TABLE 1.
Baseline characteristics of Chinese adults aged ≥80 y by age-specific quartile of plasma 25(OH)D concentration1
| Plasma 25(OH)D concentrations | |||||
|---|---|---|---|---|---|
| Characteristics | AQ 12 | AQ 2 | AQ 3 | AQ 4 | P value |
| 3.26–29.2 nmol/L | 21.1–39.8 nmol/L | 29.3–53.3 nmol/L | 41.5–90.7 nmol/L | ||
| No. of participants | 547 | 547 | 545 | 546 | |
| Age, y | 94 (86–100) | 93 (87–100) | 93 (86–100) | 93 (86–100) | 0.86 |
| Female | 412 (75.3) | 385 (70.3) | 338 (62.0) | 278 (50.9) | <0.01 |
| Season of blood draw | — | — | — | — | <0.01 |
| March–May | 277 (50.6) | 193 (35.4) | 153 (28.1) | 125 (23.0) | |
| June–August | 269 (49.2) | 352 (64.5) | 381 (69.9) | 344 (63.2) | |
| September–November | 1 (0.2) | 1 (0.2) | 11 (2.0) | 75 (14.8) | |
| Residence in urban area | 74 (13.7) | 81 (14.9) | 70 (13.0) | 55 (10.2) | 0.12 |
| Education time ≥1, y | 87 (16.1) | 111 (20.4) | 123 (22.9) | 144 (26.6) | <0.01 |
| Current smoker | 41 (7.8) | 53 (10.0) | 47 (8.8) | 72 (13.4) | 0.04 |
| Current drinker | 49 (9.3) | 56 (10.5) | 72 (13.5) | 72 (13.5) | 0.07 |
| Vegetable intake | — | — | — | — | <0.01 |
| Often | 291 (55.2) | 339 (64.0) | 335 (63.0) | 259 (48.1) | |
| Not often | 236 (44.8) | 191 (36.0) | 202 (37.6) | 280 (52.0) | |
| Fruit intake | — | — | — | — | <0.01 |
| Often | 221 (41.9) | 220 (41.2) | 182 (33.8) | 166 (30.6) | |
| Not often | 306 (58.7) | 314 (58.8) | 357 (66.2) | 376 (69.4) | |
| Meat intake | — | — | — | — | <0.01 |
| Often | 292 (57.3) | 284 (54.3) | 256 (48.6) | 247 (46.5) | |
| Not often | 218 (42.8) | 239 (45.7) | 271 (51.4) | 284 (53.5) | |
| Currently engaged in physical exercise | 50 (9.7) | 54 (10.4) | 72 (13.4) | 82 (15.6) | 0.01 |
| Frailty3 | — | — | — | — | <0.01 |
| Robust | 133 (27.5) | 175 (35.1) | 168 (33.5) | 183 (36.9) | |
| Prefrail | 134 (27.8) | 158 (31.7) | 181 (36.1) | 200 (40.3) | |
| Frail | 216 (44.7) | 165 (33.1) | 153 (30.5) | 113 (22.8) | |
| Systolic blood pressure, mmHg | 140 (125–160) | 142 (125–160) | 140 (128–160) | 140 (128–160) | 0.85 |
| MMSE | 20.0 (7.0–25.0) | 22.0 (12.0–26.0) | 24.0 (15.0–28.0) | 25.0 (19.0–28.0) | <0.01 |
| BMI, kg/m2 | 20.0 (17.6–22.5) | 20.0 (17.9–22.8) | 20.0 (17.8–23.1) | 20.1 (18.0–22.4) | 0.79 |
| Plasma glucose, mmol/L | 4.70 (4.10–5.55) | 4.69 (4.06–5.47) | 4.70 (4.01–5.40) | 4.65 (3.83–5.41) | 0.38 |
| Plasma total cholesterol, mmol/L | 4.34 (3.64–5.09) | 4.33 (3.63–5.05) | 4.31 (3.61–5.02) | 4.27 (3.77–4.90) | 0.88 |
| Plasma triglycerides, mmol/L | 0.85 (0.64–1.18) | 0.86 (0.63–1.20) | 0.88 (0.65–1.30) | 0.85 (0.64–1.14) | 0.09 |
| Plasma albumin, mmol/L | 39.3 (36.0–42.5) | 40.2 (37.0–43.7) | 40.6 (37.3–43.6) | 40.5 (37.6–43.1) | <0.01 |
| Plasma high sensitivity C-reactive protein, mmol/L | 1.24 (0.49–3.35) | 1.00 (0.44–2.73) | 1.03 (0.44–2.68) | 1.23 (0.47–2.72) | 0.07 |
| Plasma creatinine, µmol/L | 71.0 (61.1–87.0) | 76.9 (64.0–93.2) | 79.0 (67.0–93.4) | 84.3 (68.0–101.8) | <0.01 |
Continuous variables are expressed as medians and IQRs; categorical variables are expressed as frequencies (percentages). For details on the age ranges and plasma 25(OH)D concentration ranges, please refer to Supplemental Table 1. AQ, age-specific quartile; 25(OH)D, 25-hydroxyvitamin D.
Age-specific quartile ranges were derived from the combination of corresponding quartiles in different age group (octogenarian, nonagenarian, and centenarian). Therefore, each quartile consists of the corresponding quartiles of all age groups. For details, please refer to specific ranges in Supplemental Table 1.
Frailty was defined according to the Study of Osteoporotic Fractures index using 3 components: 1) low body weight (BMI <18.5 kg/m2); 2) inability to rise from a chair without using one's arms; and 3) reduced energy, as indicated by a response of “yes” to the following question: “For the last 6 mo, were you limited in activities because of a health problem?” Frailty status was defined as robust (0 components, reference), prefrail (1 component), or frail (2 or 3 components).