Table 3.

Polysomnographic parameters and EDS results for all study groups

ParameterCKD Stage 4 to 5 (n = 89)HD (n = 75)Sleep-SCORE Controls (n = 224)P
TST (minutes)366.3 (298.3, 433.2)313.3 (216.2, 388.2)374 (314.3, 421.1)<0.001
CKD > HDa controls > HDa
Sleep efficiency (%)77.8 (67.3, 85.1)69.8 (59.5, 78.9)79.3 (70.1, 86.3)<0.001
CKD > HDb controls > HDa
Stage 1 (% TST)10.1 (6.2, 15.9)11.6 (6.8, 18.1)8.7 (5.5, 12.5)0.014
Controls > HDb
Stage 2 (% TST)61.2 (53.9, 69.8)57.5 (51, 67)63.5 (56.5, 68.4)0.004
Controls > HDb
Stage 3 and 4 (% TST)5.4 (1.3, 10.9)7.3 (1.3, 18.5)2.5 (0.3, 8)<0.001
CKD > controlsb HD > controlsa
REM (% TST)20.3 (14.5, 26)17.9 (11.2, 22.3)21.8 (17.2, 26.2)<0.001
Controls > HDa
AHI8.8 (3.2, 27.6)18.2 (6.7, 30.2)8.6 (4.3, 16.4)<0.001
HD > CKDc HD > controlsa
AHI ≥ 3020 (22.5%)19 (25.7%)25 (11.5%)0.002
CKD > controlsb HD > controlsb
Arousal index8.9 (5.4, 13.4)8.8 (3.9, 15.5)8.5 (5.4, 13.9)0.94
Type of apnea
    obstructive apnea index6.2 (2, 17.3)11.3 (4.1, 23)6 (2.6, 13.2)0.006
HD > controlsb HD > CKDc
    central apnea index<0 (0, 0.3)0.2 (0, 0.7)<0 (0, 0.2)0.001
HD > controlsa HD > CKDc
    mixed apnea index<0 (0, 0.2)<0 (0, 0.3)<0 (0, 0.2)0.34
    nocturnal hypoxemia ≥ 3% TST28 (37.8%)39 (54.9%)49 (27.1%)<0.001
HD > controlsa HD > CKDc
Self-reported sleep
    ESS ≥ 1024 (29.3%)28 (40.6%)74 (33.0%)0.33
  • Results are presented as medians and interquartile ranges or as percentages. Numbers in parentheses reflect the 25th and the 75th percentile of the variables. REM, rapid eye movement; sleep efficiency, percentage of TST as a proportion of the total study duration; AHI ≥ 30, percentage of subjects who had at least 30 apneas/hypopneas during TST; obstructive apnea index, number of obstructive apneas per hour of TST; central apnea index, number of central apneas per hour of TST; mixed apnea index, number of obstructive and central apneas per hour of TST; nocturnal hypoxemia ≥ 3% TST, percentage of subjects who had at least 3% of TST with oxyhemoglobin saturation <90%.

  • a P < 0.001;

  • b P < 0.01;

  • c P < 0.05 for the pairwise comparisons.