Adherence to Oral Glucose-Lowering Therapies and Associations With 1-Year HbA1c: A Retrospective Cohort Analysis in a Large Primary Care Database

Abstract

OBJECTIVEThe impact of taking oral glucose-lowering medicines intermittently, rather than as recommended, is unclear. We conducted a retrospective cohort study using community-acquired U.K. clinical data (Clinical Practice Research Database [CPRD] and GoDARTS database) to examine the prevalence of nonadherence to treatment for type 2 diabetes and investigate its potential impact on HbA 1c reduction stratified by type of glucose-lowering medication. RESEARCH DESIGN AND METHODSData were extracted for patients treated between 2004 and 2014 who were newly prescribed metformin, sulfonylurea, thiazolidinedione, or dipeptidyl peptidase 4 inhibitors and who continued to obtain prescriptions over 1 year. Cohorts were defined by prescribed medication type, and good adherence was defined as a medication possession ratio ‡0.8. Linear regression was used to determine potential associations between adherence and 1-year baseline-adjusted HbA 1c reduction. RESULTSIn CPRD and GoDARTS, 13% and 15% of patients, respectively, were nonadherent. Proportions of nonadherent patients varied by the oral glucose-lowering treatment prescribed (range 8.6% [thiazolidinedione]

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“…Adherence to oral glucose‐lowering therapies is a major problem in diabetes, with up to two‐thirds of patients not taking their medication as prescribed . Poor medication adherence is associated with poor glycaemic response, with patients who take <80% of their intended medication achieving half the expected reduction in glycated haemoglobin (HbA1c) …”

Management of type 2 diabetes: the current situation and key opportunities to improve care in the UK

“…The result of inadequate response to single therapy is often a complex prescribing pattern, which has implications for patients and physicians. The complexity of treatment regimen is inversely associated with adherence and, in turn, poor adherence is associated with smaller reductions in HbA1c . For physicians, interpreting and implementing clinical guidelines in the context of an individual patient can be a daunting prospect, further complicated by the wide range of treatment regimens now available.…”

Adherence to antihyperglycemic treatment: a work in progress

“…Non-adherence to oral antidiabetic agents, defined as a medication possession ratio <0.8, ranges between 13-31% [4,5]. Interestingly, adherence rates to oral agents appear to be lowest with metformin, the first-line agent for management of T2DM [4].…”

“…Interestingly, adherence rates to oral agents appear to be lowest with metformin, the first-line agent for management of T2DM [4].…”

“…Importantly, adherence to fixed-dose combinations of oral antidiabetic treatments is better than adherence to free drug combinations [7]. Not surprisingly, non-adherence to treatment is consistently associated with poorer glycemic control; HbA 1c levels are higher by 0.4-0.7% in nonadherent compared with adherent patients [4]. Younger age, female sex, lower education, lower income and higher out-of-pocket costs are independently associated with lower adherence to antihyperglycemic treatment [5].…”