Table 1.
Baseline characteristics stratified by Δ serum ferritin in 93,979 incident HD patients
| Variables | Total (n = 93,979) | Δ Serum ferritin, ng/mL/quarter | p value | ||||
|---|---|---|---|---|---|---|---|
|
| |||||||
| <−400 (n = 4,503) | −400 to <−100 (n = 13,910) | −100 to <100 (n = 30,354) | 100 to <400 (n = 31,894) | ≥400 (n = 13,318) | |||
| Age, years | 63±15 | 63±15 | 62±15 | 61±15 | 63±15 | 65±14 | <0.001 |
| Female, % | 44 | 48 | 45 | 42 | 43 | 48 | <0.001 |
| Diabetes mellitus, % | 60 | 54 | 57 | 60 | 62 | 62 | <0.001 |
| Race/ethnicity, % | |||||||
| White | 46 | 41 | 43 | 46 | 47 | 45 | <0.001 |
| African-American | 32 | 38 | 35 | 32 | 31 | 31 | <0.001 |
| Hispanic | 15 | 12 | 15 | 15 | 16 | 16 | <0.001 |
| Asian | 3 | 4 | 4 | 3 | 3 | 4 | <0.001 |
| Others | 4 | 4 | 4 | 4 | 4 | 4 | 0.082 |
| Primary insurance, % | |||||||
| Medicare | 54 | 55 | 54 | 53 | 53 | 56 | <0.001 |
| Medicaid | 7 | 8 | 7 | 7 | 7 | 6 | <0.001 |
| Others | 39 | 37 | 38 | 40 | 40 | 38 | <0.001 |
| Initial access type, % | |||||||
| CVC | 74 | 81 | 79 | 74 | 71 | 72 | <0.001 |
| AVF | 15 | 7 | 10 | 15 | 18 | 17 | <0.001 |
| AVG | 4 | 3 | 3 | 4 | 5 | 5 | <0.001 |
| Others | <1 | <1 | <1 | <1 | <1 | <1 | 0.139 |
| Unknown | 6 | 9 | 7 | 6 | 6 | 6 | <0.001 |
| Baseline spKt/V | 1.47±0.32 | 1.51±0.34 | 1.47±0.32 | 1.45±0.32 | 1.47±0.31 | 1.51±0.31 | <0.001 |
| Comorbidities, % | |||||||
| Hypertension | 52 | 50 | 51 | 52 | 52 | 53 | 0.001 |
| Cystic kidney disease | 2 | 2 | 2 | 3 | 3 | 2 | 0.011 |
| Congestive heart failure | 39 | 37 | 39 | 40 | 39 | 36 | <0.001 |
| Atherosclerotic heart disease | 15 | 14 | 14 | 15 | 15 | 16 | <0.001 |
| Other cardiac disease | 15 | 15 | 15 | 15 | 15 | 16 | 0.006 |
| Cerebrovascular disease | 2 | 2 | 2 | 2 | 2 | 2 | 0.123 |
| Chronic obstructive pulmonary disease | 5 | 5 | 5 | 5 | 5 | 5 | 0.849 |
| Liver disease | 1 | 2 | 2 | 1 | 1 | 1 | <0.001 |
| Thyroid disease | 10 | 10 | 10 | 10 | 10 | 11 | <0.001 |
| Dyslipidemia | 26 | 25 | 25 | 26 | 27 | 27 | <0.001 |
| Autoimmune disease | 2 | 3 | 2 | 2 | 2 | 2 | <0.001 |
| Malignancy | 2 | 4 | 2 | 2 | 2 | 3 | <0.001 |
| HIV antibody positive status | <1 | 2 | <1 | <1 | <1 | <1 | <0.001 |
| Substance abuse | <1 | <1 | <1 | <1 | <1 | <1 | 0.417 |
| Alcohol abuse | <1 | <1 | <1 | <1 | <1 | <1 | 0.145 |
| Baseline laboratory measurements | |||||||
| BMI, kg/m2 | 28.2±7.3 | 26.3±6.7 | 27.7±7.2 | 28.8±7.6 | 28.4±7.3 | 27.3±6.9 | <0.001 |
| Albumin, g/dL | 3.5±0.5 | 3.3±0.5 | 3.4±0.5 | 3.5±0.5 | 3.6±0.4 | 3.5±0.4 | <0.001 |
| Creatinine, mg/dL | 5.9±2.4 | 5.9±2.4 | 6.0±2.5 | 6.0±2.4 | 5.9±2.3 | 5.7±2.2 | <0.001 |
| Bicarbonate, mEq/L | 24±3 | 24±3 | 24±3 | 24±3 | 23±3 | 23±3 | 0.001 |
| Blood HGB, g/dL | 11.2±1.2 | 10.5±1.3 | 10.8±1.2 | 11.1±1.2 | 11.4±1.1 | 11.4±1.1 | <0.001 |
| WBC, mm3 | 7.8±2.6 | 8.4±3.3 | 7.9±2.7 | 7.7±2.6 | 7.7±2.6 | 7.8±2.5 | <0.001 |
| Lymphocyte (% of WBC) | 20.9±7.4 | 19.9±8.3 | 20.6±7.6 | 21.0±7.3 | 21.0±7.3 | 20.7±7.5 | <0.001 |
| Platelet, ×109/L | 251±88 | 251±110 | 256±91 | 252±87 | 249±83 | 251±88 | <0.001 |
| iPTH, pg/mL | 317 (201–489) | 267 (155–425) | 306 (190–486) | 330 (210–507) | 323 (209–494) | 304 (194–460) | <0.001 |
| Alkaline phosphatase, μ/L | 87 (69–114) | 95 (74–133) | 89 (70–117) | 86 (68–113) | 86 (68–111) | 88 (69–116) | <0.001 |
| Calcium, mg/dL | 9.1±0.6 | 9.2±0.6 | 9.1±0.6 | 9.1±0.6 | 9.1±0.6 | 9.1±0.6 | <0.001 |
| Phosphorus, mg/dL | 5.0±1.1 | 4.7±1.2 | 4.9±1.2 | 5.0±1.2 | 5.0±1.1 | 4.9±1.1 | <0.001 |
| Ferritin, ng/mL | 276 (160–473) | 1,037 (795–1,404) | 492 (351–696) | 238 (144–381) | 217 (131–349) | 256 (156–418) | <0.001 |
| TIBC, mg/dL | 226±48 | 188±46 | 207±46 | 229±47 | 234±46 | 230±47 | 0.001 |
| ISAT, % | 23±9 | 29±13 | 26±10 | 23±8 | 22±7 | 22±8 | <0.001 |
| nPCR, g/kg/day | 0.80±0.22 | 0.76±0.24 | 0.77±0.22 | 0.79±0.21 | 0.81±0.21 | 0.81±0.22 | <0.001 |
| Iron dose, mg/month | 333 (150–500) | 0 (0–133) | 150 (33–333) | 317 (150–433) | 400 (267–550) | 500 (333–667) | <0.001 |
| ESA dose, U/week | 4,700 (1,512–12,000) | 4,694 (1,540–12,100) | 4,669 (1,530–11,804) | 4,714 (1,500–12,099) | 4,653 (1,500–11,860) | 4,839 (1,584–12,278) | 0.004 |
Continuous values are expressed as mean ± SD if normally distributed or median (interquartile range) if skewed.
AVF, arteriovenous fistula; AVG, arteriovenous graft; BMI, body mass index; CVC, central venous catheter; ESA, erythropoiesis stimulating agent; HGB, hemoglobin; iPTH, intact parathyroid hormone; ISAT, iron saturation; nPCR, normalized protein catabolic rate; spKt/V, single pool Kt/V; TIBC, total iron binding capacity; WBC, white blood cell.