The Clock Drawing Task reveals executive dysfunction in the dialysis population – an underrecognized and underestimated problem

Figures & data

Figure 1. Qualitative differences in CLOX performance of patient without general cognitive decline.

Figure 2. CLOX1, CLOX2 and pentagon results from a patient’s MMSE with no overall cognitive decline.

Table 1. Demographic characteristics of the study group.

	All patients (n = 58)	CLOX1 ≥ 10* (n = 53)	CLOX1 < 10* (n = 5)	p-Value*
General characteristics
Age, years, mean ± SD;(Q1; Q3)	59.47 ± 14.98 (49; 70.25)	59.30 ± 14.62 (49; 70.5)	61.20 ± 20.32 (43; 78)	0.79^b
Female, n (%)	22 (37.9)	20 (37.7)	2 (40.0)	0.034^c^,**
Years of education, mean ± SD	14.84 ± 3.26	15.13 ± 3.10	11.80 ± 3.77	0.028^a^,**
Dialysis vintage, months ± SD (Q1; Q3)	45.93 ± 48.49 (17.75; 55.75)	45.26 ± 48.92 (18; 50.5)	53.00 ± 48.18 (16.5; 105.5)	0.75^b
Dialysis modality Hemodialysis, n (%) Peritoneal dialysis, n (%)	45 (78) 13 (22)	40 (75.5) 13 (24.5)	5 (100.0) 0 (0.0)	0.21^c0.21^c
Biochemical data (mean ± SD)
Creatinine level (mg/dl)	9.30 ± 2.44	9.30 ± 2.51	9.29 ± 1.55	0.99^a
Creatinine clearance (ml/min/1.73m2) (Q1; Q3)	5.40 ± 1.79 (4; 6)	5.45 ± 1.86 (4; 6)	4.80 ± 0.45 (4.5; 5)	0.44^b
Urea level (mg/dl)	111.22 ± 42.34	112.17 ± 43.27	101.20 ± 32.55	0.58^a
PTH level (pg/ml)	500.95 ± 351.30	519.19 ± 359.29	307.60 ± 171.42	0.20^a
Serum phosphate level (mmol/l) (Q1; Q3)	1.93 ± 0.68 (1.52; 2.21)	1.92 ± 0.71 (1.49; 2.22)	1.98 ± 0.23 (1.77; 2.19)	0.85^b
Glucose level fasting (mg/dl) (Q1; Q3)	113.12 ± 45.79 (83.25; 124)	111.17 ± 45.21 (82.5; 122.5)	133.80 ± 52.17 (83.5; 179.5)	0.30^b
CRP (mg/l) (Q1; Q3)	9.02 ± 14.37 (1.40; 11.45)	9.60 ± 14.89 (1.45; 12.6)	2.88 ± 2.63 (0.80; 5.35)	0.13^b
Serum albumin (g/dl) (Q1; Q3)	3.91 ± 0.42 (3.7; 4.1)	3.91 ± 0.43 (3.7; 4.1)	3.88 ± 0.30 (3.65; 4.15)	0.40^b
Comorbidities, n (%)
KTx before	8 (13.8)	7 (13.2)	1 (20.0)	0.67^c
Smoking	8 (13.8)	6 (11.3)	2 (40.0)	0.14^c
Hypertension	50 (86.2)	46 (86.8)	4 (80.0)	0.67^c
Diabetes mellitus	14 (24.1)	12 (22.6)	2 (40.0)	0.39^c
Ischemic heart disease	18 (31.0)	17 (32.1)	1 (20.0)	0.58^c
Stroke/TIA before	2 (3.4)	2 (3.8)	0 (0.0)	0.66^c

n: number of patients; SD: standard deviation; Q1: Quartile 25.; Q3: Quartile 75.; PTH: parathormone; CRP: C-reactive protein; KTx: kidney transplantation; TIA: transient ischemic attack.

* Compared sub-populations; **p < 0.05; ^aStudent’s t test; ^bU Mann–Whitney test; ^cχ2: Chi-squared.

Table 2. Correlation coefficient between test scores and years of education (Spearman’s rho).

	MMSE	MMSE Mungas correction	CLOX1	CLOX2	Years of education
MMSE		0.63**	0.34**	0.27*	0.09
MMSE Mungas correction	0.63**		0.27*	0.27*	−0.38**
CLOX1	0.34**	0.27*		0.48**	−0.13
CLOX2	0.27*	0.27*	0.48**		0.02
Years of education	0.09	−0.37**	−0.13	0.02

* p < 0.05; **p < 0.1.