Plasma oxytocin changes and anti-obsessive response during serotonin reuptake inhibitor treatment: a placebo controlled study

Table 3 Plasma oxytocin in OCD patients: temporal changes according to response category and treatment

	Total sample	SRI responders n = 16	SRI Non-responders n = 11	Placebo responder n = 1	Placebo Non-responders n = 8	MW: Z, p^a	MW: Z, p^b	MW: Z, p^c
Oxytocin baseline, n = 36	31.3 (22.7, 39.5)	36.0 (25.8, 39.9)	24.5 (19.7, 33.7)	31.2	29.6 (22.3, 39.6)	1.44, 0.15	1.55, 0.12	-0.45, 0.65
Oxytocin week 1, n = 35	31.2 (22.8, 43.8)	30.9 (21.1, 42.6)	30.4 (23.5, 37.4)	-	36.1 (25.1, 47.3)	-0.78, 0.44	-0.47, 0.64	-0.37, 0.71
Oxytocin week 4, n = 33	36.7 (27.0, 43.6)	40.1 (30.0, 53.8)	29.4 (23.7, 35.6)	43.6	35.3 (24.1, 42.3)	2.31, 0.021	2.14, 0.032	-0.68, 0.49
Change from baseline to week 4 (OT-4 – OT-0) n = 33	0.8 (-3.0, 5.6)	1.4 (-6.5, 11.5)	2.4 (-1.3, 4.9)	12.4	-1.9 (-2.7, 2.6)	0.52, 0.60	0.0, 1.0	0.58, 0.56
First week change (OT-1 – OT-0) n = 35	2.8 (-3.8, 5.2)	-5.7 (-13.2, 6.8)	3.7 (2.2, 5.0)	-	2.4 (0.0, 4.8)	-1.36, 0.17	-1.09, 0.28	0.87, 0.39
Change from week 1 to week 4 (OT-4 – OT-1) n = 32	1.8 (-6.8, 11.4)	8.5 (-2.9, 17.5)	-0.8 (-5.9, 2.8)	-	-4.7 (-7.5, 3.3)	2.24, 0.025	1.99, 0.047	0.26, 0.79
OT range, n = 36	10.1 (5.5, 16.4)	15.7 (11.8, 25.0)	5.0 (3.7, 9.7)	12.4	6.8 (4.5, 17.5)	3.61, 0.0003	3.38, 0.0007	0.54, 0.59

Numbers are medians (1^st and 3^rd quartiles). Bolded numbers and texts indicate significant findings. Plasma oxytocin is reported as pg/ml. For response criteria, see Methods.
a: comparison between all responders and all non-responders.
b: comparison between SRI responders and SRI non-responders.
c: comparison between non-responders to SRI and non-responders to placebo.
Only one patient responded to placebo and, hence, is only included in the first (a) statistical analysis. In comparisons between all SRI treated and all placebo treated patients, no significant differences appeared for any of the oxytocin measures.
MW = Mann Whitney statistics; OCD = obsessive-compulsive disorder; OT = plasma oxytocin; OT-0 = baseline sample; OT-1 = week 1 sample; OT-4 = week 4 sample; OT range = intra-individual range between the maximal and the minimal of each patient’s 3 (n = 32) or 2 (n = 4) OT samples; SRI = serotonin reuptake inhibitor.

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