Table 4.
Cox proportional hazards model for insomnia symptoms as a predictor of time-to-onset of dementia diagnosis – 2006–2016 Health and Retirement Study (n=6,907)
| Unadjusted | Model I a | Model II b | Model III c | |||||
|---|---|---|---|---|---|---|---|---|
| HR | 95% CI | HR | 95% CI | HR | 95% CI | HR | 95% CI | |
| Insomnia symptoms: | ||||||||
| Any: | ||||||||
| Yes | 1.12 | 0.97, 1.30 | 1.06 | 0.91, 1.24 | 1.04 | 0.90, 1.22 | 0.98 | 0.83, 1.15 |
| No | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Continuous | 1.04 | 1.00, 1.08 | 1.01 | 0.98, 1.05 | 1.01 | 0.98, 1.05 | 0.99 | 0.95, 1.03 |
| Severe: | ||||||||
| Yes | 0.92 | 0.77, 1.09 | 0.98 | 0.82, 1.19 | 0.98 | 0.81, 1.17 | 0.99 | 0.83, 1.20 |
| No | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Continuous | 0.95 | 0.88, 1.02 | 0.98 | 0.92, 1.05 | 0.98 | 0.92, 1.05 | 0.99 | 0.93, 1.07 |
| Change in insomnia symptoms (Any): | ||||||||
| 2006–2010: | ||||||||
| Increase | 1.34 | 1.10, 1,64 | 1.24 | 1.01, 1.52 | 1.26 | 1.03, 1.54 | 1.27 | 1.03, 1.55 |
| No change | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 1.51 | 1.23, 1.86 | 1.41 | 1,14, 1.74 | 1.41 | 1.14, 1.74 | 1.36 | 1.09, 1.69 |
| 2010–2014: | ||||||||
| Increase | 0.86 | 0.68, 1.10 | 0.82 | 0.64, 1.04 | 0.81 | 0.64, 1.04 | 0.78 | 0.61, 1.00 |
| No change | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 1.38 | 1.11, 1.73 | 1.25 | 1.00, 1.56 | 1.25 | 0.99, 1.57 | 1.20 | 0.96, 1.52 |
| 2006–2014: | ||||||||
| Increase | 0.86 | 0.67, 1.10 | 0.82 | 0.64, 1.04 | 0.81 | 0.64, 1.04 | 0.78 | 0.61, 1.00 |
| No change | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 1.38 | 1.11, 1.72 | 1.25 | 1.00, 1.56 | 1.25 | 0.99, 1.57 | 1.21 | 0.96, 1.52 |
| Change in insomnia symptoms (Severe): | ||||||||
| 2006–2010: | ||||||||
| Increase | 1.65 | 1.38, 1.99 | 1.59 | 1.33, 1.92 | 1.58 | 1.31, 1.90 | 1.58 | 1.31, 1.90 |
| No change | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 1.22 | 1.02, 1.46 | 1.16 | 0.97, 1.39 | 1.15 | 0.96, 1.37 | 1.15 | 0.95, 1.38 |
| 2010–2014: | ||||||||
| Increase | 1.54 | 1.27, 1.88 | 1.47 | 1.22, 1.79 | 1.48 | 1.21, 1.80 | 1.47 | 1.21, 1.80 |
| No change | 0.97 | 0.76, 1.22 | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 0.97 | 0.76, 1.22 | 0.96 | 0.75, 1.21 | 0.95 | 0.74, 1.21 | ||
| 2006–2014: | ||||||||
| Increase | 1.59 | 1.31, 1.96 | 1.48 | 1.21, 1.82 | 1.47 | 1.19, 1.80 | 1.45 | 1.18, 1.79 |
| No change | Ref. | -- | Ref. | -- | Ref. | -- | Ref. | -- |
| Decrease | 0.88 | 0.71, 1.09 | 0.88 | 0.70, 1.82 | 0.86 | 0.68, 1.07 | 0.85 | 0.68, 1.07 |
Abbreviations: HR=hazard ratio; CI: confidence interval.
a
Model I was adjusted for socio-demographic characteristics;
b
Model II was adjusted for socio-demographic and lifestyle characteristics;
c
Model III was adjusted for socio-demographic, lifestyle and health characteristics.