Table 1. Demographic, clinical, and laboratory parameters of the study population by tertiles of fibroblast growth factor 23 levels.
| Characteristics | All sample (n=144) | FGF23 (RU/mL) | p value | ||
|---|---|---|---|---|---|
| 1st tertile <54.4 (n=47) | 2nd tertile 54.4-92.6 (n=48) | 3rd tertile ≥92.6 (n=49) | |||
| Age, years | 85.4±4.1 | 85.6±3.8 | 84.1±3.0a | 86.6±4.9b | 0.011 |
| Gender | 0.931 | ||||
| Male | 38 (26.4) | 13 (27.7) | 13 (27.1) | 12 (24.5) | |
| Female | 106 (73.6) | 34 (72.3) | 35 (72.9) | 37 (75.5) | |
| Race | 0.069 | ||||
| White | 96 (66.7) | 26 (55.3) | 32 (66.7) | 38 (77.6) | |
| Non-white | 48 (33.3) | 21 (44.7) | 16 (33.3) | 11 (22.4) | |
| Number of chronic disease | 4.4±1.9 | 3.9±1.9a | 4.5±1.6 | 4.9±2.0b | 0.018 |
| Number of regular use medications | 5.9±2.7 | 4.9±2.1a | 6.2±2.6b | 6.5±3.1b | 0.008 |
| Vitamin D supplements | 59 (41.3) | 15 (31.9) | 23 (47.9) | 21 (43.8) | 0.260 |
| Weight, kg | 70.7±78.9 | 65.1±12.5 | 82.4±135.6 | 64.7±13.8 | 0.687 |
| Body mass index, kg/m2 | 26.8±4.3 | 27.4±4.0 | 26.5±4.1 | 26.5±4.9 | 0.562 |
| 25(OH)D, ng/mL | 19.2±8.4 | 19.6±8.6 | 20.8±9.6 | 17.3±6.4 | 0.110 |
| 25(OH)D – category, ng/mL | 0.183 | ||||
| <20ng/mL | 85 (59.0) | 26 (55.3) | 25 (52.1) | 34 (69.4) | |
| ≥20ng/mL | 59 (41.0) | 21 (44.7) | 23 (47.9) | 15 (30.6) | |
| PTH, pg/mL | 62.6±33.4 | 53.9±29.2 | 63.1±27.8 | 70.5±40.0 | 0.060* |
| Calcium, mg/dL | 9.3±0.5 | 9.3±0.5 | 9.4±0.4 | 9.4±0.5 | 0.428 |
| Phosphorus, mg/dL | 3.4±1.1 | 3.2±0.5 | 3.3±0.4 | 3.7±1.8 | 0.091* |
| Hemoglobin, g/dL | 13.4±1.3 | 13.9±1.2b | 13.3±1.3a | 13.1±1.3a | 0.012 |
| Creatinine, mg/dL | 0.96±0.28 | 0.87±0.19a | 0.97±0.24b | 1.04±0.35b | 0.007 |
| Cystatin C, mg/L | 1.50±0.37 | 1.32±0.28c | 1.49±0.29a | 1.69±0.43b | <0.001 |
| eGFR, mL/minute/1.73m2 | 51±14 | 58±12b | 50±12a | 45±14a | <0.001 |
| eGFR – category, mL/minute/1.73 m2 | <0.001 | ||||
| <45mL/minute/1.73m2 | 48 (33.3) | 6 (12.8)a | 17 (35.4) | 25 (51.0)b | |
| ≥45mL/minute/1.73m2 | 96 (66.7) | 41 (87.2) | 31 (64.6) | 24 (49.0) | |
| Functional capacity | |||||
| Education, years | 4.5±3.8 | 4.4±3.7 | 5.1±4.6 | 3.9±2.9 | 0.720* |
| GDS | 3.9±2.7 | 3.4±2.2 | 3.9±2.9 | 4.4±2.8 | 0.259* |
| MMSE | 24.2±3.4 | 23.7±3.2 | 24.5±3.6 | 24.5±3.3 | 0.466 |
| VFT | 12.9±3.5 | 12.5±3.4 | 12.9±3.6 | 13.3±3.7 | 0.562 |
| IADL | 18.8±2.5 | 19.0±2.6 | 19.3±2.1 | 18.2±2.8 | 0.156* |
| Handgrip strength, kgf† | |||||
| All | 21.8±9.0 | 23.5±12.4 | 21.6±6.3 | 20.5±7.2 | 0.283 |
| Male | 30.2±11.4 | 35.0±17.1 | 27.5±5.7 | 28.0±6.2 | 0.130* |
| Female | 18.8±5.4 | 18.9±5.6 | 19.3±5.0 | 18.1±5.6 | 0.612 |
| Time to stand up and sit down, seconds‡ | 20.3±8.4 | 22.1±10.4 | 19.2±7.6 | 19.6±6.7 | 0.451* |
Results expressed are mean (± standard deviation), n (%).
Different letters have different means from multiple comparisons.
* p value: descriptive level of χ2 test or Kruskal-Wallis/analysis of variance; † n=143 (male/female: 38/105); ‡ n=136 (of 140 tested, 136 fulfilled the task).
FGF23: fibroblast growth factor 23; 25(OH) vit D: 25(OH) vitamin D; PTH: parathyroid hormone; eGFR: estimated glomerular filtration rate; GDS: Geriatric Depression Scale; MMSE: Mini-Mental State Examination; VFT: Verbal Fluency Test; IADL: Instrumental Activity Daily Living.