The Productivity Impact Model is meant to show estimates of revenue improvement due to treating depression. In order to avoid overstating the effects of diagnosis and treatment, conservative default values are provided. These estimates are based on assumptions made regarding the effects of depression and its treatment of workers. A continually expanding body of literature supports these assumptions. New publications show the importance to individual companies of diagnosing and treating depression. A summary of this literature, related to the important model assumptions, is described below.

1. Employees affected by depression miss more work.

This assumption has been well documented in the literature. Estimates vary widely for each study and for each sample. We have used a conservative range of 22 to 32 workdays missed per year due to depression, which includes both absenteeism and presenteeism. Published literature has shown a range of 10 to 90 workdays missed per year.

2. Employees affected by depression incur higher medical costs.

While not as extensive as the literature on absenteeism, several studies present clinical evidence that depressed individuals have higher medical costs than non-depressed individuals. These studies analyzed claims data, were cross-sectional, or longitudinal. A review of these studies indicated a default range of $1,000 to $2,000 for higher medical costs due to depression is appropriate for use in this model. See a more detailed explanation for this estimate.

3. It costs companies money when workers miss work due to depression.

Given that assumption #1 is true, we assume that companies spend additional money with hiring and training more workers to cover lost time due to absenteeism/presenteeism. Absenteeism and presenteeism may affect a company in other negative ways that could result in lost revenue, including the effects on employee morale. Given that assumption #2 is true, additional money will be spent on medical care of these depressed individuals.

4. Absenteeism and medical costs can be reduced when depression is treated successfully.

Clinical studies have supported this assumption. Although the overall estimates vary for each individual study, they consistently show a positive effect across a variety of samples and treatment conditions. The Productivity Impact Model uses a default value of 51% reduction in absenteeism/presenteeism under usual care and 77% under enhanced care. This may be a conservative estimate, given that some recent studies show an average reduction of more than 70% in absenteeism/presenteeism.

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