Table 3.

Poisson Regression Models Predicting Incident Dementia From Birth Cohort (N = 3,010)

Basic Models	IRR	95% CI for IRR	p
Model 1
Born 1902–1911 (referent)
Born 1912–1921	0.639	0.469–0.870	.005
Born 1922–1931	0.358	0.251–0.511	<.001
Born 1932–1941	0.212	0.111–0.402	<.001
Baseline age, y	1.089	1.070–1.109	<.001
Female sex	0.982	0.761–1.268	.891
Model 2
Born 1902–1911 (referent)
Born 1912–1921	0.655	0.477–0.899	.009
Born 1922–1931	0.387	0.265–0.564	<.001
Born 1932–1941	0.233	0.121–0.449	<.001
Baseline age, y	1.088	1.069–1.108	<.001
Education: less than HS (referent)
HS graduate	0.883	0.653–1.194	.419
College or higher	0.773	0.558–1.072	.122
Female sex	0.990	0.766–1.280	.940

Interaction model	β	95% CI for β	p
Model 3
Born 1902–1911 (referent)
Born 1912–1921	−0.740	−1.286 to −0.194	.008
Born 1922–1931	−1.372	−2.037 to −0.708	<.001
Born 1932–1941	−1.723	−2.763 to −0.683	.001
Baseline age, y	0.085	0.067–0.102	<.001
Education: less than HS (referent)
HS graduate	0.168	−0.379 to 0.714	.548
college or higher	0.126	−0.429 to 0.680	.657
Female sex	−0.076	−0.619 to 0.468	.785
Female and HS graduate	−0.409	−1.066 to 0.248	.223
Female and college or higher	−0.559	−1.251 to 0.133	.114
Female and born 1912–1921	0.429	−0.238 to 1.096	.208
Female and born 1922–1931	0.586	−0.225 to 1.396	.157
Female and born 1932–1941	0.313	−1.000 to 1.625	.641

Note: IRR = incident rate ratio; HS = high school; referents: born 1902–1911, less than HS education, male sex. Estimated coefficients (β) are reported for the interaction model as the exponentiated coefficients (IRR) are non-informative for the interaction terms.