Table 1.
Baseline Characteristics of Participants for Overall Cohort by Averaged Sleep Efficiency
| Quartilea of Averaged Sleep Efficiency, % |
|||||||
|---|---|---|---|---|---|---|---|
| Characteristic | Overall (N=1245) | Q1 (N=311) | Q2 (N=311) | Q3 (N=311) | Q4 (N=312) | P-valueb | χ2 [d.f, N] or F-value [d.f] |
| Age, years, mean (SD) | 82.63 (3.32) | 82.2 (3.70) | 82.63 (3.36) | 82.91 (3.27) | 82.77 (2.85) | 0.04 | F = 2.73 [3, 1241] |
| Caucasian, n (%) | 1109 (89.08) | 243 (78.14) | 276 (88.75) | 292 (93.89) | 298 (95.51) | <0.001 | χ2 = 58.99 [3, 1245] |
| Self-reported health status, n (%) | <0.001 | χ2 = 23.76 [6, 1245] | |||||
| Poor/very poor | 16 (1.29) | 7 (2.25) | 6 (1.93) | 1 (0.32) | 2 (0.64) | ||
| Fair | 225 (18.07) | 72 (23.15) | 67 (21.54) | 40 (12.86) | 46 (14.74) | ||
| Good/excellent | 1004 (80.64) | 232 (74.60) | 238 (76.53) | 270 (86.82) | 264 (84.62) | ||
| Education, years, mean (SD) | 12.88 (2.57) | 12.73 (2.54) | 12.9 (2.54) | 12.86 (2.66) | 13.03 (2.53) | 0.54 | F = 0.71 [3, 1241] |
| Lives alone, n (%) | 734 (58.96) | 181 (58.20) | 184 (59.16) | 180 (57.88) | 189 (60.58) | 0.90 | χ2 = 0.57 [3, 1245] |
| Average drinks per week, mean (SD) | 1.12 (2.87) | 1.29 (3.67) | 1.02 (2.48) | 1.03 (2.35) | 1.16 (2.79) | 0.70 | χ2 = 1.42 [3, 1245] |
| Never smoked, n (%) | 824 (66.18) | 193 (62.06) | 200 (64.31) | 207 (66.56) | 224 (71.79) | 0.21 | χ2 = 8.46 [6, 1245] |
| Current antidepressant use, n (%) | 131 (10.52) | 42 (13.50) | 29 (9.32) | 28 (9.00) | 32 (10.26) | 0.24 | χ2 = 4.20 [3, 1245] |
| Current benzodiazepine use, n (%) | 84 (6.75) | 27 (8.68) | 19 (6.11) | 20 (6.43) | 18 (5.77) | 0.46 | χ2 = 2.57 [3, 1245] |
| Current prescription sleep medication use, n (%) | 14 (1.12) | 7 (2.25) | 2 (0.64) | 3 (0.96) | 2 (0.64) | 0.18 | χ2 = 4.92 [3, 1245] |
| # of medical conditionsc (0-8), mean (SD) | 1.39 (1.11) | 1.59 (1.16) | 1.41 (1.08) | 1.31 (1.12) | 1.25 (1.04) | <0.001 | χ2 = 16.78 [3, 1244] |
| GDS score (0-15), mean (SD) | 1.9 (2.21) | 2.34 (2.45) | 1.93 (2.29) | 1.62 (1.92) | 1.73 (2.10) | <0.001 | χ2 = 21.21 [3, 1243] |
| IADL impairments (0 - 6), mean (SD) | 1.12 (1.57) | 1.51 (1.76) | 1.11 (1.52) | 1.11 (1.59) | 0.76 (1.27) | <0.001 | χ2 = 32.33 [3, 1245] |
| BMI, kg/m2, mean (SD) | 27.5 (4.82) | 28.92 (5.26) | 27.67 (5.01) | 26.89 (4.47) | 26.53 (4.14) | <0.001 | F = 15.40 [3, 1235] |
| Walks for exercise, n (%) | 516 (41.88) | 119 (38.89) | 129 (41.75) | 142 (45.95) | 126 (40.91) | 0.34 | χ2 = 3.35 [3, 1232] |
| MMSE (0-30), mean (SD) | 28.49 (1.36) | 28.24 (1.43) | 28.48 (1.35) | 28.62 (1.36) | 28.61 (1.27) | 0.001 | χ2 = 15.97 [3, 1245] |
| Visit 9 3MS (0-100), mean (SD) | 88.10 (9.67) | 86.58 (9.83) | 88.46 (9.82) | 87.81 (10.75) | 89.56 (7.86) | <0.001 | χ2 = 19.81 [3, 1244] |
| Visit 9 cognitive status, n (%) | 0.03 | χ2 = 14.04 [6, 1245] | |||||
| Normal | 772 (62.01) | 177 (56.91) | 193 (62.06) | 190 (61.09) | 212 (67.95) | ||
| MCI | 290 (23.29) | 83 (26.69) | 63 (20.26) | 74 (23.79) | 70 (22.44) | ||
| Dementia | 183 (14.70) | 51 (16.40) | 55 (17.68) | 47 (15.11) | 30 (9.62) | ||
Abbreviations: GDS, Geriatric Depression Scale; IADL, instrumental activities of daily living; BMI, body mass index; MMSE, Mini-Mental State Examination; 3MS, Modified Mini-Mental State Examination; MCI, Mild Cognitive Impairment
Quartile cutpoints: 74.39, 81.84, 86.26
p-values for continuous variables are from ANOVA (F-statistic) for normally distributed variables, a Kruskall-Wallis test (χ2) for skewed data; p-values for categorical are data from a chi-square test for homogeneity (χ2).
Select medical conditions include history of cancer, stroke, diabetes, Parkinson's disease, chronic obstructive pulmonary disease, congestive heart failure, hypertension and coronary heart disease (angina/myocardial infarction)