Global burden of depressive disorders: Issue of duration

The Global Burden of Disease (GBD) study examined the impact of 107 major diseases in a comparative framework including both mortality and disability. When ‘disability’ was taken into account, the formerly unrecognised burden of mental disorders became undeniably evident. Mental disorders ranked as high as cardiovascular and respiratory diseases, surpassing all cancers combined and even HIV infection. Depressive disorders, as a single diagnostic category, were the leading cause of disability worldwide. These results have provided the most powerful scientific support and advocacy for mental health care, because they highlighted loss of human productivity due to mental disorders (Üstün, 1999). From a scientific point of view, the GBD study is a ‘ meta-synthesis’ of epidemiological information concerning incidence, prevalence, duration, severity, associated disability, age of onset, course and treatment rates of major diseases as well as mortality due to these conditions. These epidemiological indicators are built into an internally consistent model of the disease, adjusting for disability (i.e. health levels) throughout the life span. In calculating the burden of disease, ‘ duration’ is a key driver — like the length of mortgage that drives your monthly payments. We therefore need to study duration in terms of onset, length and end of an episode with stopwatch precision, and determine the distribution of each element in the general population. (January 2002)