Table 1.
Baseline characteristics among dialysis patients stratified by residential ultraviolet (UV) index category.
| UV Index | |||||||
|---|---|---|---|---|---|---|---|
| Total n= 47,286 | <3 (n=595) | 3–<5 (n= 19,941) | 5–<6 (n= 18,630) | 6–<7 (n= 7,206) | 7+ (n= 914) | p-value | |
| Age, mean (SD) | 60 (16) | 60 (16) | 60 (16) | 59 (16) | 60 (16) | 61 (16) | 0.2 |
| Female (%) | 46 | 40 | 45 | 50 | 44 | 41 | 0.9 |
| Diabetes mellitus (%) | 56 | 49 | 54 | 49 | 58 | 55 | <0.001 |
| Dialysis Modality (%) | |||||||
| Hemodialysis | 95 | 93 | 96 | 94 | 94 | 99 | 0.01 |
| Peritoneal Dialysis | 5 | 7 | 4 | 6 | 6 | 1 | |
| Race and Ethnicity (%) | |||||||
| White | 27 | 50 | 31 | 22 | 30 | 13 | <0.001 |
| Black | 41 | 22 | 50 | 35 | 30 | 39 | <0.001 |
| Hispanic | 21 | 4 | 9 | 28 | 31 | 45 | <0.001 |
| Asian | 4 | 10 | 2 | 7 | 4 | ~0 | <0.001 |
| Other | 6 | 12 | 6 | 7 | 5 | 3 | <0.001 |
| Vintage (%) | |||||||
| <6 months | 12 | 6 | 12 | 8 | 21 | 15 | <0.001 |
| 6–<24 months | 29 | 25 | 29 | 22 | 46 | 32 | <0.001 |
| 2–<5 years | 35 | 41 | 35 | 40 | 22 | 30 | <0.001 |
| ≥5 years | 24 | 28 | 24 | 29 | 11 | 23 | <0.001 |
| Primary Insurance (%) | |||||||
| Medicare | 58 | 49 | 61 | 55 | 60 | 52 | <0.001 |
| Medicaid | 8 | 3 | 7 | 10 | 8 | 5 | <0.001 |
| Private Insurance | 10 | 24 | 8 | 13 | 4 | 11 | <0.001 |
| Other | 14 | 16 | 15 | 10 | 23 | 28 | <0.001 |
| Marital Status (%) | |||||||
| Married | 36 | 44 | 34 | 35 | 44 | 41 | <0.001 |
| Divorced | 6 | 4 | 7 | 6 | 7 | 10 | 0.007 |
| Single | 28 | 26 | 30 | 25 | 29 | 26 | <0.001 |
| Widowed | 11 | 10 | 12 | 11 | 12 | 10 | 0.09 |
| spKt/V, mean (SD) | 1.50 (0.35) | 1.61 (0.32) | 1.48 (0.33) | 1.49 (0.35) | 1.53 (0.39) | 1.59 (0.36) | <0.001 |
| Residual Renal Function (ml/min), mean (SD) | 2.77 (2.5) | 1.99 (1.7) | 2.64 (2.50) | 2.60 (2.25) | 3.26 (2.90) | 3.30 (2.39) | <0.001 |
| Comorbidities (%) | |||||||
| Active Smoking | 4 | 4 | 5 | 3 | 3 | 2 | <0.001 |
| AHD | 16 | 19 | 18 | 13 | 16 | 24 | <0.001 |
| Alcohol Dependence | 1 | 1 | 1 | 1 | 1 | 1 | <0.001 |
| Cardiac Failure | 23 | 20 | 24 | 22 | 24 | 30 | 0.09 |
| COPD | 4 | 5 | 4 | 3 | 4 | 4 | <0.001 |
| CVD | 6 | 7 | 7 | 5 | 6 | 7 | 0.004 |
| Drug Use | 1 | 1 | 2 | 1 | 1 | 1 | <0.001 |
| Non-ambulatory State | 3 | 1 | 3 | 3 | 3 | 4 | <0.001 |
| Malignancy | 3 | 3 | 4 | 2 | 3 | 5 | <0.001 |
| PVD | 8 | 10 | 9 | 6 | 9 | 16 | 0.002 |
| Serum or Blood Levels, mean (SD) | |||||||
| Ferritin (ng/mL) | 526 (504) | 519 (411) | 497 (479) | 566 (533) | 481 (483) | 582 (521) | <0.001 |
| Hemoglobin (g/dL) | 11.9 (1.4) | 12.0 (1.2) | 11.9 (1.4) | 11.9 (1.3) | 12.1(1.4) | 12.2 (1.2) | <0.001 |
| TIBC (mg/dL) | 208 (46) | 211 (46) | 208 (47) | 206 (46) | 214 (46) | 204 (41) | <0.001 |
| Albumin (g/dL) | 3.67 (0.47) | 3.71 (0.44) | 3.67 (0.48) | 3.69 (0.46) | 3.65 (0.48) | 3.72 (0.45) | 0.3 |
| Calcium (mg/dL) | 9.2 (0.7) | 9.3 (0.8) | 9.2 (0.7) | 9.2 (0.7) | 9.2 (0.7) | 9.3 (0.7) | 0.5 |
| Intact PTH (pg/ml) | 375 (391) | 340 (347) | 384 (405) | 369 (380) | 366 (377) | 447 (493) | 0.006 |
| Phosphorus (mg/dL) | 5.6 (1.5) | 5.8 (1.5) | 5.6 (1.5) | 5.6 (1.5) | 5.5 (1.5) | 5.6 (1.4) | 0.5 |
| Creatinine (mg/dL) | 8.5 (3.5) | 8.9 (3.3) | 8.6 (3.5) | 8.7 (3.6) | 7.6 (3.3) | 8.8 (3.5) | <0.001 |
| nPCR (g/kg/day) | 0.96 (0.26) | 0.97 (0.26) | 0.94 (0.25) | 0.97 (0.26) | 0.94 (0.26) | 1.00 (0.27) | 0.002 |
| BMI (kg/m2) | 26.6 (6.9) | 26.7 (8.0) | 26.8 (7.0) | 26.4 (6.9) | 26.6 (6.5) | 26.6 (6.3) | 0.1 |
| WBC (×103/ul) | 7.3 (2.4) | 7.7 (2.8) | 7.3 (2.5) | 7.4 (2.4) | 7.5 (2.3) | 7.4 (2.3) | <0.001 |
| Lymphocyte % | 21 (8) | 20 (8) | 21 (8) | 21 (8) | 21 (8) | 23 (8) | <0.001 |
| Bicarbonate (mg/dL) | 22.4 (3.1) | 23.2 (3.4) | 22.2 (3.1) | 22.5 (3.0) | 22.9 (3.2) | 22.1 (3.1) | <0.001 |
*
p-values were calculated using non-parametric tests of linear trend.
Abbreviations: SD: standard deviation; AHD: atherosclerotic disease; COPD: chronic-obstructive pulmonary disease; CVD: cerebrovascular disease; PVD: peripheral vascular disease; TIBC: total iron binding capacity; PTH: parathyroid hormone; nPCR: normalized protein catabolic rate; BMI: body mass index; WBC: white blood cell count