Thirty-year trends in dementia: a nationwide population study of Swedish inpatient records

Figures & data

Figure 1 (A) Composition of the sample in every follow-up year by 5-year age groups. (B) Composition of the sample in every follow-up year by the educational level.

Figure 2 Sex-specific incidence rates of dementia in inpatient register per 10,000 for every year of follow-up period.

Table 1 Sex-stratified crude incidence rates per 10,000 by age group or educational level during the entire follow-up period (1987–2016)

Sex	Strata	Level	Person- years	% of person- years	Crude incidence rates per 10,000	Dementia diagnosis (n)a
Men	5-year age group	65–69	6,713,612	32.72	8.45	5,672
		70–74	5,595,654	27.27	24.13	13,501
		75–79	4,198,190	20.46	61.52	25,828
		80–84	2,486,846	12.12	124.6	30,985
		85–89	1,138,707	5.55	212.95	24,249
		90–94	335,648	1.64	278.06	9,333
		95+	47,905	0.23	269.07	1,289
	Education	Missing	498,540	2.43	48.82	2,434
		Elementary	10,415,722	50.77	60.42	62,932
		High school	6,500,583	31.68	49.85	32,405
		University	3,101,717	15.12	42.19	13,086
	Total		20,516,562	100	54.03	110,857
Women	5-year age group	65–69	7,125,320	28.28	7.28	5,186
		70–74	6,350,673	25.2	21.6	13,717
		75–79	5,290,058	20.99	57.52	30,429
		80–84	3,585,195	14.23	122.85	44,043
		85–89	1,968,272	7.81	211.48	41,625
		90–94	735,641	2.92	280.5	20,635
		95+	144,678	0.57	271.02	3,921
	Education	Missing	680,397	2.7	61.92	4,213
		Elementary	14,224,533	56.45	72.38	102,963
		High school	7,162,480	28.42	55.58	39,809
		University	3,132,427	12.43	40.13	12,571
	Total		25,199,837	100	63.32	159,556

Notes:

a First diagnosis of dementia in hospital inpatient records (ie, in the Swedish National Patient Register) during the study period.

Figure 3 (A) Age-stratified incidence rates (per 10,000) of first diagnosis of dementia in hospital inpatient records for every year of follow-up in men. (B) Age-stratified incidence rates (per 10,000) of first diagnosis of dementia in hospital inpatient records for every year of follow-up in women.

Table 2 Results from stratified discrete time logistics models with a complementary log-log link function

Age strata (years)	Calendar years	Model 1 – crude		Model 2a		Model 3b
		HR	95% CI	HR	95% CI	HR	95% CI
		Period I – before 2011
65–69	1987–2016	0.995	0.992–0.998	1.008	1.001–1.015	1.001	0.994–1.009
70–74	1987–2016	0.998	0.996–0.999	1.014	1.010–1.019	1.009	1.004–1.014
75–79	1990–2016	1.006	1.005–1.008	1.023	1.020–1.026	1.021	1.018–1.024
80–84	1995–2016	1.020	1.018–1.022	1.033	1.031–1.036	1.033	1.030–1.035
85–89	2000–2016	1.045	1.042–1.047	1.042	1.039–1.045	1.043	1.040–1.046
90–94	2005–2016	1.057	1.051–1.064	1.043	1.032–1.053	1.047	1.035–1.060
95+	2010–2016	1.071	1.032–1.113	1.095	1.052–1.140	1.094	1.050–1.139
		Period II – after 2011
65–69	1987–2016	0.979	0.956–1.002	0.996	0.963–1.031	0.986	0.953–1.020
70–74	1987–2016	0.937	0.923–0.952	0.945	0.924–0.966	0.941	0.920–0.962
75–79	1990–2016	0.962	0.952–0.972	0.955	0.940–0.970	0.953	0.938–0.968
80–84	1995–2016	0.967	0.959–0.974	0.960	0.949–0.971	0.960	0.949–0.972
85–89	2000–2016	0.974	0.967–0.981	0.963	0.953–0.973	0.964	0.954–0.974
90–94	2005–2016	0.999	0.990–1.009	0.984	0.972–0.997	0.985	0.972–0.998
95+	2010–2016	0.984	0.965–1.003	0.983	0.958–1.009	0.982	0.957–1.008

Notes: The models estimate hazard ratio (HR) that a person surviving to given age strata would receive a hospital diagnosis of dementia, per calendar year. The results were post hoc stratified by two periods to quantify the change in trends observed in graphs.

a Adjusted for age (continuous within each age group strata); sex; the proportion of all-cause hospitalizations in each calendar year per age group, sex, and educational level; International Classification of Diseases (ICD) period; and pre- and post-Elderly Reform Act (Ädelreformen), if appropriate.

b Adjusted for all variables in Model 2 and for the educational level.

Figure 4 Age- and education-stratified rates (per 10,000) of first diagnosis of dementia in hospital inpatient records for every year of follow-up.

Table 3 Results from discrete time logistics models with a complementary log-log link function stratified by age groups

Variables in main models	Strata	65–69		70–74		75–79		80–84		85–89		90–94		95+
		HR	P-value	HR	P-value	HR	P-value	HR	P-value	HR	P-value	HR	P-value	HR	P-value
Calendar year		0.996	<0.001	0.997	<0.001	1.003	<0.001	1.018	<0.0001	1.026	<0.0001	1.024	<0.0001	0.988	<0.1
Age (continuous)		1.232	<0.001	1.237	<0.001	1.193	<0.001	1.142	<0.0001	1.077	<0.0001	1.015	<0.001	0.945	<0.0001
Sex	Women	0.852	<0.001	0.880	<0.001	0.917	<0.001	0.972	<0.002	0.990	<0.23	1.012	<0.4	1.018	<0.6
Education	Missing	1.708	<0.001	1.417	<0.001	1.217	<0.001	1.141	<0.0001	1.082	<0.01	0.990	<0.8	0.780	<0.04
	Elementary	1.550	<0.001	1.390	<0.001	1.246	<0.001	1.148	<0.0001	1.097	<0.0001	1.026	<0.2	0.942	<0.3
	High School	1.358	<0.001	1.276	<0.001	1.169	<0.001	1.113	<0.0001	1.091	<0.0001	1.033	<0.2	0.982	<0.8
Interaction models
Calendar year×age			<0.5		<0.5		<0.03		<0.001		<0.002		N/Aa		N/A
Calendar year×sex			<0.2		<0.05		<0.01		<0.01		<0.2		N/A		N/A
Calendar year×education			<0.001		<0.001		<0.01		<0.01		<0.001		N/A		N/A

Notes: The main models estimate a hazard ratio (HR) that a person surviving to given age strata would receive a hospital diagnosis of dementia. If there were significant main effects, up to three interaction models were estimated for every age group strata. For simplicity, only P-values for interactions (from –2 log likelihood-ratio test) are reported. Interaction models estimates and CI estimates are available on request.

a Nonconvergence issue with the models due to small numbers of observations per year.

Figure 5 (A) Age-stratified cumulative incidence (%) of first diagnosis of dementia in hospital inpatient records, adjusted for the competing risk of death, for every year of follow-up in men. (B) Age-stratified cumulative incidence (%) of first diagnosis of dementia in hospital inpatient records, adjusted for the competing risk of death, for every year of follow-up in women.