Table 3.
Unadjusted and Adjusted Discrete-Time Proportional Hazards Models for Lifestyle Engagement Classes Predicting Time-to-Dementia Diagnosis
| Model 3 (stratified by MCI) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Model 1 (unadjusted) | Model 2 (adjusted) | Non-MCI | MCI | |||||||||
| HR | 95% CI | p value | HR | 95% CI | p value | HR | 95% CI | p value | HR | 95% CI | p value | |
| Lifestyle engagement group (ref.: Class 4: Least Active) |
||||||||||||
| Class 1: Variety | 0.601 | 0.47, 0.77 | <.001*** | 0.645 | 0.49, 0.84 | .001** | 0.669 | 0.48, 0.93 | .017* | 0.962 | 0.62, 1.49 | .862 |
| Class 2: Intellectual | 0.545 | 0.41, 0.73 | <.001*** | 0.618 | 0.46, 0.83 | .001** | 0.645 | 0.45, 0.93 | .018* | 1.029 | 0.61, 1.73 | .914 |
| Class 3: Social | 0.799 | 0.65, 0.98 | .033* | 0.808 | 0.66, 1.00 | .046* | 0.780 | 0.59, 1.03 | .075 | 1.219 | 0.87, 1.70 | .248 |
| Age | 1.214 | 1.15, 1.29 | <.001*** | 1.205 | 1.12, 1.29 | <.001*** | 1.173 | 1.06, 1.30 | .002** | |||
| >80 | 0.924 | 0.83, 1.03 | .158 | 0.922 | 0.80, 1.06 | .259 | 0.892 | 0.74, 1.07 | .224 | |||
| >85 | 0.848 | 0.70, 1.03 | .093 | 0.816 | 0.62, 1.07 | .137 | 1.063 | 0.81, 1.39 | .661 | |||
| >90 | 1.515 | 0.99, 2.31 | .054 | 1.878 | 1.03, 3.42 | .040* | 0.902 | 0.50, 1.61 | .729 | |||
| Sex (male) | 0.825 | 0.69, 0.99 | .037* | 0.823 | 0.66, 1.03 | .092 | 0.874 | 0.64, 1.19 | .400 | |||
| Race (non-White) | 1.500 | 1.04, 2.16 | .030* | 1.090 | 0.59, 2.01 | .783 | 0.940 | 0.58, 1.52 | .800 | |||
| Education (ref.: less than or equal to HS) | ||||||||||||
| Some college | 0.927 | 0.74, 1.17 | .522 | 0.947 | 0.70, 1.28 | .720 | 0.650 | 0.44, 0.95 | .028* | |||
| College graduate | 0.970 | 0.74, 1.28 | .827 | 1.028 | 0.73, 1.44 | .872 | 1.083 | 0.66, 1.79 | .755 | |||
| Professional/graduate | 1.200 | 0.95, 1.52 | .131 | 1.206 | 0.89, 1.64 | .230 | 0.764 | 0.52, 1.13 | .174 | |||
| Study site (ref: Wake Forest) | ||||||||||||
| UC Davis | 0.895 | 0.71, 1.13 | .358 | 1.023 | 0.75, 1.40 | .885 | 1.149 | 0.79, 1.67 | .469 | |||
| Johns Hopkins | 1.073 | 0.82, 1.41 | .610 | 1.205 | 0.85, 1.71 | .299 | 1.176 | 0.76, 1.83 | .473 | |||
| Pittsburgh | 0.682 | 0.53, 0.88 | .003** | 0.750 | 0.54, 1.04 | .088 | 0.737 | 0.50, 1.09 | .126 | |||
| Treatment group | 1.103 | 0.93, 1.31 | .267 | 1.032 | 0.83, 1.28 | .778 | 1.106 | 0.83, 1.48 | .497 | |||
| Medical comorbidities | 1.108 | 1.02, 1.20 | .010* | 1.166 | 1.06, 1.29 | .002** | 1.015 | 0.89, 1.16 | .829 | |||
| Depressive symptoms (CES-D ≥ 10) |
1.782 | 1.35, 2.35 | <.001*** | 1.957 | 1.37, 2.79 | <.001*** | 0.990 | 0.63, 1.55 | .963 | |||
| Mean cross-validated AUC | .673 | .728 | ||||||||||
Notes: AUC = area under the curve; CES-D = Center for Epidemiologic Studies Depression Scale; CI = confidence interval; HR = hazard ratio; HS = high school; MCI = mild cognitive impairment. Model 1 is unadjusted for covariates. Model 2 is adjusted for demographic (baseline age, study site, treatment group, sex, race, education category) and health covariates (medical comorbidities, significant depressive symptoms). Model 3 is stratified by MCI status. Individuals were assigned to the class of the highest posterior probability of membership. Mean 10-fold cross-validated area under the receiver operating characteristic curves are reported for nonstratified models.
*p < .05. **p < .01. ***p < .001, all p values are 2-sided.