Burdens of mental disorders: the approach of the World Mental Health (WMH) surveys

Introduction The concept of global burden of disease was first publicized in a landmark report commissioned by the World Bank (1993). The measure developed in that report to operationalize the definition of disease burden was designed to assess the gap in the health of a population, taking into account not only mortality but also the non-fatal consequences of injury and disease. This was accomplished by creating a single summary measure that combined the number of years lost due to premature mortality with the number of years “lost” due to living with disabling non-fatal conditions. As a continuation of that work, the World Health Organization (WHO) and Harvard University published the Global Burden of Disease (GBD) study (Murray & López 1996) in an effort to provide systematic estimates of the leading causes of death globally and to combine these estimates with the leading causes of disability. The GBD study took exhaustive measurements of the disability-adjusted life years (DALYs) lost due to more than 100 diseases and 19 risk factors. The first publication of the GBD study estimated that in 1990 unipolar major depression was the fourth leading cause of the loss of DALYs worldwide (3.7%), exceeded only by respiratory infections (8.2%), diarrheal diseases (7.2%), and perinatal conditions (6.7%). Projections estimate that unipolar major depression will be the number one leading cause of total disability worldwide by the year 2030 (World Health Organization 2008). The GBD made it very clear, almost for the first time, that mental disorders are a major challenge to global health. A totally renewed set of GBD estimates for the year 2010, with more conditions and risk factors, was released at the end of 2012 (Murray et al. 2012). A subsequent systematic review of epidemiological studies on mental disorders examined estimates of frequency (one-year prevalence), risk of mortality, and disability associated with 10 mental disorders (Eaton et al. 2007). In that review, the one-year prevalence of major depressive disorders (median of 42 studies) was 5.3% of the adult population, with a median excess risk of mortality of 70% (OR = 1.7) and a disability weighting between 0.35 (0 [worst] to 1 [best]) and a Sheehan Disability Score of 58 (0 [worst] to 100 [best]). Because of their high prevalence and associated significant disability, the review estimated that the cost of mental disorders in Western countries were huge. In Europe, the total cost of mental disorders in 2011 was estimated to be €461 billion (nearly €1,000 per inhabitant) (Gustavsson et al. 2011). Of those, 39% corresponded to direct medical costs (due to the use of professional services, medical interventions, and medication), 13% to other direct non-medical services, and almost half (48%) to indirect costs (those incurred due to sick leave, early retirement, and premature death) (Gustavsson et al. 2011). Affective disorders, and especially unipolar depression, alone accounted for more than half of the indirect costs, indicating the considerable toll such disorders place on European social productivity.