A diagnosis of type 2 diabetes based on ICD-10 codes included principal diagnosis and up to four additional accompanying diagnoses, in order of clinical significance in the current condition. Patients were classified as having type 2 diabetes when they had at least one service claim with a diagnosis of type 2 diabetes, either in outpatient or inpatient care, and were prescribed at least one antidiabetic drug anytime in a given year to exclude prediabetes or non-diabetic subjects.
Antidiabetic drugs dispensed in the pharmacy during the study period in Korea consisted of seven classes (i.e., SU, biguanide, alpha-glucosidase inhibitor, TZD, DPP-4 inhibitors, meglitinide, and insulin; Supplement Table S1). The GLP-1 agonist was introduced in Korea by the end of 2008; however, health insurance coverage was available only in November 2010 with strict conditions. Therefore, the GLP-1 agonist was not included in this analysis. We obtained the annual number of prescriptions for all antidiabetic drug classes, including insulin, during the study period.
For information on prescriptions, the name of the drug, date prescribed, days of supply, quantity dispensed, and price of each tablet or injection were collected. Insulin was not classified as intermediate-, short-, or long-acting forms, but was counted as one class of antidiabetic medication. If the patients took more than two different classes of antidiabetic drugs, either as a fixed-dose combination or different pills, they were defined as receiving combination therapy.[15 (link),16 (link)] We classified the medication as monotherapy, dual therapy, and triple therapy.
To investigate drug adherence, the medication possession ratio (MPR) was used and defined as a cumulative medication adherence of more than 80% (292 days) per year among patients with type 2 diabetes prescribed in a given year and included data only on antidiabetic drug prescriptions dispensed from pharmacies.[18 (link),19 (link)] For evaluation of medication costs, we used the database of pharmacy claims, and confined them to the cost of antidiabetic drugs.
Antidiabetic drugs dispensed in the pharmacy during the study period in Korea consisted of seven classes (i.e., SU, biguanide, alpha-glucosidase inhibitor, TZD, DPP-4 inhibitors, meglitinide, and insulin; Supplement Table S1). The GLP-1 agonist was introduced in Korea by the end of 2008; however, health insurance coverage was available only in November 2010 with strict conditions. Therefore, the GLP-1 agonist was not included in this analysis. We obtained the annual number of prescriptions for all antidiabetic drug classes, including insulin, during the study period.
For information on prescriptions, the name of the drug, date prescribed, days of supply, quantity dispensed, and price of each tablet or injection were collected. Insulin was not classified as intermediate-, short-, or long-acting forms, but was counted as one class of antidiabetic medication. If the patients took more than two different classes of antidiabetic drugs, either as a fixed-dose combination or different pills, they were defined as receiving combination therapy.[15 (link),16 (link)] We classified the medication as monotherapy, dual therapy, and triple therapy.
To investigate drug adherence, the medication possession ratio (MPR) was used and defined as a cumulative medication adherence of more than 80% (292 days) per year among patients with type 2 diabetes prescribed in a given year and included data only on antidiabetic drug prescriptions dispensed from pharmacies.[18 (link),19 (link)] For evaluation of medication costs, we used the database of pharmacy claims, and confined them to the cost of antidiabetic drugs.
