Relationship of Number of Clinic Visits to Response during Placebo-Controlled Antidepressant Trials in Late Life Depression

Objectives: To determine if the number of clinic visits affects placebo or drug response in antidepressant trials of late life major depression. Method: A previous systematic review of placebo-controlled antidepressant trials in late life depression was updated. Selected trials randomized patients to antidepressant or placebo and included community dwelling patients aged 60 and older, with Major Depressive Disorder. The association of number of visits with response in the placebo and drug groups was examined adjusting for trial duration and the duration-visit interaction. Regressions were also performed to determine if the relationship between number of visits and response differed between treatment groups and to assess if lifetime duration of MDD influenced the visit-response relationship in the placebo group. Results: Thirteen trials with 5028 patients were selected. After controlling for trial duration, number of visits was significantly associated response in the placebo group (χ2=4.69, p=0.03) but not the drug group (χ2=0.38, p=0.54); however, the association of response and number of visits did not differ significantly between the drug and placebo groups. Response rates appeared to increase with more visits in each group. Conclusions: In late life depressed patients response rates increase with more frequent visits during placebo administration. Although this association was not significant in the group receiving antidepressants and clinical management, analysis of the interaction of several variables is limited by the small number of trials and we would be cautious about concluding that number of visits does not contribute to drug response.