Metacognitive Therapy and Work Interventions for Patients on Sick Leave Due to Common Mental Disorders: A Randomized Waiting List Controlled Trial

Common mental health disorders (CMD) such as anxiety and depression are leading contributors to the global burden of disease , generating substantial costs for societies in reduced productivity and increased benefit pay outs. In 2010, the worldwide cost of mental health disability was estimated at US$2.5-8.5 trillion in lost output, and the sum is projected to double by 2030 unless effective policy measures are implemented. For middle- and high-income countries, 30-50 % of disability applications stem from mental health issues, and the proportion is likely greater among the younger part of the work force. In Europe, depression is responsible for 13.7 % of all years lived with disability, and anxiety disorders likely have similar impact. Mental health issues are among the leading causes of disability and early retirement across the European region.

For affected individuals, anxiety and depression reduces quality of life, decreases functioning and increases the risk of further health problems. Sick leave is often used for adults with CMD, but may not always be helpful. Avoidance and isolation are behavioural strategies that maintain anxiety and depression. Absenteeism from work, an important social arena, may strengthen this behaviour, impeding recovery. Even when controlling for the impact of ill health, short term sick leave may in itself increase the risk of future long term absence. In addition, employment rates are 10-15% lower for people with mental ill health than the rest of the population. Exclusion from the work force is in turn associated with poorer mental health, and can heighten the risk of futures depression and even suicide. The relationship between CMD and reduced work-participation is therefore likely bidirectional, and sick leave may not work as intended despite its high cost for society.

The individual and societal burden from sick leave and mental health represents a key policy challenge on the global agenda and the need for efficient measures is urgent. Norway exemplifies this urgent need as expenditure on disability and sickness absence totals 5 % of GDP, by far the highest in the OECD. Efforts have been made to address the issue through several policy initiatives, such as the nationwide Faster Return to Work (FRW) program. The program facilitates buying treatment from different actors to reduce waiting times and thus potentially the duration of sick leave. The impact of the program is uncertain, as little research has been done on its efficacy. Scientific data on Norwegian sick leave follow up is mostly absent. Despite the magnitude of the challenge, there is a clear knowledge gap.

Investment in sick leave follow up has not been equally distributed amongst patient groups. Sixty per cent of all working days lost to disability or sick leave are due to mental health issues and musculoskeletal complaints. Sick leave due to CMD is growing. When caused by mental health issues, disability pension is awarded on average nine years earlier than for somatic reasons, resulting in more working years lost to disability. Though prevalent in the statistics, few CMD patients on sick leave receive treatment. Only 1.4 % of employees on sick leave are referred to specialized mental health treatment. As many as one in three people awarded disability pension for mental illness have never received any form of treatment prior to disability being granted. This shows a severe under-referral and under-treatment for this patient group despite being responsible for the majority of sick leave and disability costs.

A more targeted approach, integrating work-focused interventions with effective CMD treatment is needed for this patient group. Two recent studies have examined such an approach. In the Netherlands, Lagerveld and Blonk conducted a randomized controlled trial where 168 patients on sick leave due to CMD received either cognitive behavioural therapy (CBT), or CBT with an integrated work-focused intervention. Their results showed a 20 % decrease in sickness absence for patients receiving the work-focused intervention, while maintaining effective symptom reduction. In Germany, similar results were found with a smaller sample size. A multicentre trial in Norway looked at registry data for 1193 CMD patients receiving a variation of work-specific interventions, showing a clear reduction in sick leave and disability. Integrated work-focused treatment for CMD is thus a promising avenue of research.