An epidemiological approach to depression prevention in old age.

Objective: To identify target groups for prevention of chronic or recurrent depression
in old age such that prevention is likely to become cost-effective. Methods: Data were
used from a population-based cohort study (N = 2,200). Chronic or recurrent
depression was defined when people presented with clinically high levels of depression
at two time points separated by 3 years. Risk profiles of these conditions were
identified using classification and regression trees analysis. The combinations of risk
factors were then evaluated in multivariate models to ascertain their utility for
preventing depression in high-risk groups. Results: People are placed at a high risk
of depression when having symptoms of anxiety, functional impairments, two or
more chronic illnesses, and either a low attained educational level or below
average levels of mastery, while living without a partner. These risk profiles
correspond with groups no larger than 8.3% of the older population. Containing
the adverse effects of the risk factors would help to reduce the incidence of
depression by possibly as much as 48.7%, indicating that large health gains can
be generated, which can also be done efficiently with numbers-needed-to-betreated,
perhaps as small as three. Conclusion: Targeting prevention on the
selected high-risk groups is likely to become a cost-effective endeavor, because
optimal health gains can be generated efficiently in groups small enough to be
logistically manageable. The burden of illness associated with depression, particularly
depression, in aging populations underscores the public health significance
of such an approach.