Disability and depression among high utilizers of health care. A longitudinal analysis

We evaluated, among depressed medical patients who are high utilizers of health care, whether improved vs unimproved depression is associated with differences in the course of functional disability. At baseline, 6 months, and 12 months, depression and disability were assessed among a sample of enrollees in health maintenance organizations (N = 145) in the top decile of users of ambulatory health care who exceeded the 70th percentile of health maintenance organization population norms for depression. Improved depression was defined as a reduction of at least one third in depressive symptoms averaged across the two follow-up times. At the 12-month follow-up, persons with severe-improved depression experienced a 36% reduction in disability days (79 days per year to 51 days per year) and a 45% reduction in disability score. Persons with moderate-improved depression experienced a 72% reduction in disability days (62 days per year to 18 days per year) and a 40% reduction in disability score. In contrast, persons with severe-unimproved depression reported 134 disability days per year at baseline, while persons with moderate-unimproved depression reported 77 disability days per year at baseline. Neither group with unimproved depression showed improvement in either disability days or disability score during the 1-year follow-up period. High utilizers of health care with severe-unimproved depression were more likely to have current major depression and to be unemployed. Improved (relative to unimproved) depression was associated with borderline differences in the severity of physical disease and in the percent married. We conclude that depression and disability showed synchrony in change over time. However, depression and disability may show synchrony in change with disability because both depression and disability are controlled by some other factor that influences the chronicity of depression (eg, chronic disease or personality disorder). The finding of synchronous change of depression and disability provides a rationale for randomized controlled trials of depression treatments among depressed and disabled medical patients to determine whether psychiatric intervention might improve functional status in such patients. Such research is needed to determine whether there is a causal relationship between depression offset and reductions in functional disability.