[Psychological Stress and its Consequences for the Cost of Illness: a Longitudinal Study in Germany].

Objective: The aim of this study was to examine the effects of mental illness on the level and composition of medical costs (outpatient costs, hospital costs, rehabilitation costs, drug costs) over time.

Method: In a longitudinal design, we examined the psychological distress of 3,287 study participants from the adult general population using the Hospital Anxiety and Depression Scale (HADS) and its effect on the level and composition of medical costs resulting from mental illness in the year of survey t0 and the two subsequent years [t1] {t2}.

Results: Compared to the reference group with no mental distress, the cost of illness was significantly increased by a factor of 2.0 [2.2] {1.5} in the low mental distress group, by a factor of 3.7 [4.2] {3.1} in those with moderate mental distress, and by a factor of 7.5 [9.0] {5.2} in those with severe mental distress. Over time, significant effects on illness costs appeared only at the two outer edges of psychological distress levels (no and severe distress levels). As the level of mental distress increased, hospital costs dominated total costs due to mental distress and the proportion of outpatient medical costs in total costs decreased.

Conclusions: The costs of illness rise steeply with the degree of mental stress. Preventing the progression of mental illness is therefore important not only from an individual but also from a health economic perspective.