Health-related quality of life outcomes, economic burden, and associated costs among diagnosed and undiagnosed depression patients in Japan.

Purpose: Depression is associated with substantial health and economic burden. This study examined the impact of diagnosed and undiagnosed depression on health-related outcomes and costs among Japanese adults.

Methods: A retrospective, observational study was conducted using 2012-2014 Japan National Health and Wellness Survey (N=83,504) data. Differences between respondents diagnosed with depression (n=2,843) and undiagnosed with depression (weighted n=2,717) and controls without depression (weighted n=2,801) in health-related quality of life, impairment to work productivity and daily activities (Work Productivity and Activity Impairment Questionnaire), health care resource utilization, and annual costs were evaluated. Propensity score weighting and weighted generalized linear models were used to compare groups on the outcome variables, after adjusting for covariates.

Results: Overall, respondents with undiagnosed depression had significantly better outcomes than those diagnosed with depression, but significantly worse outcomes than controls (for all, <0.001). The mean Mental Component Summary scores were lower in the diagnosed group when compared with undiagnosed respondents and controls (33.2 vs 34.5 vs 48.6). Similar findings were obtained for mean Physical Component Summary (49.2 vs 49.5 vs 52.8) and health state utility scores (0.61 vs 0.62 vs 0.76). Additionally, the diagnosed group reported greater absenteeism (13.1 vs 6.6 vs 2.5%), presenteeism (41.4 vs 38.1 vs 18.8%), overall work productivity impairment (47.2 vs 41.1 vs 20.2%), and activity impairment (48.4 vs 43.3 vs 21.1%) than the undiagnosed and control groups, respectively. Consistently, patients with diagnosed depression had higher annual per patient direct (1.6-fold) and indirect costs (1.1-fold) than those in the undiagnosed depression group.

Conclusion: Diagnosed depression was associated with lower health-related quality of life and greater impairment in work productivity and daily activities, higher health care resource utilization, and higher costs, compared with undiagnosed respondents and controls. These study findings suggest a need for greater awareness of depression symptoms among Japanese adults, which is needed to facilitate proper diagnosis and treatment.