Table 2.
Hazard Ratios and Dementia Incidence Rates Based on Number of Births and Age at Birth: Total sample (N = 7,921)
| Dementia incidence rate (per 1,000 person-years) | Unadjusted HR (95% CI) | Model 1 HR (95% CI) | Model 2 HR (95% CI) | Model 3 HR (95% CI) | Model 4 HR (95% CI) | |
|---|---|---|---|---|---|---|
| Number of births | ||||||
| 0–1 | 7.22 | 1.10 (0.92–1.31) | 0.91 (0.76–1.08) | 0.90 (0.75–1.048) | 0.85 (0.71–1.02) | 0.82 (0.69–0.99) |
| 2 (Ref) | 7.07 | 1 | 1 | 1 | 1 | 1 |
| 3–4 | 6.92 | 0.99 (0.86–1.13) | 0.90 (0.78–1.03) | 0.89 (0.77–1.02) | 0.90 (0.78–1.03) | 0.88 (0.77–1.01) |
| 5+ | 9.06 | 1.41 (1.21–1.64) | 0.95 (0.82–1.12) | 0.85 (0.73–1.00) | 0.86 (0.73–1.01) | 0.85 (0.72–0.99) |
| Model 1: age, race-center Model 2: age, race-center, education Model 3: age, race-center, education, smoking (visit 1), cholesterol (visit 1), BMI category, alcohol use (visit 1), leisure index (visit 1), APOE status (stratified by diabetes, hypertension, race-center; included age modeled as age × time interaction, due to violated proportional hazards assumptions) Model 4: model 3 + stroke | ||||||
| Mother's age when first child borna (years) | ||||||
| <20 years | 8.41 | 1.35 (1.20–1.52) | 1.30 (1.15–1.48) | 1.11 (0.97–1.27) | 1.10 (0.96–1.26) | 1.12 (0.97–1.29) |
| 20–29 years (ref/mode) | 6.81 | 1 | 1 | 1 | 1 | 1 |
| 30 years and older | 8.43 | 1.29 (1.03–1.62) | 1.13 (0.90–1.43) | 1.19 (0.95–1.50) | 1.21 (0.96–1.54) | 1.22 (0.96–1.54) |
|
aIn N = 7,222; For age at birth: Model 1: age, stratified by race-center Model 2: age, education, stratified by race-center Model 3: age, race-center, education, smoking (visit 1), cholesterol (visit 1), BMI category, alcohol use (visit 1), leisure index (visit 1), APOE status (stratified by diabetes, hypertension, race-center; included age modeled as age × time interaction, due to violated proportional hazards assumptions) Model 4: model 3 + stroke | ||||||
Bold values indicate confidence interval does not cross 1.
CI, confidence interval; HR, hazard ratio.