Medication nonadherence in diabetes: longitudinal effects on costs and potential cost savings from improvement.
OBJECTIVE
To examine the longitudinal effects of medication nonadherence (MNA) on key costs and estimate potential savings from increased adherence using a novel methodology that accounts for shared correlation among cost categories.


METHODS
Veterans with type 2 diabetes (740,195) were followed from January 2002 until death, loss to follow-up, or December 2006. A novel multivariate, generalized, linear, mixed modeling approach was used to assess the differential effect of MNA, defined as medication possession ratio (MPR) ≥0.8 on healthcare costs. A sensitivity analysis was performed to assess potential cost savings at different MNA levels using the Consumer Price Index to adjust estimates to 2012 dollar value.


RESULTS
Mean MPR for the full sample over 5 years was 0.78, with a mean of 0.93 for the adherent group and 0.58 for the MNA group. In fully adjusted models, all annual cost categories increased ∼3% per year (P = 0.001) during the 5-year study time period. MNA was associated with a 37% lower pharmacy cost, 7% lower outpatient cost, and 41% higher inpatient cost. Based on sensitivity analyses, improving adherence in the MNA group would result in annual estimated cost savings ranging from ∼$661 million (MPR <0.6 vs. ≥0.6) to ∼$1.16 billion (MPR <1 vs. 1). Maximal incremental annual savings would occur by raising MPR from <0.8 to ≥0.8 ($204,530,778) among MNA subjects.


CONCLUSIONS
Aggressive strategies and policies are needed to achieve optimal medication adherence in diabetes. Such approaches may further the so-called "triple aim" of achieving better health, better quality care, and lower cost.
Center for Disease Prevention and Health Interventions for Diverse Populations, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA. egedel@musc.edu
Leonard E
LE
Egede
Mulugeta
M
Gebregziabher
Clara E
CE
Dismuke
Cheryl P
CP
Lynch
R Neal
RN
Axon
Yumin
Y
Zhao
Patrick D
PD
Mauldin
D017046:Cost Savings / Q000706:statistics & numerical data; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D015233:Models, Statistical; D016903:Drug Monitoring
D007004:Hypoglycemic Agents