Table 1.
Baseline characteristics stratified by baseline serum ferritin in 81 684 incident hemodialysis patients
| Characteristics | Total (n = 81 684) | Baseline serum ferritin |
P-value | |||
|---|---|---|---|---|---|---|
| <200 (n = 29 067) | 200–<500 (n = 35 012) | 500–<800 (n = 11 158) | ≥800 (n = 6447) | |||
| Age (years) | 62 ± 15 | 60 ± 15 | 63 ± 15 | 64 ± 14 | 64 ± 15 | <0.001 |
| Female (%) | 44 | 42 | 43 | 46 | 49 | <0.001 |
| Diabetes mellitus (%) | 63 | 65 | 64 | 62 | 56 | <0.001 |
| Race/ethnicity (%) | ||||||
| White | 44 | 45 | 44 | 42 | 40 | <0.001 |
| African American | 33 | 31 | 33 | 35 | 39 | <0.001 |
| Hispanic | 16 | 18 | 16 | 14 | 12 | <0.001 |
| Asian | 3.4 | 2.5 | 3.4 | 4.5 | 5.4 | <0.001 |
| Others | 3.8 | 3.7 | 3.8 | 4 | 4.3 | 0.069 |
| Primary insurance (%) | ||||||
| Medicare | 53 | 52 | 53 | 55 | 57 | <0.001 |
| Medicaid | 7.2 | 7.8 | 6.9 | 7 | 7 | <0.001 |
| Others | 40 | 41 | 40 | 38 | 36 | <0.001 |
| Access type (%) | ||||||
| CVC | 73 | 70 | 74 | 76 | 79 | <0.001 |
| AVF | 16 | 20 | 15 | 12 | 9 | <0.001 |
| AVG | 4.4 | 4.5 | 4.5 | 4.3 | 3.7 | 0.003 |
| Others | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.689 |
| Unknown | 6.6 | 6.5 | 6 | 7.2 | 8.8 | <0.001 |
| KRU (mL/min) | 3.44 (1.93–5.56) | 3.84 (2.23–6.06) | 3.42 (1.95–5.47) | 2.98 (1.58–5.04) | 2.70 (1.34–4.53) | <0.001 |
| spKt/V | 1.47 ± 0.32 | 1.44 ± 0.32 | 1.47 ± 0.31 | 1.51 ± 0.32 | 1.52 ± 0.33 | <0.001 |
| Comorbidities (%) | ||||||
| Hypertension | 52 | 53 | 53 | 51 | 49 | <0.001 |
| Cystic kidney disease | 2.5 | 2.9 | 2.4 | 1.9 | 1.6 | <0.001 |
| CHF | 42 | 43 | 41 | 39 | 39 | <0.001 |
| ASHD | 16 | 16 | 16 | 15 | 14 | 0.036 |
| Other cardiac disease | 16 | 16 | 16 | 16 | 16 | 0.294 |
| CVD | 1.8 | 1.7 | 1.9 | 1.8 | 1.7 | 0.158 |
| COPD | 5.1 | 5 | 5 | 5.3 | 5.4 | 0.387 |
| Liver disease | 1.4 | 1.3 | 1.4 | 1.5 | 2 | <0.001 |
| Thyroid disease | 11 | 11 | 10 | 11 | 10 | 0.032 |
| Dyslipidemia | 28 | 28 | 28 | 27 | 26 | 0.001 |
| Autoimmune disease | 2 | 1.6 | 1.9 | 2.4 | 3.6 | <0.001 |
| Malignancy | 2.1 | 1.6 | 2 | 2.2 | 4 | <0.001 |
| HIV | 0.5 | 0.3 | 0.5 | 0.7 | 1.2 | <0.001 |
| Substance abuse | 0.3 | 0.3 | 0.3 | 0.2 | 0.3 | 0.824 |
| Alcohol abuse | 0.2 | 0.2 | 0.2 | 0.3 | 0.3 | 0.032 |
| BMI (kg/m2) | 28.1 ± 7.3 | 29.0 ± 7.5 | 28.3 ± 7.3 | 27.2 ± 6.8 | 26.3 ± 6.7 | <0.001 |
| Serum Alb (g/dL) | 3.53 ± 0.46 | 3.60 ± 0.43 | 3.54 ± 0.45 | 3.45 ± 0.48 | 3.32 ± 0.52 | <0.001 |
| Serum Cr (mg/dL) | 6.02 ± 2.36 | 6.07 ± 2.30 | 6.06 ± 2.40 | 5.89 ± 2.38 | 5.80 ± 2.37 | <0.001 |
| Bicarbonate (mEq/L) | 23.48 ± 2.67 | 23.32 ± 2.67 | 23.52 ± 2.63 | 23.65 ± 2.69 | 23.67 ± 2.76 | <0.001 |
| Hb (g/dL) | 11.24 ± 1.15 | 11.35 ± 1.10 | 11.31 ± 1.11 | 11.09 ± 1.18 | 10.67 ± 1.32 | <0.001 |
| WBC (mm3) | 7.74 ± 2.54 | 7.56 ± 2.51 | 7.73 ± 2.41 | 7.99 ± 2.65 | 8.20 ± 3.06 | <0.001 |
| Lymphocyte (% of WBC) | 21.03 ± 7.36 | 21.46 ± 7.18 | 21.08 ± 7.28 | 20.35 ± 7.44 | 19.96 ± 8.15 | <0.001 |
| Platelet (×109/L) | 251.68 ± 85.90 | 253.88 ± 83.59 | 250.97 ± 82.68 | 252.18 ± 85.56 | 247.74 ± 106.53 | <0.001 |
| iPTH (pg/mL) | 322 (206–494) | 341 (223–522) | 323 (208–493) | 298 (188–456) | 272 (160–434) | <0.001 |
| ALP (µ/L) | 87 (69–113) | 85 (68–110) | 86 (69–113) | 87 (70–118) | 94 (72–128) | <0.001 |
| Calcium (mg/dL) | 9.09 ± 0.56 | 9.07 ± 0.56 | 9.09 ± 0.55 | 9.12 ± 0.56 | 9.15 ± 0.60 | <0.001 |
| Phosphorus (mg/dL) | 4.99 ± 1.14 | 5.14 ± 1.14 | 4.98 ± 1.13 | 4.81 ± 1.11 | 4.67 ± 1.13 | <0.001 |
| Ferritin (ng/mL) | 268 (156–458) | 126 (86–163) | 309 (249–388) | 611 (550–689) | 1035 (895–1312) | <0.001 |
| TIBC (mg/dL) | 226.81 ± 47.36 | 247.59 ± 44.34 | 223.03 ± 42.77 | 206.08 ± 44.02 | 189.61 ± 45.99 | <0.001 |
| ISAT (%) | 22.91 ± 8.50 | 20.68 ± 7.07 | 23.08 ± 7.47 | 24.59 ± 8.85 | 29.12 ± 13.67 | <0.001 |
| nPCR (g/kg/day) | 0.80 ± 0.21 | 0.81 ± 0.21 | 0.81 ± 0.21 | 0.80 ± 0.22 | 0.77 ± 0.24 | <0.001 |
| ESA dose (U/week)a | 0 (−3274–7471) | 115 (−3252–7837) | −1 (−3273–7287) | −123 (−3325–7239) | −163 (−3346–7287) | 0.016 |
| Iron dose (mg/month)b | 0 (−183–317) | +34 (−100–200) | 0 (−150–167) | −66 (−258–100) | −300 (−333 to −33) | <0.001 |
| Iron use (%) | 89 | 94 | 93 | 86 | 56 | <0.001 |
Continuous values are expressed as mean ± SD if normally distributed or median (interquartile range) if skewed.
CVC, central venous catheter; AVF, arteriovenous fistula; AVG, arteriovenous graft; KRU, kidney residual urine; spKt/V, single-pool Kt/V; CHF, congestive heart failure; ASHD, atherosclerotic heart disease; CVD, cerebrovascular disease; COPD, chronic obstructive pulmonary disease; BMI, body mass index; Alb, albumin; Hb, hemoglobin; WBC, white blood cell; iPTH, intact parathyroid hormone; ALP, alkaline phosphatase; TIBC, total iron binding capacity; ISAT, iron saturation; nPCR, normalized protein catabolic rate; ESA, erythropoietin-stimulating agent.
aDenotes the ESA dose relative to the median dose of the overall cohort.
bDenotes the iron dose relative to the median dose of the overall cohort.