1.63;² results obtained following complete case analysis excluding individuals with missing data in The Health Improvement Network (THIN) sample. Cell values displayed as frequency in columns a,c–f; proportion in column b; and percentage in column g. Cell calculations: c=a×b, e=d×b, g=(f/e)×(a/∑_a)/(d/∑_d)×100.