Table 2.
Independent Associations between Observed Agitation and Lighting Treatment, Resident Characteristics, and Selected Environmental Factors: Results of a Logistic Mixed Model (N=66 residents, 10,001 observations)*
| Variable | Odds Ratio (95% CI) for Observed Agitation |
p-value | |
|---|---|---|---|
| Treatment Pair Comparisons† | |||
| Mild/moderate dementia | <0.001† | ||
| AM light vs. Standard | 1.57 | (1.18, 2.08) | 0.003 |
| PM light vs. Standard | 1.90 | (1.42, 2.55) | <0.001 |
| All Day vs. Standard | 1.63 | (1.22, 2.18) | 0.001 |
| AM light vs. PM light | 0.82 | (0.64, 1.07) | 0.143 |
| AM light vs. All Day light | 0.96 | (0.74, 1.24) | 0.747 |
| PM light vs. All Day light | 1.17 | (0.90, 1.52) | 0.257 |
| Severe/very severe dementia | 0.247‡ | ||
| AM light vs. Standard | 1.22 | (1.00, 1.49) | 0.055 |
| PM light vs. Standard | 1.11 | (0.90, 1.36) | 0.328 |
| All Day vs. Standard | 1.05 | (0.86, 1.29) | 0.638 |
| AM light vs. PM light | 1.10 | (0.90, 1.34) | 0.342 |
| AM light vs. All Day light | 1.16 | (0.95, 1.42) | 0.147 |
| PM light vs. All Day light | 1.06 | (0.86, 1.29) | 0.602 |
| Oregon site | 1.43 | (0.61, 3.34) | 0.411 |
| Female gender | 1.47 | (0.68, 3.18) | 0.337 |
| Mild/moderate dementia (Standard light) | 0.36 | (0.18, 0.72) | 0.005§ |
| Time of day (Reference: 8 AM – Noon) | <0.001∥ | ||
| Noon – 4 PM | 1.26 | (1.10, 1.44) | 0.002 |
| 4 PM – 8 PM | 1.81 | (1.58, 2.07) | <0.001 |
| Day length (hrs) | 1.03 | (0.98, 1.08) | 0.259 |
| Rate of change of day length (min/day) | 0.98 | (0.94, 1.02) | 0.237 |
| Daily sedative load (per 10 units) | 1.04 | (0.96, 1.14) | 0.349 |
| Daily analgesic load (per 10 units) | 1.33 | (0.99, 1.77) | 0.061 |
Because a significant (p=0.019) dementia severity-by-treatment interaction effect was present, the mixed model estimates separate treatment effects for mild/moderate and severe/very severe dementia. The mixed model includes resident random effect and all fixed effects shown; thus, all values are adjusted for other variables shown. The estimate (SE) for the resident variance is 1.271 (0.282), p<0.001.
AM light = 7AM – 11AM high intensity light; PM light = 4 PM – 8 PM high intensity light; All Day light = 7 AM – 8 PM high intensity light; Standard = recommended minimum Standard lighting for task areas for older persons (500–600 lux)
P-value for overall F test (3 df) for lighting treatment (for mild/moderate and severe/very severe dementia respectively).
P-value for mild/moderate vs. severe/very severe dementia is 0.030 for AM light, 0.178 for PM light, and 0.103 for All Day light.
P-value for overall F test (2 df) for time of day; the p-value for Noon-4PM vs. 4–8 PM is <0.001.