The impact of depression medications on oral antidiabetic drug adherence in patients with diabetes and depression

Abstract

Aims: To compare adherence and persistence to oral antidiabetic drugs (OAD) between patients who are new users of second generation antipsychotics (SGA) versus new users of other depression therapies in adults with type 2 diabetes mellitus (T2DM) and major depressive disorder (MDD).

Methods: Adults 18-64 years with previously-treated T2DM and MDD (past OAD and SSRI/SNRI use) who are new users of SGA or non-SGA therapies (bupropion, lithium, mirtazapine, thyroid hormone, tricyclic antidepressant) were identified in the 2009-2015 MarketScan® Commercial Claims and Encounters database. Multivariate regression models were used to determine the odds of a ≥10% decline in OAD adherence over 180- and 365-days, and time to OAD discontinuation, adjusting for differences between groups.

Results: A total of 8664 (21.5% SGA), 8311 (22.1% SGA), and 17,524 (21.3% SGA) patients met inclusion criteria for the 180-day adherence, 365-day adherence, and persistence cohorts, respectively. Over 180-days, 16.6% of SGA and 13.3% of non-SGA initiators had a ≥10% decline in OAD adherence (adjusted odds ratio [OR] = 1.41, 95% CI 1.21-1.63). Over 365-days, 22.3% of SGA and 18.9% of non-SGA initiators had a ≥ 10% decline (OR = 1.34, 95% CI 1.17-1.53). Time to OAD discontinuation was similar between groups (adjusted hazard ratio = 1.03, 95% CI 0.94-1.12).

Conclusion: Use of SGA was associated with a 1.3-1.4 times higher odds of a ≥10% decline in OAD adherence. Adherence to OAD is critical for optimal diabetes control and reductions in this magnitude may impact A1C. Close monitoring of OAD adherence after SGA initiation is warranted.

Keywords: Antidepressants; Antipsychotics; Depression; Healthcare administration claims; Medication adherence; Type 2 diabetes mellitus.

Figure 1. Non-adherence to oral antidiabetic drug (OAD) therapy comparing second generation antipsychotic (SGA) initiators versus non-SGA initiators in primary and sensitivity analyses

The adjusted odds ratios (OR) and 95% confidence intervals (CI) are graphed for the primary analysis (i.e. ≥10% decline in adherence to OAD comparing the 180 days post-index versus the 180 days pre-index, where adherence was estimated using the average proportion of days covered (PDC) for patients using multiple diabetes drug classes) and the sensitivity analyses where adherence was measured: 1) over 365 days compared to 180 days in the main analysis; 2) using a 80% PDC cut-off where non-adherence was defined as PDC<0.8 calculated over the 180 and 365 days post-index compared to a 10% decline in the main analysis; 3) using the “Diabetes All Class Rate” instead of the average PDC for patients using multiple diabetes drug classes in the main analysis; 4) measuring a ≥20% decline over the 180 and 365 days post versus pre-index compared to 10% decline in the main analysis; and 5) excluding patients with any inpatient admission.