Health care system and patient costs associated with receipt of minimally adequate treatment for depression and anxiety disorders in older adults

BACKGROUND: Depression and anxiety disorders in older adults are associated with a great burden. Research has shown that less than 50% of adults receive adequate treatment in primary care settings for these disorders. Rare are the studies however assessing adequate treatment in older adults and associated costs from the societal perspective. Given the episodic nature of common mental disorders, this study aims to assess the three-year costs from a restricted societal perspective (including health system and patient perspectives) associated with receipt of minimally adequate treatment for depression and anxiety disorders in older adults consulting in primary care. METHODS: This primary care cohort study included 358 older adults aged 65 years and older with either a self-reported or physician diagnosis of depression or an anxiety disorder covered under Quebec’s public drug plan. Receipt of minimally adequate treatment was assessed according to Canadian guidelines and relevant reports. Outpatient and inpatient service use, medication costs and physician billing fees were obtained from provincial administrative databases. Unit costs were calculated using provincial financial and activity reports and relevant literature. A propensity score was created to estimate the probability of receiving minimally adequate treatment and the inverse probability was used as a weight in analyses. Generalized linear models, with gamma distribution and log link, were conducted to assess the association between receipt of minimally adequate treatment and costs. RESULTS: Overall, receipt of minimally adequate treatment was associated with increased three-year costs averaging $5752, $536, $6266 for the health system, patient and societal perspectives, respectively, compared to those not receiving minimally adequate treatment. From the health system perspective, participants receiving minimally adequate treatment had higher costs related to emergency department (ED) (difference: $457, p = 0.001) and outpatient visits (difference: $620, p < 0.001), inpatient stays (difference: $2564, p = 0.025), drug prescriptions (difference: $1243, p = 0.002) and physician fees (difference: $1224, p < 0.001). From the patient perspective, receipt of minimally adequate treatment was associated with higher costs related to loss of productivity related to ED (difference: $213, p < 0.001) and outpatient visits (difference: $89, p < 0.001). CONCLUSIONS: Older adults receiving minimally adequate treatment for depression and anxiety disorders incurred higher societal costs reaching $2089 annually compared to older adults not receiving minimally adequate treatment. The main cost drivers were attributable to hospitalizations and prescription drug costs.