Relationship Between Continuity of Ambulatory Care and Medication Adherence in Adult Patients With Type 2 Diabetes in Korea: A Longitudinal Analysis

Background: Medication adherence is the most important factor in the proper management of patients with diabetes. Considering the importance of informational continuity in a changing world, it could be meaningful to improve institution-level continuity of care and its positive relationship with medication adherence. Objectives: We examined the relationship between institution-level continuity of ambulatory care and medication adherence in adult patients with type 2 diabetes receiving a new hypoglycemic prescription and sought to determine whether an improvement in medication adherence could be achieved through an ongoing relationship between the patient and the medical care institution. Research Design and Subjects: This was a longitudinal study of 23,034 patients aged 20 years and older enrolled in the Korea National Health Insurance (KNHI) program and first diagnosed with type 2 diabetes in 2004. The patients were followed-up for 4 years using claims data to measure continuity of ambulatory care and adherence to oral antihyperglycemic medications. The Continuity of Care Index (COCI) was calculated on the institution level as a measure of continuity and the medication possession ratio (MPR) was used as a measure of adherence. Results: After adjusting for confounding variables, the odds of being medication adherent (MPR ≥ 0.8) increased as the COCI increased [0.2 ≤ COCI < 0.4, odds ratio (OR) = 2.20; 0.4 ≤ COCI < 0.6, OR = 3.46; 0.6 ≤ COCI < 0.8, OR = 4.76; 0.8 ≤ COCI < 1.0, OR = 4.43; COCI = 1.0, OR = 7.24]. Conclusions: Institution-level continuity of ambulatory care was positively associated with medication adherence, which suggested that a high concentration of ambulatory care visits, whether it's a physician or an institution, could facilitate delivery of proper medical services to and increases medication adherence among patients with type 2 diabetes, and that institution-level continuity of ambulatory care could be an effective index for assessing the quality of chronic care in the fragmented health care delivery system as in Korea.