Table 1. Characteristics of Participants at Age 55 Years.
| Characteristic | No. (%) | P value | ||
|---|---|---|---|---|
| Total cohort (N = 1091)a | 10-Year change in physical component score | |||
| ≥8-point decline (n = 206) | Increase or no significant change (n = 885) | |||
| Age, median (IQR), y | 54.8 (54.3-55.4) | 54.7 (54.3-55.4) | 54.8 (54.3-55.4) | .94 |
| BMI, median (IQR) | 27.0 (23.2-32.6) | 29.6 (24.7-35.6) | 26.3 (22.9-31.6) | <.001 |
| No health insurance | 40 (3.7) | 12 (5.8) | 26 (3.3) | .06 |
| Race or ethnicityb | ||||
| Black | 264 (24.2) | 65 (31.6) | 199 (22.5) | .02 |
| Chinese | 126 (11.6) | 22 (10.7) | 104 (11.8) | |
| Japanese | 135 (12.4) | 16 (7.8) | 119 (13.5) | |
| White | 566 (51.9) | 103 (50.0) | 463 (52.3) | |
| Menopausal status | ||||
| Postmenopausal | .75 | |||
| Surgical | 56 (5.0) | 10 (4.9) | 44 (5.0) | |
| Natural | 733 (67.3) | 141 (68.5) | 592 (67.0) | |
| Perimenopausal | ||||
| Late | 111 (10.2) | 18 (8.7) | 93 (10.5) | |
| Early | 119 (10.9) | 26 (12.6) | 93 (10.5) | |
| Unknown | ||||
| Hormone therapy | 50 (4.6) | 9 (4.4) | 41 (4.6) | |
| Posthysterectomy | 22 (2.2) | 2 (1.0) | 20 (2.3) | |
| Smoking status | ||||
| Never | 669 (61.4) | 109 (52.9) | 560 (63.4) | .003 |
| Current | 108 (9.9) | 32 (15.5) | 76 (8.6) | |
| Past | 312 (28.7) | 65 (31.6) | 247 (28.0) | |
| Alcohol use, drinks/wk | ||||
| None | 460 (42.2) | 99 (48.1) | 361 (40.8) | .12 |
| <1 | 269 (24.7) | 39 (18.9) | 230 (26.0) | |
| 1-7 | 187 (17.1) | 31 (15.1) | 156 (17.6) | |
| >7 | 75 (6.9) | 14 (6.8) | 61 (6.9) | |
| No answer given | 100 (9.2) | 23 (11.2) | 77 (8.7) | |
| Education | ||||
| ≥College | 550 (50.6) | 76 (36.9) | 474 (53.8) | <.001 |
| ≤High school | 537 (49.4) | 130 (63.1) | 407 (46.2) | |
| Difficulty paying for basics | 245 (22.5) | 64 (31.1) | 181 (20.5) | .001 |
| Sleep disturbancec | 500 (45.8) | 105 (51.0) | 395 (44.6) | .10 |
| Comorbid conditions present | ||||
| Diabetes | 163 (14.9) | 40 (19.4) | 123 (13.9) | .045 |
| Hypertension | 473 (43.4) | 108 (52.4) | 365 (41.2) | .006 |
| Hyperlipidemia | 579 (53.1) | 118 (57.3) | 461 (52.1) | .18 |
| Cardiovascular disease | 142 (13.0) | 40 (19.42) | 102 (11.53) | .002 |
| Osteoarthritis | 536 (49.1) | 116 (56.3) | 420 (47.5) | .02 |
| Osteoporosis | 181 (16.6) | 23 (11.2) | 158 (17.6) | .02 |
| Thyroid disease | 272 (24.9) | 55 (26.7) | 217 (24.5) | .51 |
| Cancer | 68 (6.2) | 13 (6.3) | 55 (6.2) | .96 |
| Depressive symptomsd | 165 (15.1) | 47 (22.8) | 118 (13.3) | <.001 |
| Physical component score, median (IQR) | 53.1 (46.8-56.7) | 53.3 (48.2-57.2) | 53.1 (46.6-56.6) | .02 |
| Kaiser Physical Activity Score, median (IQR) | 7.6 (6.2-8.8) | 7.3 (5.9-8.6) | 7.6 (6.3-8.9) | .006 |
| Blood pressure, median (IQR), mm Hg | ||||
| Systolic | 115 (105-126) | 119 (107-129) | 114 (105-125) | .008 |
| Diastolic | 73 (67-80) | 75 (68-80) | 73 (67-80) | .19 |
| hsCRP, median (IQR), mg/L | 1.7 (0.6-5.3) | 2.4 (0.9-6.8) | 1.6 (0.6-4.8) | .04 |
| Skeletal muscle mass, median (IQR)e | 1.6 (1.4-1.7) | 1.6 (1.5-1.8) | 1.6 (1.4-1.7) | .001 |
| Prescription medications used, median (IQR), No. | 2.0 (0.0-3.0) | 2.0 (1.0-4.0) | 2.0 (0.0-3.0) | .08 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); hsCRP, high-sensitivity C-reactive protein.
Missing data included 2 participants for smoking status, 100 participants for alcohol use, 2 participants for insurance status, 4 participants for education, 2 participants for Kaiser Physical Activity Score, 1 participant for hsCRP, and 2 participants for BMI.
The race and ethnicity categories were developed in the 1990s and do not adequately characterize all Chinese and Japanese ethnicities.
Sleep disturbance was defined as at least 3 nights per week of difficulty initiating sleep, difficulty remaining asleep, or early morning awakenings.
Depressive symptoms were defined as a score of 16 or greater on the Center for Epidemiology Study–Depression scale.
Skeletal muscle mass is a unitless quotient estimated in SWAN using bioelectrical impedance based on whole body muscle mass using previously published equations including height, conductance, sex, and age; this unitless measure is then standardized by dividing it by the square root of height.