Background: Cognitive behavioral therapy (CBT) and SSRI/SNRI antidepressants have proven to be effective treatments for anxiety and depression. The gain from combined CBT and antidepressant therapy has in some studies been greater than from monotherapy. Benzodiazepines may interfere with the efficacy of individual CBT-treatment. We examined the effects of SSRI/SNRI antidepressants and the effects of benzodiazepines/z-drugs on the efficacy of group CBT (gCBT) in primary care.

Material and methods: Primary outcome measures were the Beck's Depression Inventory II (BDI-II) and the Beck's Anxiety Inventory (BAI) scores before treatment and after the last session. The last observed score was carried forward and compared to the initial score for each individual, irrespective of the timing of the last score (LOCF). Mean change of scores was compared between groups of individuals on or not on SSRI/SNRI antidepressants and/or benzodiazepines/z-drugs.

Results: Over three years 557 subjects participated in a 5 week-long gCBT. Of these 355 returned BDI-II and 350 returned BAI at least twice. The mean score on SSRI/SNRI or benzo/z-drugs fell significantly both for those on combined treatment (medication and gCBT) and those who only received gCBT. Combined treatment with SSRI/SNRI and gCBT led to a greater fall in depressive symptoms compared to gCBT monotherapy. The efficacy of such combined treatment was less for those who also were prescribed benzodiazepines and/or z-drugs.

Conclusions: Group CBT significantly improved symptoms of anxiety and depression in primary care. The improvement was not reduced by concomitant use of SSRI/SNRI antidepressants nor of benzodiazepines/z-hypnotics. The use of such medication is therefore not contraindicated for gCBT participants, at least not short term. Adding SSRIs or SNRIs to gCBT led to greater efficacy in reducing depressive symptom though the efficacy of such combined treatment was less for those who were also prescribed benzodiazepines and/or z-hypnotics.

Figures and tables:

Table I: Average score on BDI-II and BAI and standard deviation before and after group cognitive behavioural therapy

BDI-II	Not on benzos,z-drugs nor SSRIs/SNRIs* (N=176 )		On benzos/z-drugs (N=29)		On SSRIs/SNRIs (N=108)		Benzos/z+SSRIs/SNRIs (N=42)
	M	Sd	M	Sd	M	Sd	M	Sd
Pre treatment	23,43	9,57	18,35	8,66	25,97	10,34	24,87	10,19
Post treatment	17,58	11,92	12,68	8,95	16,27	11,63	20,03	12,16
BAI	Not on benzos, z-drugs nor SSRIs/SNRIs* (N=175 )		On benzos/z-drugs  (N=28)		On SSRIs/SNRIs  (N=106)		Benzos/z+SSRIs/SNRIs  (N=41)
	M	Sd	M	Sd	M	Sd	M	Sd
Pre treatment	18,84	11,49	16,76	8,85	20,74	11,99	22,87	12,39
Post treatment	13,47	10,82	13,37	9,33	13,97	10,01	16,77	13,21

*Not on benzodiazepines, z-hypnotics, SSRIs or SNRIs

Figure 1. BDI-II score before and after treatment among control group and drug groups. 

Figure 2. BAI score before and after treatment among control group and drug groups.

Key words: Group-CBT, transdiagnostic CBT, antidepressants, benzodiazepines, anxiety, depression.

Correspondence: Engilbert Sigurdsson, engilbs@landspitali.is

Eriksson EBS1,2, Kristjansdottir H2,3,4, Sigurdsson JF2,4, Agnarsdottir A2, Sigurdsson E2,4

¹Institute of Psychiatry, King's College University, ²Mental Health Services, Landspítali-The National University Hospital of Iceland., ³Reykjavík University, ⁴Faculty of Medicine, University of Iceland