Within-Subject Reliability and between-Subject Variability of Oxidative Stress Markers in Saliva of Healthy Subjects: A Longitudinal Pilot Study

Table 1

Within-subject test-retest reliability data.

	Morning						Afternoon
	Sampling day mean values			Mean (SD)	ICC	Between-day CV (%)	Sampling day mean values			Mean (SD)	ICC	Between-day CV (%)
	1	2	3		r (95% CI)		1	2	3		r (95% CI)
GPX (U/g)	112.3	119.1	112.9	114.8 (3.8)	0.86 (0.66–0.95)	3.28	154.4	143.7	156	151.4 (6.7)	0.61 (0.06–0.85)	4.40
SOD (U/g)	2801	2725.5	2959.6	2828.7 (119.5)	0.76 (0.39–0.91)	4.22	2636.3	2399.6	2793.6	2609.9 (198.3)	0.77 (0.46–0.91)	7.60
TAC (mmol/g)	1.6	1.7	1.6	1.6 (0.1)	0.76 (0.43–0.91)	4.06	2.2	2	2.2	2.1 (0.1)	0.81 (0.55–0.93)	6.83
UA (umol/g)	323.1	346.1	350.9	340 (14.9)	0.72 (0.32–0.89)	4.38	422.8	414	440.6	425.8 (13.6)	0.51 (0.15–0.82)	3.19
8-OHdG (ug/g)	2.6	2.3	2.3	2.4 (0.2)	0.82 (0.57–0.93)	6.68	2.2	2.4	1.8	2.1 (0.3)	0.83 (0.59–0.94)	14.5
MDA (nmol/g)	665.9	534.1	393.1	531 (136.4)	0.34 (−0.6–0.76)	25.69	1523.9	1142.8	1057.2	1241.3 (248.5)	0.86 (0.66–0.95)	20.01

GPX: glutathione peroxidase; SOD: superoxide dismutase; TAC: total antioxidant capacity; UA: uric acid; 8-OHdG: 8-hydroxydeoxyguanosine; MDA: malondialdehyde; SD: standard deviation; ICC: intraclass correlation coefficient; CI: confidence interval; CV: coefficient of variation. Log transformation required before ICC calculation, due to nonnormal distribution.