Impact of cancer on adherence to glucose-lowering drug treatment in individuals with diabetes

Abstract

Aims/hypothesis Adherence to glucose-lowering drug (GLD) treatment regimens is crucial for metabolic control and improving prognosis. Because a diagnosis of cancer might have an impact on adherence to medication, this study explored changes in adherence to GLDs following a cancer diagnosis.Methods All new users of GLDs between 1998 and 2011 who lived in the Eindhoven Cancer Registry-PHARMO Database Network catchment area were selected. Those with a primary cancer diagnosis during follow-up were considered cases and matched with eligible controls without cancer during followup. Medication possession ratio (MPR) was used as indicator for medication adherence. Segmented linear auto-regression analysis with interrupted time series was used to assess changes in MPR for cases compared with controls (i.e. overall trend) due to (any) cancer diagnosis and specific cancer types. Results From the 52,228 GLD users selected, 3,281 cases with cancer and 12,891 controls without cancer during follow-up were included in the study. In our analyses, before cancer diagnosis the MPR increased by 0.10% per month (95% CI 0.10, 0.10). Besides a significant drop in MPR at the time of cancer diagnosis of −6.3% (95% CI −6.5, −6.0), there was an ongoing, yet lower, monthly decline in MPR (−0.20%; 95% CI −0.21, −0.20) after cancer diagnosis. The largest drops in MPR at the time of cancer diagnosis, in the range of 11-15%, were seen among patients with stage IV disease and gastrointestinal or pulmonary cancers. Conclusions/interpretation Our findings indicate a clear decline in adherence to GLD treatment regimens following a cancer diagnosis. The reason for the decline in MPR needs to be further elucidated.

Impact of cancer on use of glucose-lowering drug treatment in individuals with diabetes: potential mechanisms. Reply to Pouwer F [letter]

“…As elaborated in our study [2] and in the contribution by Pouwer [1], we can conclude that the association between adherence to glucose-lowering treatment and cancer is probably explained by an interplay of factors. We thank Pouwer for his valuable additions regarding potential mechanisms to explain the complex association.…”

“…Cancer . Glucose-lowering drugs To the Editor: We thank Frans Pouwer for his comments on our study [1] exploring adherence to glucose-lowering drugs following a cancer diagnosis among individuals with diabetes [2]. Our findings revealed that there was a significant drop in the medication possession ratio at the time of cancer diagnosis, with the largest drops among patients with stage IV disease and gastrointestinal or pulmonary cancers.…”

Impact of cancer on use of glucose-lowering drug treatment in individuals with diabetes: potential mechanisms

“…They state that the reason for this decline needs to be further elucidated. In this letter, I would like to describe two potential mechanisms that were not discussed by Zanders et al in their paper [1]. First, weight loss might have played an important role.…”

“…To the Editor: In a very interesting and relevant study, based on the very large dataset from the Eindhoven Cancer Registry, Zanders et al investigated the potential impact of cancer on adherence to glucose-lowering drugs (GLDs; oral medication and/or insulin) in people with diabetes [1]. Their results showed a significant drop in the medication possession ratio, which was used as an indicator for medication adherence.…”

Statin Adherence After Ischemic Stroke or Transient Ischemic Attack Is Associated With Clinical Outcome

“…The statin adherence of each patient was defined using MPR, 28 which was calculated as the total days covered by prescribed statins in the 1 year after initiation of statin therapy divided by 365 days. Eligible patients were divided into 3 groups according to MPR: good adherence (n=2,274; mean age, 65.2 years; male, 49.9%; MPR >80%); intermittent adherence (n=3,710; mean age, 64.8 years; male, 50.8%; MPR=40-80%), and poor adherence (n=9,424; mean age, 65.1 years; male, 51.7%; MPR <40%; Figure 1).…”