Sleep quality and its correlates in patients with chronic kidney disease: a cross-sectional design

Figures & data

Table 1. Baseline characteristics of the participants divided by sleep quality.

Variable	PSQI global score > 5	PSQI global score ≤ 5	p Value
Age; mean (SD)	63.2 (14.9)	62.3 (14.2)	0.6
Gender (female); n (%)	65 (55%)	60 (32%)	0.0001
BMI (kg/m^2) mean (SD)	29.7 (7.2)	29.8 (5.8)	0.9
Diabetes positive; n (%)	57 (48%)	84 (45%)	0.5
SBP mmHg mean (SD)	139 (24)	139 (19)	0.81
DBP mmHg mean (SD)	67 (15)	67 (13)	0.71
MAP mmHg; mean (SD)	91.2 (15.3)	91.4 (12.1)	0.6
PP mmHg; mean (SD)	71.7 (23.7)	72.8 (20)	0.7
Hb g/L; mean (SD)	119.2 (18)	122 (19)	0.2
Ca; mean (SD)	2.2 (0.2)	2.2 (0.17)	0.7
P; mean (SD)	1.5 (0.5)	1.3 (0.4)	0.02
PTH; mean (SD)	392 (106–500)	342 (97–376)	0.10
Glucose; mean (SD)	7.4 (4)	7.8 (5.8)	0.48
eGFR mL/min/1.73 m^2; mean (SD)	25 (6–43)	25 (10–39)	0.3
BDI; mean (SD)	7.1 (6.9)	3.9 (3.4)	0.0001
PCS; mean (SD)	40.9 (10.1)	43.1 (10.8)	0.07
MCS; mean (SD)	50.1 (10.3)	55.5 (7.6)	0.0001^a

Abbreviations: BQ: Berlin Questionnaire; BDI: Beck Depression Inventory; BDI-FS: the Beck Depression Inventory Fast Screening; BMI: body mass index; Ca: calcium; CKD: chronic kidney disease; eGFR: estimated glomerular filtration rate; Hb: hemoglobin; MAP: mean arterial pressure; MCS: mental component summary scores; PP: pulse pressure; PCS: Physical Component Summary; PSQI: the Pittsburgh Sleep Quality Index.

^aMann–Whitney U test.

Figure 1. Box plot indicating PCS scores and PSQI; abbreviations: PCS: physical component summary, PSQI categorised: The Pittsburgh Sleep Quality Index categorised by the total score.

Figure 2. Box plot indicating MCS scores and PSQI; abbreviations: MCS: mental component summary scores, PSQI categorised: The Pittsburgh Sleep Quality Index categorised by the total score.

Table 2. Variables associated with sleep quality.

Variable	Effect estimate OR^a (95% CI); p	Effect estimate OR^a (95% CI); p	Effect estimate OR^b (95% CI); p
Gender^c	0.36 (0.18–0.72); 0.004	0.42 (0.24–0.7); 0.001	0.42 (0.25–0.69); 0.0006
Ca	5.7 (0.9–37); 0.06	1.72 (0.43–6.9); 0.43	NA
MCS Category (1)^d Category (2)^e Category (3)^f	0.93 (0.91–0.96); 0.002	0.87 (0.43–1.7); 0.6 0.52 (0.25–1.05); 0.07 0.27 (0.12–0.57); 0.007	0.87 (0.44–1.68); 0.87 0.47 (0.24–0.42); 0.02 0.25 (0.11–0.51); 0.002

Abbreviations: BDI: Beck Depression Inventory; MCS: mental component summary scores; OR: odds ratio; CI: confidence interval.

^aContains only variables that were significant in the univariate model.

^bContains only variables that were significant in the multivariate model.

^cMale gender.

^dComparison of less than 25% percentile with 25–50% percentile categories.

^eComparison of 25–50% percentile with 50–75% percentile categories.

^fComparison of 50–75% percentile with more than 75% percentile categories.