The impact of incident depression on medication adherence in patients with type 2 diabetes.

BACKGROUND: Depression has been correlated with suboptimal adherence to antidiabetic drugs (ADs). Most studies on this topic were cross-sectional; thus, the directionality of this relationship could not be established. The objective of this study was to measure the association between incident depression and AD nonadherence among newly treated patients with diabetes. METHODS: We performed a population-based cohort study among new AD users using the Quebec public health insurance data. To avoid immortal time bias, we carried out depression diagnosis-time distribution matching by assigning a date of depression diagnosis to individuals without depression. Nonadherence (i.e.,<90% of days covered by≥1 AD) during the year following depression diagnosis (real or assigned date) was the outcome. Multivariate logistic regression analyses that adjusted for baseline adherence and other confounders were used to estimate the adjusted effect of depression on AD nonadherence. RESULTS: Between 2000 and 2006, we identified 3,106 new AD users with a subsequent diagnosis of depression and 70,633 without depression, of which 52% and 49% became non-adherent to AD treatment, respectively. Among patients with depression, 52.0% were considered AD non-adherent in the year after depression diagnosis compared with 49.0% of matched patients without depression. Depression was associated with AD nonadherence after accounting for baseline adherence and other confounders with an adjusted odds ratio of 1.24 (95% confidence interval: 1.13-1.37). CONCLUSIONS: The results suggest that depression is an independent risk factor for AD nonadherence. Patients with type 2 diabetes and depression might benefit from adherence-enhancing interventions.

Difficulty adhering to antidiabetic treatment: factors associated with persistence and compliance.

AIMS: This study aimed to assess the 1-year treatment persistence and compliance of new oral antidiabetic drug (OAD) users with their treatment, and to identify the factors associated with both persistence and compliance. METHODS: This population-based cohort study of new OAD users aged 18 years or above used the Quebec health insurance board databases. Those having a prescription filled for antidiabetic treatment during the period leading up to the 1-year anniversary of their first claim were considered to be persistent with their antidiabetic treatment. Of these patients, individuals with a medication possession ratio (MPR) greater or equal to 80% for OAD or insulin were deemed compliant. Also identified were the characteristics associated with both outcomes, using a multivariate logistic regression model. RESULTS: Our cohort consisted of 151,173 individuals, 119,832 (79.3%) of whom were considered persistent. Of these, 93,418 (78.0%) were also deemed compliant. Persistence and compliance were associated with older ages, living in a rural region, low socioeconomic status, having the first OAD prescribed by a general practitioner and a history of using five different drugs or more. People were less likely to be persistent and compliant if their initial OAD was a secretagogue and if they had consulted a physician eight times or more during the year prior to starting treatment. CONCLUSION: One year after OAD treatment initiation, 21% had discontinued their treatment and 22% of those still being treated were non-compliant. These results could help to tailor interventions aimed at optimizing the use of OAD treatments.