Maintenance strategies for unipolar depression: an observational study of levels of treatment and recurrence

Background: This paper analyses data from a large observational study of the course of affective illness to provide insight into the duration and dose of effective maintenance therapies. Methods: The data are 236 unipolar patients who had received antidepressants during recovery and were followed for affective recurrence for up to 5 years. Using data on the naturally selected somatic treatments, we have conducted analyses that adjust for the potential confounding effects of prognosis and treatment intensity to estimate the causal effect of level of medication on the course of recurrence. Results: The results of these analyses show that it is important for patients to remain on the level of somatotherapy used to treat the acute episode for the initial 8 months after symptoms have abated. After that time, the rate of recurrence for patients with fewer than five previous episodes is approximately 1% per week or less at all levels of medication (including discontinuation). Patients who had experienced more than several recurrences are at greater risk of recurrence and continue to benefit from any level of medication during the first year after recovery. Conclusions: The CDS analyses reported here suggest that effective maintenance strategies for all but highly recurrent patients may be a middle road, opting for full-dose strategies of limited duration. These results have implications at both the policy and the clinical level, given the need to consider both monetary and nonmonetary costs (side-effects) associated with continued pharmacotherapy during remission. Limitations: The observational design of the CDS limits the degree to which cause and effect relationships can be inferred from the observed associations.