Levels of disability in major depression: findings from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

BACKGROUND: Information on the distribution of disability associated with major depression (MD) across different groups of patients is of interest to health policy and planning. We examined the associations of severity and type (a single or recurrent episode) of MD with disability in a Dutch general population sample.
METHODS: We used data from the first wave (1996) of the Netherlands Mental Health Survey and Incidence Study (NEMESIS). MD 'severity' and 'type' were diagnosed with the help of the Composite International Diagnostic Interview according to DSM-III-R criteria. SF-36 scores, days ill in bed and days absent from work were taken as indicators of disability. The differences in these variables were studied by means of variance and regression analysis.
RESULTS: Recurrent MD was found not to be associated with more disability than single episode MD. Higher 'severity' classes were associated with more disability. However, the degree of disability between 'moderate' and 'severe' MD differed only very slightly. The difference in disability between non-depressed and mildly depressed individuals had a larger effect than between each successive pair of 'severity' classes.
CONCLUSIONS: Three groups of MD can be distinguished based on the associated degree of disability: 'mild', 'moderate to severe' and 'severe with psychotic features'. In the future, these groups can be used to describe the distribution of disability in the depressed population. The marked difference between 'mild' MD and no MD suggests that 'mild' cases should be considered relevant.