Table 1.
Characteristics of CKD patients by 25(OH)D measurement status
| Variable | 25(OH)D Not measured |
25(OH)D ≥30 ng/ml |
25(OH)D 15–29 ng/ml |
25(OH)D <15 ng/ml |
|---|---|---|---|---|
| No. | 33573 | 5044 | 5749 | 1970 |
| Age (y) | 72.9 +/− 11.8** | 72.3 +/− 11.1*** | 71.6 +/− 11.7*** | 69.3 +/− 12.9*** |
| eGFR (mL/min/1.73 m2) | 46.6 +/− 10.2** | 48.1 +/− 9.2*** | 47.5 +/− 9.8*** | 45.2 +/− 10.7*** |
| CKD stage | ||||
| 3a (eGFR = 45–59 ml/min/1.73 m2) | 21189 (63)* | 3547 (70)*** | 3953 (69)*** | 1159 (59)*** |
| 3b (eGFR = 30–44 ml/min/1.73 m2) | 9264 (28)* | 1220 (24)*** | 1359 (24)*** | 584 (30)*** |
| 4 (eGFR = 15–29 ml/min/1.73 m2) | 3120 (9)* | 277 (5)*** | 437 (8)*** | 227 (12)*** |
| No. of encounters in EHR | 160 +/− 127** | 233 +/− 161*** | 244 +/− 164*** | 267 +/− 182*** |
| Male gender, | 16726 (50)* | 1470 (29)*** | 2112 (37)*** | 660 (34)*** |
| African Americans, | 3867 (12)* | 415 (8)*** | 670 (12)*** | 556 (28)*** |
| Diabetes, | 6435 (19)* | 986 (20)*** | 1626 (28)*** | 777 (39)*** |
| Hypertension, | 26428 (79)* | 4569 (91)*** | 5270 (92)*** | 1844 (94)*** |
| Coronary artery disease, | 6833 (20)* | 877 (17)*** | 1190 (20)*** | 398 (20)*** |
| Cerebrovascular disease, | 2765 (8)* | 463 (9) | 534 (9) | 221 (11) |
| Congestive heart failure, | 2802 (8)* | 283 (6)*** | 338 (6)*** | 171 (8)*** |
| Malignancy, | 7835 (23)* | 989 (20) | 1098 (19) | 314 (16) |
| Hyperlipidemia, | 24447 (73)* | 4146 (82) | 4752 (83) | 1594 (81) |
| BMI Category | ||||
| <18.5 kg/m2 | 423 (1)* | 75 (1)*** | 42 (1)*** | 28 (1)*** |
| 18.5–24.9 kg/m2 | 7627 (23)* | 1495 (30)*** | 1152 (20)*** | 314 (16)*** |
| 25–29.9 kg/m2 | 11021 (33)* | 1875 (37)*** | 2026 (35)*** | 569 (29)*** |
| 30–34.9 kg/m2 | 6603 (20)* | 873 (17)*** | 1349 (23)*** | 453 (23)*** |
| 35–39.9 kg/m2 | 2787 (8)* | 348 (7)*** | 606 (11)*** | 280 (14)*** |
| ≥40 kg/m2 | 1866 (6)* | 193 (4)*** | 389 (7)*** | 265 (13)*** |
| Missing | 3246 (10)* | 185 (4)*** | 185 (3)*** | 61 (3)*** |
| Albumin (g/dl) | 4.21 +/− 0.36*** | 4.16 +/− 0.38*** | 4.05 +/− 0.47*** | |
| Hemoglobin (g/dl) | 13.0 +/− 1.5*** | 12.9 +/− 1.7*** | 12.4 +/− 1.7*** | |
| Phosphorus (mg/dl) | 3.58 +/− 0.68*** | 3.60 +/− 0.73*** | 3.71 +/− 0.91*** |
Note: 25(OH)D measurement status based on tests performed after CKD was confirmed. Continuous variables given as mean +/− SD; categorical variables as number (percentage). Conversion factors for units: albumin and hemoglobin in g/dL to g/L, ×10; phosphorus in mg/dL to mmol/L, ×0.3229.
Chi-square P≤0.01
t-test P≤0.01 comparing patients with 25(OH)D measured vs all those not measured.
P<0.05 for differences among 3 measured 25(OH)D groups with. Mantel-Haenszel Chi-square used to assess binary and ordered categorical variables against 3 ordered levels of vitamin D and ANOVA used for continuous variable.
Abbreviations: BMI, body mass index; CKD: chronic kidney disease, 25(OH)D: 25-hydroxy vitamin D, EHR, electronic health record; eGFR: estimated glomerular filtration rate