Dominique Hange, Nashmil Ariai, Marie Kivi, Maria CM Eriksson, Shabnam Nejati, Eva-Lisa Petersson

The aim of this randomized controlled trial (RCT) was to investigate the effects of internet-based cognitive behavior therapy (ICBT) treatment for depression compared to treatment-as-usual (TAU) on improving work ability and quality of life in patients with mild-to-moderate depression. We also examined whether patients treated with ICBT returned to work more rapidly, that is, had fewer days of sick leave, than patients treated with TAU. This study is based on material from the PRIM-NET RCT that took place between 2010 and 2013. Primary care centers in Region Vastra Gotaland, Sweden, population about 1.6 million. A total of 77 patients with depression randomized to either ICBT (46 patients) or TAU (31 patients). Mean age of participants was 35.8 years, and 67.5% were women. Work ability was measured with the Work Ability Index, depressive symptoms with Montgomery Asberg Depression Rating Scale - self-rating version (MADRS-S), quality of life with EuroQoL-5D (EQ-5D), and number of sick leave days. Both groups showed an association between improved work ability and reduction of depressive symptoms and between improved work ability and better quality of life. ICBT could not be shown to improve work ability more than TAU among patients with mild-to-moderate depression. There were no differences between the groups concerning number of patients with sick leave or number of sick leave days. Our study indicates that a high level of work ability has an association with high health-related quality of life in patients with mild-to-moderate depression, whether they are treated with ICBT or TAU. ICBT has previously been found to be cost-effective and can be seen as a good alternative to TAU. In addition to the ICBT, an intervention oriented toward the work place might improve work ability and reduce the number of sick leave days among patients with depression.