Characteristics of the study population according to anemia and anemia type
| Characteristic . | No anemia . | CKD anemia . | Iron-deficiency anemia . | Anemia of inflammation . | Anemia with B12/folate deficiency . | Anemia unexplained . |
|---|---|---|---|---|---|---|
| Total no. | 496 | 9 | 15 | 21 | 9 | 32 |
| Age, y | 73.3 (69.9-77.9) | 89.0‡ (84.0-90.8) | 72.2 (68.8-90.7) | 78.5‡ (74.7-83.1) | 85.2† (73.6-87.9) | 78.8† (73.8-85.5) |
| Male, % | 46.5 | 44.4 | 73.3 | 61.9 | 33.3 | 27.3 |
| Female, % | 53.5 | 55.6 | 26.7 | 38.1 | 66.7 | 72.7 |
| Years of education | 5.0 (4.0-6.0) | 4.0† (4.0-5.0) | 5.0 (3.0-5.0) | 5.0 (4.0-5.0) | 5.0 (3.0-5.0) | 5.0 (4.0-5.0) |
| Body mass index, % | ||||||
| Less than 25 kg/m2 | 29.6 | 55.6‡ | 26.7 | 57.1‡ | 33.3 | 30.2 |
| More than 25 kg/m2 | 70.4 | 44.4 | 73.3 | 42.9 | 66.7 | 69.7 |
| Hepcidin, ng/mg creatinuria | 60.7 (34.5-114.2) | 64.0 (57.5-81.0) | 15.0‡ (0.0-21.6) | 50.9‡ (17.7-105.5) | 49.4 (38.7-91.1) | 80.0 (42.0-103.4) |
| Hemoglobin, g/dL | 14.0 (13.3-14.8) | 10.4‡ (8.8-11.3) | 11.1‡ (9.9-12.2) | 11.8‡ (11.0-11.9) | 11.9‡ (11.4-12.5) | 11.7‡ (11.4-12.0) |
| Ferritin, mg/L | 118 (61-206) | 108 (62-134) | 8‡ (6-11) | 67† (18-109) | 106 (67-147) | 103 (71-179) |
| Soluble transferrin receptor, nM/L | 16.0 (13.6-19.2) | 19.2 (16.8-28.8) | 28.8‡ (19.2-38.4) | 20.8‡ (17.4-27.2) | 14.4 (13.6-16.0) | 16.0 (14.4-18.4) |
| Iron, μg/dL | 82 (67-99) | 61 (38-68) | 32 (18-41) | 49 (38-55) | 84 (73-95) | 82 (73-97.0) |
| Erythropoietin, mU/mL | 9.7 (7.4-12.5) | 25‡ (19-34) | 27‡ (19-58) | 11.5‡ (9.5-23.4) | 9.7 (8.7-11.0) | 11.5 (9.7-14.2) |
| Vitamin B12, pg/mL | 374 (266-508.0) | 340† (274-1108) | 313 (194-404) | 214‡ (175-376.0) | 309 (157-362) | 453 (318-567) |
| Folate, ng/mL | 3.1 (2.4-4.2) | 3.7 (2.8-6.0) | 3.1 (2.1-4.8) | 2.5 (2.2-4.1) | 1.8‡ (1.7-2.1) | 4.1‡ (3.0-5.3) |
| Creatinine clearance, mL/min | 75.6 (58.6-93.8) | 19.6‡ (13.6-24.1) | 69.1 (42.2-102.7) | 57.8 (45.2-83.6) | 62.9 (48.9-69.5) | 68.6 (47.9-87.4) |
| Presence of an inflammatory condition, %* | 2.4 | 55.5‡ | 13.3 | 42.9‡ | 0.0 | 9.1 |
| Interleukin-6, pg/mL | 0.73 (0.37-1.43) | 3.4‡ (3.4-5.4) | 1.5‡ (0.8-2.6) | 1.8‡ (1.1-2.1) | 1.5† (1.2-2.7) | 1.3† (0.8-2.0) |
| C-reactive protein, mg/L | 1.3 (0.6-2.8) | 9.2‡ (3.2-13.7) | 3.5‡ (1.4-5.2) | 3.6‡ (2.0-9.0) | 2.3 (1.3-2.6) | 1.5 (0.8-3.4) |
| Tumor necrosis factor-α, pg/mL | 1.9 (1.4-3.2) | 5.5‡ (3.3-7.2) | 2.0 (1.7-3.4) | 2.9‡ (1.8-5.2) | 2.5 (1.9-3.0) | 2.5 (1.9-3.6) |
| Interleukin-1β, pg/mL | 0.01 (0.00-0.67) | 0.08 (0.00-7.9) | 0.00 (0.00-6.6) | 0.00 (0.00-0.93) | 0.00 (0.00-0.00) | 0.00 (0.00-0.71) |
| Interleukin-1 receptor antagonist, pg/mL | 130.0 (95.8-185.3) | 193† (158-306) | 136 (89.0-173.0) | 124.7 (87.5-187.2) | 154.1 (86.7-178.3) | 128.0 (89.9-179.3) |
| Interleukin-18, μg/mL | 382 (303-479) | 545 (463-574) | 410 (345-482) | 376.6 (286.4-555) | 343 (255-390.3) | 337 (268-518) |
| Characteristic . | No anemia . | CKD anemia . | Iron-deficiency anemia . | Anemia of inflammation . | Anemia with B12/folate deficiency . | Anemia unexplained . |
|---|---|---|---|---|---|---|
| Total no. | 496 | 9 | 15 | 21 | 9 | 32 |
| Age, y | 73.3 (69.9-77.9) | 89.0‡ (84.0-90.8) | 72.2 (68.8-90.7) | 78.5‡ (74.7-83.1) | 85.2† (73.6-87.9) | 78.8† (73.8-85.5) |
| Male, % | 46.5 | 44.4 | 73.3 | 61.9 | 33.3 | 27.3 |
| Female, % | 53.5 | 55.6 | 26.7 | 38.1 | 66.7 | 72.7 |
| Years of education | 5.0 (4.0-6.0) | 4.0† (4.0-5.0) | 5.0 (3.0-5.0) | 5.0 (4.0-5.0) | 5.0 (3.0-5.0) | 5.0 (4.0-5.0) |
| Body mass index, % | ||||||
| Less than 25 kg/m2 | 29.6 | 55.6‡ | 26.7 | 57.1‡ | 33.3 | 30.2 |
| More than 25 kg/m2 | 70.4 | 44.4 | 73.3 | 42.9 | 66.7 | 69.7 |
| Hepcidin, ng/mg creatinuria | 60.7 (34.5-114.2) | 64.0 (57.5-81.0) | 15.0‡ (0.0-21.6) | 50.9‡ (17.7-105.5) | 49.4 (38.7-91.1) | 80.0 (42.0-103.4) |
| Hemoglobin, g/dL | 14.0 (13.3-14.8) | 10.4‡ (8.8-11.3) | 11.1‡ (9.9-12.2) | 11.8‡ (11.0-11.9) | 11.9‡ (11.4-12.5) | 11.7‡ (11.4-12.0) |
| Ferritin, mg/L | 118 (61-206) | 108 (62-134) | 8‡ (6-11) | 67† (18-109) | 106 (67-147) | 103 (71-179) |
| Soluble transferrin receptor, nM/L | 16.0 (13.6-19.2) | 19.2 (16.8-28.8) | 28.8‡ (19.2-38.4) | 20.8‡ (17.4-27.2) | 14.4 (13.6-16.0) | 16.0 (14.4-18.4) |
| Iron, μg/dL | 82 (67-99) | 61 (38-68) | 32 (18-41) | 49 (38-55) | 84 (73-95) | 82 (73-97.0) |
| Erythropoietin, mU/mL | 9.7 (7.4-12.5) | 25‡ (19-34) | 27‡ (19-58) | 11.5‡ (9.5-23.4) | 9.7 (8.7-11.0) | 11.5 (9.7-14.2) |
| Vitamin B12, pg/mL | 374 (266-508.0) | 340† (274-1108) | 313 (194-404) | 214‡ (175-376.0) | 309 (157-362) | 453 (318-567) |
| Folate, ng/mL | 3.1 (2.4-4.2) | 3.7 (2.8-6.0) | 3.1 (2.1-4.8) | 2.5 (2.2-4.1) | 1.8‡ (1.7-2.1) | 4.1‡ (3.0-5.3) |
| Creatinine clearance, mL/min | 75.6 (58.6-93.8) | 19.6‡ (13.6-24.1) | 69.1 (42.2-102.7) | 57.8 (45.2-83.6) | 62.9 (48.9-69.5) | 68.6 (47.9-87.4) |
| Presence of an inflammatory condition, %* | 2.4 | 55.5‡ | 13.3 | 42.9‡ | 0.0 | 9.1 |
| Interleukin-6, pg/mL | 0.73 (0.37-1.43) | 3.4‡ (3.4-5.4) | 1.5‡ (0.8-2.6) | 1.8‡ (1.1-2.1) | 1.5† (1.2-2.7) | 1.3† (0.8-2.0) |
| C-reactive protein, mg/L | 1.3 (0.6-2.8) | 9.2‡ (3.2-13.7) | 3.5‡ (1.4-5.2) | 3.6‡ (2.0-9.0) | 2.3 (1.3-2.6) | 1.5 (0.8-3.4) |
| Tumor necrosis factor-α, pg/mL | 1.9 (1.4-3.2) | 5.5‡ (3.3-7.2) | 2.0 (1.7-3.4) | 2.9‡ (1.8-5.2) | 2.5 (1.9-3.0) | 2.5 (1.9-3.6) |
| Interleukin-1β, pg/mL | 0.01 (0.00-0.67) | 0.08 (0.00-7.9) | 0.00 (0.00-6.6) | 0.00 (0.00-0.93) | 0.00 (0.00-0.00) | 0.00 (0.00-0.71) |
| Interleukin-1 receptor antagonist, pg/mL | 130.0 (95.8-185.3) | 193† (158-306) | 136 (89.0-173.0) | 124.7 (87.5-187.2) | 154.1 (86.7-178.3) | 128.0 (89.9-179.3) |
| Interleukin-18, μg/mL | 382 (303-479) | 545 (463-574) | 410 (345-482) | 376.6 (286.4-555) | 343 (255-390.3) | 337 (268-518) |
Data are reported as median values and interquartile ranges or percentages.
Anemia was defined as hemoglobin < 12 g/dL in women and < 13 g/dL in men.
CKD indicates chronic kidney disease.
Any of the following: recent or current infection, malignant cancer, rheumatoid arthritis, inflammatory bowel diseases, connective tissue disorders, or skin ulcer.
P < .05 compared with the “no anemia” group, adjusted for age and sex.
P < .01 compared with the “no anemia” group, adjusted for age and sex.