We included seven studies in which workers were treated with exposure in vivo as the major component of anxiety treatment. Two studies had a high quality of evidence, three studies had a moderate quality of evidence, and two studies had a low quality of evidence. Four studies concerned workers with obsessive-compulsive disorders (OCD), one study concerned a mixed group of workers with OCD or severe phobias, and two studies concerned workers with post-traumatic disorder (PTSD). For OCD we found a low to high quality of evidence that exposure in vivo can reduce adverse work-related outcomes with a medium to large effect in five different modalities and comparisons (Group CBT vs. SSRIs, group CBT plus SSRIs vs. SSRIs, clinician guided CBT vs. systematic self-relaxation, exposure homework combined with Clomipramine vs. Clomipramine with anti-exposure homework). We found moderate evidence that exposure in vivo did not reduce adverse work-related outcomes in workers with OCD in three other modalities and comparisons (computer CBT at home via telephone vs. systematic self-relaxation, exposure at home vs. response prevention, exposure at home plus response prevention vs. response prevention). Moreover, in a meta-analysis of two OCD studies representing the net contribution of exposure in vivo, we found moderate evidence of a medium-sized effect on work-related outcome. Furthermore, we found that this work-related effect was combined with moderate evidence of no increase in anxiety related outcomes. Based on both meta-analyses, we may conclude that there is moderate evidence that anxiety treatments including exposure in vivo can reduce adverse work-related outcomes in workers with OCD with a medium-sized effect, and do not increase anxiety. For workers with PTSD, we found a high quality of evidence that exposure in vivo can reduce adverse work-related outcomes with a medium to large effect in two different modalities and comparisons (prolonged exposure vs. waiting list, prolonged exposure plus cognitive restructuring vs. waiting list). We found a low quality of evidence that exposure in vivo compared with imaginal exposure did not differ in improving work-related outcomes. The work-related effects for workers with PTSD were obtained without increasing anxiety.
That we found only seven relevant studies for this review after a comprehensive and sensitive literature search is a remarkable finding in and of itself. We included four studies involving workers with OCD, one study involving a mixed group of workers with OCD and severe phobias, two studies involving workers with PTSD, and no studies involving workers with other anxiety disorders. These findings are in sharp contrast with the prevalence of studies that have reported an association between a variety of anxiety disorders and work-related outcomes such as absence due to sickness, presenteeism, and decreased productivity. Our findings in workers with OCD are consistent with the low number of studies with work-related results in Steketee's review focussed on OCD and social functioning, which is a broader concept and includes work-related, social, and leisure-related outcomes . Our review had three studies in common with Steketee's review.
Another suprising finding is that only one of the seven included studies investigated an outcome parameter related to return-to-work, i.e., employment status while increased sickness absence is frequently reported in cross-sectional studies [7, 10, 11, 38]. The other studies investigated self-reported work functioning, which is a broader concept than return-to-work. In future studies, return-to-work outcomes should be evaluated more often.
A third noteworthy finding is that no controlled studies have been performed in which exposure in vivo was aimed at specific anxiety-provoking work situations, i.e., situations related to specific tasks, social relations, or workplaces. Avoidance of such tasks, relationships, or workplaces can hinder good job performance. Specific work-related anxiety complaints and anxiety disorders such as work-related panic, work-related phobia, work-related social phobia, and work-related generalised anxiety exist as clinical phenomena partly independent of anxiety disorders in general and therefore deserve specific therapeutic attention .
A strength of this review is its sensitive and comprehensive search of four electronic databases, using search words partly based on prior bibliographic research. Furthermore, we used the GRADE criteria, recommended by the Cochrane Collaboration, to judge the quality of evidence of included studies.
Although the distinction between high and low-risk of bias or high and low quality of evidence of studies is still controversial, it offers the advantage that the process of labelling the risk of bias and the quality of evidence is explicit and transparent .
Usually, blinding of participants and health care providers is one of the criteria for assessing risk-of-bias. We excluded these aspects of the assessment as they lack applicability in this type of intervention study. Workers cannot be blinded adequately to the intervention they receive and health care providers cannot be blinded sufficiently to the intervention they provide [34, 35]. Blinding of assessors is the only criterion that remains to reduce the risk of bias in this type of study.
A weak point of this review is that it is not possible to evaluate the compliance with exposure in vivo because this was not reported in the included studies. Thus, we are uncertain about the minimal dose of exposure in vivo that could have reduced work-related adverse outcome. Furthermore, all the included studies evaluated exposure in vivo in the context of a much broader treatment strategy, rather than by itself. This could have diminished or strengthened the effect of the treatment, as interaction may have occurred between the effects of exposure in vivo and the effects of other components of the intervention strategy.
A methodological consideration of this review is that we calculated SMDs based on the final post-treatment scores, not on the change score. According to the Cochrane Handbook for Systematic Reviews of Interventions, this is an adequate option . We chose to do so because final post-treatment scores were available in five of the seven included studies, so we could compare SMDs between individual studies. In contrast, the change score was only available in one study .
Generalising the results of this review to workers with OCD must be done cautiously, as we found mixed results in different comparisons between groups. The results of this review cannot be generalised to anxiety disorders other than OCD without discussion, as our included studies mainly concerned workers with OCD and we found mixed results of exposure in vivo in two studies that included workers with PTSD.
In future research, priority should be given to high-quality randomised controlled trials (RCTs) applying exposure in vivo to a variety of anxiety disorders, and measuring work-related outcomes as well as anxiety symptoms. In particular, work-related outcomes such as work functioning, productivity, and absence due to sickness should be evaluated. Future research should be aimed at work-related anxiety complaints and disorders, as they can be distinguished from anxiety disorders in general. Reliable and valid work-related outcome measures are needed to evaluate interventions for general anxiety and for work-related anxiety. Recently developed measures, such as the MINI work anxiety interview and the Occupational Functioning Scale, can be considered for use in such research . Exposure in vivo should be compared with other effective treatments for anxiety disorders that are part of usual care such as SSRIs, as these are more stringent control conditions than waiting list or relaxation.