Table 1.

Baseline characteristics of the study cohort stratified by the presence or absence of RLS

CharacteristicAll Participants (n = 235)Absence of RLS (n = 141)Presence of RLS (n = 94)P
Age, years52 ± 1552 ± 1653 ± 140.7
Men150 (65)85 (62)65 (70)0.2
Race0.002
    white153 (66)84 (61)69 (74)
    black70 (30)52 (38)18 (19)
    other8 (4)2 (1)6 (7)
Prior renal replacement therapy0.04
    hemodialysis206 (90)127 (93)79 (85)
    peritoneal dialysis7 (3)3 (2)4 (4)
    kidney transplant5 (2)4 (3)1 (1)
    new to dialysis12 (5)3 (2)9 (10)
Duration of dialysis, years3.6 ± 4.13.5 ± 3.73.8 ± 4.60.7
Estimated dry weight, kg86 ± 2385 ± 2387 ± 240.6
Body mass index, kg/m229 ± 729 ± 829 ± 70.9
Residual urine volume, ml/day387 ± 631360 ± 607425 ± 6670.5
Vascular access type, %0.05
    arteriovenous fistula128 (55)68 (49)60 (64)
    arteriovenous graft37 (16)27 (20)10 (11)
    central venous catheter66 (29)43 (31)23 (25)
Home hemodialysis training time, days27 ± 3824 ± 1231 ± 570.2
Comorbid conditions
    hypertension203 (86)120 (85)83 (88)0.5
    diabetes mellitus100 (43)55 (39)45 (48)0.2
    congestive heart failure58 (25)34 (24)24 (26)0.8
    other cardiovascular disease55 (23)30 (21)25 (27)0.3
    cerebrovascular disease22 (9)14 (10)8 (9)0.7
    atherosclerotic heart disease44 (19)27 (19)17 (18)0.8
    peripheral vascular disease26 (11)17 (12)9 (10)0.6
    chronic obstructive lung disease16 (7)8 (6)8 (9)0.4
    cancer26 (11)14 (10)12 (13)0.5
Current smoker29 (12)14 (10)15 (16)0.2
Assistance with daily activities10 (4)4 (3)6 (6)0.2
Inability to ambulate7 (3)6 (4)1 (1)0.2
Selected prescribed medications
    pramipexole/ropinirole7 (3)1 (1)6 (7)0.02
    anxiolytics/muscle relaxants43 (19)21 (15)22 (24)0.09
    hypnotics/sleep medications35 (15)20 (15)15 (17)0.7
    carbidopa-levodopa3 (1)0 (0)3 (3)0.06
    gabapentin/pregabalin34 (15)15 (11)19 (21)0.06
Selected laboratory values
    hemoglobin, g/dl11.7 ± 1.311.8 ± 1.211.6 ± 1.40.3
    serum ferritin, ng/ml517 ± 313537 ± 349490 ± 2530.3
    transferrin saturation, %29 ± 1229 ± 1128 ± 130.6
    serum calcium, mg/dl8.9 ± 0.78.9 ± 0.68.9 ± 0.80.4
    serum phosphorus, mg/dl5.5 ± 1.45.3 ± 1.35.9 ± 1.50.002
    serum calcium-phosphorus product, mg2/dl252 ± 1350 ± 1256 ± 140.001
    serum intact parathyroid hormone, pg/ml465 ± 422473 ± 449453 ± 3830.8
    serum urea nitrogen, mg/dl58 ± 1757 ± 1660 ± 180.2
    serum creatinine, mg/dl9.2 ± 3.99.1 ± 4.29.3 ± 3.40.7
    serum albumin, g/dl3.8 ± 0.53.8 ± 0.53.8 ± 0.50.9
    serum potassium, mEq/L4.8 ± 0.64.8 ± 0.64.9 ± 0.70.1
  • The data are presented as means ± standard deviation or numbers (percentages). The P values were calculated using unpaired t test or chi-squared test.