Factors Affecting Sustained Medication Adherence and Its Impact on Health Care Utilization in Patients with Diabetes.

OBJECTIVE To identify factors associated with years of medication adherence and to examine the relationship between years of adherence and health care utilization. METHODS This retrospective analysis used administrative data from adult patients with diabetes enrolled in health plan in Hawaii for four years (n= 23,450 patients). Ordered logistic regression was used to examine factors related to years of medication adherence for three types of medications (anti-diabetic, antihypertensive, lipid-lowering). Multivariable logistic regression and negative binomial regression were used to examine relationship between years of adherence and health care utilization (hospitalizations and emergency department visits). KEY FINDINGS Adherence to any of the medications for all four years was significantly associated with lower odds of a hospitalization or emergency department visit in the third year. The magnitude of reduction in utilization was greater for adherence to anti-diabetic and lipid-lowering medications, at 31% compared to 22% for antihypertensives. The 9% of patients who were adherent to all three types of medications for all four years showed a reduction of 53%. CONCLUSIONS Improvement is needed in medication adherence across all three types of medication. Interventions may need to target younger adults, women, patients with congestive heart failure, Filipinos and Native Hawaiians.