Large contribution of depression to total burden of disease

The Global Burden of Diseases Study of WHO calculated that depression is the leading cause of disability among all major illnesses. Their results indicated that depression is the fourth leading contributor to the total world burden of disease in 2000, accounting for 4.4% of disability-adjusted life years (DALYs). In Europe, depression is the third leading contributor to the total burden of disease, measured in DALYs. The large contribution of depression to the burden of disease is a result of a combination of a high prevalence, high impact on functioning and early age of onset (Üstün et al., 2004). Future projections for global DALYs in the year 2020 show a significant increase in the impact of non-communicable diseases worldwide. As a consequence, depression is expected to reach the second place on the WHO DALYs ranking list in 2020 (Murray & Lopez, 1996).

Depression restricts daily functioning, especially if there is comorbidity

Depressed individuals commonly report poor functioning at work as well as relationship difficulties. The more severe the symptoms of depression are, the more the psychosocial problems worsen. Similarly, when the depression subsides, the affected person’s psychosocial functioning, work performance and relationships return to normal levels (Judd, 2000).

Depression is frequently associated with other psychiatric conditions. Disability increases and quality of life decreases with such comorbidity; the more mental disorders a person has, the more likely he will be disabled by these conditions and experience a low quality of life. People suffering from depression in combination with an anxiety disorder experience a very high rate of functional disability. This has been shown to lead to a substantial demand on healthcare resources (Tylee, 2000).

Economic consequences mainly due to sickness absence

Depression has major economic consequences similar to that of physical illnesses (Smit et al., 2006). Patients with depressive disorder make more use of health care services than patients without this disorder (Bijl & Ravelli, 2000b, Koopmans et al., 2005), and they also often take sickness leave from work. For example, almost 10% of the days of sickness absence taken in Germany in 2004 were recorded as being due to a mental disorder diagnosis, mostly depression (IGES, 2005). The number of sickness days taken for depression in Germany increased by 40 % from the year 2000 to 2004, while decreasing days of sickness was the general trend. This increase affected particularly men and women below the age of 30. Similar trends are reported from some other European countries, although no cross-country comparable data are available (Hensing et al., 2006; Savikko et al., 2001). The high level of sickness absence in depressed people generates high costs in the employment sector. The ESEMeD study demonstrated a strong impact of mental disorder on absenteeism from work in the general population (Alonso et al., 2004). Generally, production losses are estimated to account for 85% of the total costs of mental disorders, with an average of 2,725 euro per person per year in the Netherlands. Of the distinct mental disorders, dysthymia generates the highest costs (Smit et al., 2006).

See also Average length of stay, Mood disorder.