To determine whether subjects with major depressive disorder (MDD) that switch/augment therapy have higher health care costs and productivity losses compared to those who stay on therapy.

Data were derived from a national-employment-based medical and pharmacy claims database. Index date was defined based on pre-specified antidepressant prescription claims between 7/1/2002-3/31/2005. Subjects were treatment-naïve 6-months prior to index-date, continuously enrolled, and had at least one outpatient-based medical claim for MDD (ICD-9=296.2x/296.3x) during study period. Study cohorts [switchers/augmenters/maintainers] were defined based on antidepressant prescription refill pattern 12-months post index therapy. Productivity losses were defined as days absent from work for medical visits multiplied by average daily wage. Per-patient-per-year (PPPY) post-index costs were statistically (Type-1 error <0.05) compared multivariately (generalized-linear-model) and productivity losses were compared univariately (Wilcoxon-tests).

Of 7,273 individuals who meet study criteria, 40.3% (n=2,931), 1.5% (n=109), and 58.2% (n=4,233) were classified as switchers, augmenters, and maintainers, respectively. Baseline characteristics were similar across the three cohorts. Average total and depression-related healthcare costs were 1.51-1.92 times (p<.01) and 1.52-1.42 times (p<.001) greater for switchers ($9,288 and $1,388) and augmenters ($9,350 and $1,027) vs. maintainers ($6,151 and $723) after controlling for baseline characteristics. Average total and depression-related productivity losses PPPY were $2,081/$680 for switchers, $2,010/$587 for augmenters and $1,424/$437 for maintainers. These productivity losses were greater for switchers and augmenters compared to maintainers (p<.001).

MDD subjects that change therapy within 12-months of treatment initiation have higher resource costs and productivity losses compared to those who stay on the same therapy.