BMC Public Health 2009, 9:140 http://www.biomedcentral.com/1471-2458/9/140 part of a work-directed intervention programme may be an interesting new approach. During such an exposure in vivo treatment patients can gradually learn to cope more actively with stressful work situations. Exposure in vivo is a well-documented, evidence-based behavioural treatment for anxiety disorders [21], which decreases anxiety symptoms and associated avoidance behaviour [22,23]. Although high quality studies on work-related effects of exposure in vivo in patients with anxiety disorders are scarce [24], the available evidence suggests that exposure in vivo can have neutral or positive work-related effects on patients with obsessive-compul- sive disorder (OCD) and posttraumatic stress disorder (PTSD) [24-30]. Exposure in vivo treatment in only one of these controlled studies [30] can be considered as being work-directed. The effectiveness of this intervention indi- cated a high re-employment rate of PTSD patients, a result that was also found in another non-controlled study with PTSD patients [31]. So, exposure in vivo could be an effec- tive part of a work-directed intervention programme. However, none of these studies reported the effects on sick leave. In order to enhance the return to work of patients on sick leave due to CMDs, we developed a work-directed inter- vention programme based on the principles of exposure in vivo (RTW-E programme). We developed this pro- gramme for application by OPs in addition to their care as usual for patients with CMDs. To evaluate the effective- ness of the programme on sick leave measures, we planned to compare this programme with care as usual. As part of this evaluation, we also planned to compare the effectiveness of the RTW-E programme on sick leave meas- ures between employees with anxiety disorders and employees with other CMDs. We consider this evaluation interesting as exposure in vivo in clinical treatment is an established treatment in reducing anxiety symptoms. In addition, we planned to evaluate the cost-effectiveness of the RTW-E programme compared with care as usual (CAU), from a societal perspective. In the designed study, we therefore hypothesized: - that an RTW-E programme is more effective in reduc- ing the sick leave of employees with CMDs compared with CAU - that an RTW-E programme is more effective in reduc- ing sick leave for employees with anxiety disorders compared with employees with other CMDs - that, from a societal perspective, an RTW-E pro- gramme is cost-effective compared with care as usual. Methods/design To describe the design of the study, all the items of the CONSORT statement [32], aimed at improving the qual- ity of reporting of RCTs, will be discussed. To describe the economic evaluation in this study, we used the guidelines on presenting studies on health economics [33]. Dutch context In the Netherlands, most employees on sick leave due to CMDs visit an occupational physician (OP). Individual employees and their employers have, according to national legislation, a shared responsibility for minimiz- ing health complaints and sick leave. In order to accom- plish this, the employer is obliged to contract an OP who is a medical expert as well as an advisor on sick leave for both the employee and the employer. For the individual employee and his supervisor, an important task of the OP is individual counselling in the case of sick leave in order to support the return to work. In order to structure the individual counselling of patients with CMDs, Dutch OPs have developed and implemented professional practice guidelines [34,35]. A majority of the Dutch OPs have received training in counselling according to these guide- lines. Although compliance with these guidelines can be improved [36], we considered working in accordance with these guidelines as representative of care as usual (CAU) in the Netherlands. Study design The study was designed as a two-armed cluster-rand- omized trial (RCT) with randomization on the level of OPs. OPs from various occupational health services agreed to participate in the study. The OPs in the control group counselled their patients according to CAU and the OPs in the intervention group counselled their patients according to the RTW-E programme. After inclusion and baseline measurement, measurement took place every three months from the first day of sick leave for a period of twelve months. In the intervention group, compliance with the RTW-E programme was monitored during fol- low-up. Sick leave was monitored continuously until full return to work was achieved. Recurrences of sick leave were measured every three months. Patients were blinded to the intervention, as OPs were instructed not to inform patients about the content of their counselling. Blinding OPs to the intervention was not feasible as every OP was trained to apply either the experimental intervention (counselling according to the RTW-E programme) or CAU. Therefore, all the OPs knew which type of intervention they conducted. To prevent contamination between the two groups, the OPs in the control group were neither informed about nor received training in the RTW-E programme. The OPs in the inter- vention group were requested not to disclose the new Page 3 of 11 (page number not for citation purposes)