Long-term follow up of concomitant medication use in type 2 diabetes patients: A cohort study

Abstract

Background: Concomitant disease and associated drug use is frequent in patients with type 2 diabetes mellitus. However, data on longitudinal changes in the prevalence of co-medication in such patients is limited. Objectives: To assess changes in the prevalence of concomitant medication use in patients with type 2 diabetes before and after initiation with oral antidiabetic agents (OAD). Methods: A cohort study was performed among new users of OAD aged ≥ 35 years, who were enrolled in the Diabetes Care System (DCS) in the Dutch region of West-Friesland (200,000 inhabitants). Patients receiving care from the DCS were linked to drug dispensing data obtained from 15 community pharmacies and two dispensing general practices in the region. The study period was between 1998 and 2007. The prevalence of medication use was assessed up to 10 years before and after initiation of OAD. Drugs evaluated included cardiovascular (CV) drugs and statins, but also included a range of non-CV drugs like antidepressants, antipsychotics, benzodiazepines, antibiotics, NSAIDs, respiratory medication and proton pump inhibitors. Results: We identified 2,933 incident users of OAD (51.9% men, mean age 61 years). The prevalence of drug use gradually increased with time for nearly any type of medication. However, the initiation of OAD triggered a shift in the prevalence of CV drug use. In the year prior to initiation, 58.7% of the patients used CV drugs, which increased to 73.9% in the first year after. Renin angiotensin aldosterone system inhibitors and statins attributed most to this increase. Also, the proportion of patients using more than one CV drug increased steadily over time. Stratification according to age and sex showed similar patterns with this shift being more pronounced in younger patients and men. The prevalence of non-CV medication use increased steadily, mostly due to a rise in the use of antibiotics, drugs for gastroesophageal reflux disease and eye medication. Conclusions: The increase in concomitant medication use in patients with type 2 diabetes was mostly attributable to an increase of cardiovascular medication according to guidelines aimed at prevention of cardiovascular disease.