Anti-diabetic medication adherence and cardiovascular outcomes in patients with cancer: a nationwide population-based cohort study

Abstract Background Diabetes is an important cause of morbidity, which predisposes patients to major cardiovascular (CV) events and mortality. However, clinical implications of anti-diabetic medication adherence for cancer patients have not been well studied in the real clinical practice. Purpose This study aimed to evaluate the association between anti-diabetic medication adherence and clinical outcomes in adult patients with cancer. Methods Using the prospective nationwide cohort (Korean NHIS-NSC), we extracted adult cancer patients treated with anti-diabetic medications. Based on the medication possession ratio (MPR) value, participants were divided into 3 groups: good (MPR ≥0.8), moderate (0.5 ≤ MPR < 0.8), and poor (MPR<0.5) adherence groups. The primary outcomes were overall and CV mortality. The secondary outcome was CV events requiring hospitalization due to major CV diseases. Results Among 8,052 cancer patients with concomitant diabetes, 59.4% were nonadherence group (21.5% were moderate and 37.9% were poor adherence group). Over a median of 8.4 years of follow-up, 1,475 deaths and 2,931 CV events occurred. Compared to the good adherence group, the moderate and poor adherence groups had a 1.61-fold and 2.00-fold increased risk for overall mortality; and 1.66-fold and 1.98-fold elevated risk for CV mortality, respectively, after adjustment for possible confounders. Furthermore, moderate and poor adherence groups had a 1.29-fold and 1.38-fold elevated risk for new-onset CV events. These trends were consistent across CV event subtypes. Conclusions Nonadherence to anti-diabetic medication is common in cancer patients and is associated with worse clinical outcomes in adult cancer patients with diabetes. More attention should be paid to improve adherence to anti-diabetic medication among patients with cancer.