Table 1. Baseline characteristics of the study population by trajectory group in 1993.
| Variables | Total (N = 2,300) | Starting low and declining (n = 664) | Starting high and declining (n = 1,276) | High-stable (n = 360) | p-valuea |
|---|---|---|---|---|---|
| Age, y, mean ± SD | 70.95 ± 5.04 | 72.89 ± 5.83 | 70.63 ± 4.61 | 68.50 ± 3.26 | <0.001 |
| 65–74, n (%) | 1812 (78.78) | 422 (63.55) | 1047 (82.05) | 343 (95.28) | <0.001 |
| ≥75, n (%) | 488 (21.22) | 242 (36.45) | 229 (17.95) | 17 (4.72) | |
| Female, n (%) | 1032 (44.87) | 473 (71.23) | 458 (35.89) | 101 (28.06) | <0.001 |
| Education, n (%) | <0.001 | ||||
| Illiterate | 883 (38.41) | 493 (74.36) | 356 (27.90) | 34 (9.44) | |
| Uneducated but literate | 185 (8.05) | 48 (7.24) | 115 (9.01) | 22 (6.11) | |
| Primary | 769 (33.45) | 104 (15.69) | 504 (39.50) | 161 (44.72) | |
| Secondary or above | 462 (20.10) | 18 (2.71) | 301 (23.59) | 143 (39.72) | |
| Health behavior, n (%) | |||||
| Take part in physical activity | 1507 (65.52) | 318 (47.89) | 921 (72.18) | 268 (74.44) | <0.001 |
| Smoking | 667 (29.00) | 112 (16.87) | 437 (34.25) | 118 (32.78) | <0.001 |
| Alcohol drinking | 447 (19.43) | 57 (8.58) | 285 (22.34) | 105 (29.17) | <0.001 |
| BMIb, kg/m2, mean ± SD | 22.83 ± 3.36 | 22.63 ± 3.52 | 22.93 ± 3.39 | 22.88 ± 2.96 | 0.17 |
| Normal | 1363 (60.44) | 402 (61.75) | 745 (59.79) | 216 (60.34) | 0.17 |
| Underweight | 159 (7.05) | 50 (7.68) | 84 (6.74) | 25 (6.98) | |
| Overweight | 480 (21.29) | 117 (17.97) | 277 (22.33) | 86 (24.02) | |
| Obese | 253 (11.22) | 82 (12.60) | 140 (11.24) | 31 (8.66) | |
| Self-rated health (0–5), mean ± SD | 3.44 ± 1.08 | 3.06 ± 1.10 | 3.56 ± 1.05 | 3.71 ± 0.99 | <0.001 |
| Good, n (%) | 1054 (46.13) | 217 (32.93) | 636 (50.20) | 201 (55.99) | <0.001 |
| Average, n (%) | 783 (34.27) | 229 (34.75) | 432 (34.10) | 122 (33.98) | |
| Poor, n (%) | 448 (19.61) | 213 (32.32) | 199 (15.71) | 36 (10.03) | |
| Chronic disease, n (%) | |||||
| Hypertension | 616 (27.49) | 192 (30.09) | 330 (26.40) | 94 (26.63) | 0.22 |
| Diabetes | 193 (8.64) | 64 (10.08) | 113 (9.08) | 16 (4.49) | 0.008 |
| Heart disease | 207 (10.08) | 63 (11.01) | 121 (10.51) | 23 (6.95) | 0.11 |
| CES-D (0–30), mean ± SD | 6.31 ± 5.71 | 8.08 ± 6.67 | 5.89 ± 5.19 | 4.52 ± 4.62 | <0.001 |
| Physical function, mean ± SD | |||||
| Mobility tasks (0–24) | 2.39 ± 3.91 | 4.31 ± 5.05 | 1.76 ± 3.16 | 1.11 ± 2.33 | <0.001 |
| ADLs (0–18) | 0.09 ± 0.76 | 0.26 ± 1.29 | 0.02 ± 0.39 | 0.01 ± 0.17 | <0.001 |
| IADLs (0–18) | 1.50 ± 2.85 | 3.28 ± 4.05 | 0.89 ± 1.89 | 0.43 ± 1.07 | <0.001 |
| Social support, mean ± SD | |||||
| Social interaction (0–2) | 0.75 ± 0.60 | 0.63 ± 0.54 | 0.79 ± 0.61 | 0.85 ± 0.65 | <0.001 |
| Emotional support (0–3) | 2.58 ± 0.75 | 2.49 ± 0.80 | 2.60 ± 0.76 | 2.69 ± 0.68 | <0.001 |
SD: standard deviation; BMI: body mass index; CES-D: Center for Epidemiologic Studies Depression Scale; ADL: activities of daily living; IADL: instrument activities of daily living.
aChi-square test or ANOVA were applied to test for differences among the three trajectory groups.
bUnderweight: BMI < 18.5 kg/m2; Normal: 18.5 ≤ BMI < 24 kg/m2; Overweight: 24 ≤ BMI < 27 kg/m2; Obese: BMI ≥ 27 kg/m2.