Table 1.

Baseline characteristics of the study population by the median of mean corpuscular volume

VariablesTotal, n=1439MCV<90.8, n=717MCV≥90.8, n=722P Value
Age, yr64.1±12.260.9±13.167.3±10.3<0.001
Age category, yr<0.001
 <50124 (17.3%)51 (7.1%)175 (12.2%)
 50–64258 (36%)179 (24.8%)437 (30.3%)
 ≥65335 (46.7%)492 (68.1%)827 (57.5%)
Sex, % men795 (55.3%)362 (50.5%)433 (59.9%)<0.001
Educational level0.11
 Illiterate309 (21.5%)150 (20.9%)159 (22%)
 Primary school691 (48%)327 (45.6%)364 (50.4%)
 Junior high school153 (10.6%)79 (11.0%)74 (10.3%)
 Senior high school171 (11.9%)98 (13.7%)73 (10.1%)
 Junior college48 (3.3%)30 (4.2%)18 (2.5%)
 University and graduate school67 (4.7%)33 (4.6%)34 (4.7%)
Marital status0.02
 Single61 (4.2%)42 (5.9%)19 (2.6%)
 Married1149 (79.9%)566 (78.9%)583 (80.8%)
 Widowed209 (14.5%)97 (13.5%)112 (15.5%)
 Separated8 (0.6%)4 (0.6%)4 (0.6%)
 Divorced12 (0.8%)8 (1.1%)4(0.6%)
Causes of CKD<0.001
 DM536 (37.2%)316 (44.1%)220 (30.5%)
 Hypertension356 (24.7%)157 (21.9%)199 (27.6%)
 Chronic GN160 (11.1%)74 (10.3%)86 (11.9%)
BMI, kg/m224.9±4.025.3±4.124.5±4.0<0.001
Smoker, %0.47
 Current smoker 294 (20.4%)141 (19.7%)153 (21.2%)
Alcohol, %0.56
 Never1257 (87.4%)633 (88.3%)624 (86.4%)
 Current73 (5.1%)33 (4.6%)40 (5.5%)
 Former109 (7.6%)51 (7.1%)58 (8.0%)
Medication prescription
 ACE inhibitor/ARB910 (63.2%)486 (67.8%)424 (58.7%)<0.001
 Vitamin B12 (cyanocobalamin)295 (20.5)132 (18.4)163 (22.6)0.05
 Iron preparations212 (14.7)128 (17.9)84 (11.6)0.001
 Folic acid358 (24.9)155 (21.6)203 (28.1)0.004
 Erythropoiesis-stimulating agents324 (22.5)176 (24.6)148 (20.5)0.06
 Fibrate75 (5.2)48 (6.7)27 (3.7)0.01
 Statin536 (37.3)298 (41.6)238 (33.0)0.001
Comorbidity
 Cancer140 (9.7%)49 (6.8%)91 (12.6%)<0.001
 Cerebrovascular disease202 (14.0%)112 (15.6%)90 (12.5%)0.09
 Chronic lung disease216 (15.0%)102 (14.2%)114 (15.8%)0.42
 Congestive heart failure147 (10.2%)82 (11.4%)65 (9%)0.14
 Coronary artery disease361 (25.1%)174 (24.3%)187 (25.9%)0.50
 Dementia34 (2.4%)11 (1.5%)23 (3.2%)0.05
 DM672 (46.7%)389 (54.3%)283 (39.2%)<0.001
 Hypertension1004 (69.8%)530 (73.9%)474 (65.7%)0.001
 Liver cirrhosis24 (1.7%)5 (0.7%)19 (2.6%)<0.01
 Peripheral arterial disease19 (1.3%)8 (1.1%)11 (1.5%)0.65
 Autoimmune disease75 (5.2%)36 (5.0%)39 (5.4%)0.81
Laboratory data
 WBC count ×103/L7.1 (5.7–8.8)7.4 (6.0–9.1)6.8 (5.6–8.4)<0.001
 Hemoglobin, g/dl10.4 (9–12)10.1 (8.8–11.7)10.6 (9.2–12.3)0.001
 Platelet count ×103/L218 (177–267)230 (190–279)203 (166–254)<0.001
 Albumin, g/dl3.8 (3.4–4.2)3.7 (3.3–4.2)3.9 (3.6–4.3)<0.001
 MCV, fl90.8 (87.2–95.6)87.17 (84.16–89.1)95.6 (93.83–98)<0.001
 RDW, %14.3 (13.5–15.4)14.5 (13.6–15.6)14.2 (13.5–15.1)<0.001
 BUN, mg/dl42.1 (29–63.3)44.2 (30–65.9)39.6 (28.3–60.8)0.001
 Creatinine, mg/dl2.9 (2.0–5.0)3.0 (2.0–5.2)2.7 (2.0–4.7)0.04
 eGFR, ml/min per 1.73 m219.7 (10.6–30.9)18.4 (10.1–30.3)20.6 (11.0–31.9)0.03
 Ca, mg/dl8.8 (8.4–9.2)8.8 (8.3–9.1)8.9 (8.4–9.2)<0.01
 Phosphate, mg/dl4 (3.4–4.7)4.2 (3.5–5)3.9 (3.3–4.5)<0.001
 Cholesterol, mg/dl180 (153–210)184 (155–217)177 (151–204)<0.01
 Triglyceride, mg/dl130 (92–184)141 (103–203)119 (85–171)<0.001
 GPT, U/L19 (13–31)18 (13–30)19 (13–31)0.28
 Uric acid, mg/dl7.9 (6.7–9)8.1 (6.9–9.3)7.7 (6.5–8.8)<0.001
 24-h Proteinuria, mg684.4 (169.5–2143.7)884.6 (215.4–2855.1)556.8 (117.1–1679.8)<0.001
  • Values are expressed as means±SD, medians (interquartile range), or numbers (percentage). MCV, mean corpuscular volume; BMI, body mass index, ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blocker; DM, diabetes mellitus; WBC, white blood cell; RDW, red cell distribution width; Ca, calcium; GPT, glutamic-pyruvic transaminase.