An Analysis to Assess Non-adherence in People With Type 2 Diabetes

Non-adherence is defined as: "the extent to which a person's behaviour - taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations from a health care provider". Adherence to chronic disease medications remains poor and it is estimated that around one third to half of all patients become nonadherent. Medication non-adherence is a risk factor for adverse clinical outcomes, including hospital admissions, and costs the U.S. health care system over $100 billion annually. In the UK, it is estimated that up to 50% of patients do not take their prescribed medications and its costs the NHS £4 billion annually.

Non-adherence has been measured by various methods including patient self-reported questionnaires and by looking at pharmacy refill records and electronic monitoring devices (EMDs). There was until recently the lack of a clinically useful tool to assess non-adherence in a simple, reliable method. We have recently developed an innovative, first in the world chemical test to objectively ascertain adherence by testing for presence of medications in a spot urine sample. This test uses a high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of spot urine samples to detect 160 commonly prescribed cardiovascular medications including those for diabetes. The method is robust and reliable and has been developed from techniques used in Forensic Medicine. We, in Leicester, utilise the test routinely in the Hypertension Clinic and have set up the first National Centre for Adherence Testing (NCAT). We now receive samples from around 40 centres across UK and have analysed more than 64000 samples to date. In our experience, it is well accepted by patients, it provides confidence to the clinician about non-adherence and helps initiate an objective discussion with patients. The test helps patients understand that the absence of medications in their body is linked with the suboptimal control of their illness. The test helps explore the reasons for non-adherence and tailor therapy to patient's needs. The use of the tests is now becoming accepted practice in hypertensive patients.

A meta-analysis that included more than 300,000 patients with diabetes showed that good adherence was associated with reduced all-cause mortality hospitalisation. The studies included in the meta-analysis used pharmacy refill records. Chemical testing for non-adherence has not been used to investigate the extent of non-adherence in diabetes or in patients in primary care.

Therefore, it would of utmost interest to confirm non-adherence rates using this method and compare it with commonly used tools such as pharmacy refill rates and patient self-reported measures of non-adherence. Overcoming this gap of knowledge is the primary aim of the study.

The study is designed as a prospective cohort study. We aim to study non-adherence in patients diagnosed with type 2 diabetes and plan to recruit 600 patients attending primary care in Leicestershire. Patients will be recruited if they have uncontrolled diabetes (HbA1c ≥ 7.5%) and are on at least one oral antidiabetic and one other cardiovascular medication that is part of our medication screen. This excludes aspirin and simvastatin as they are not on our panel.

The patients will be those attending their annual diabetes review in primary care. The urine and/or blood sample provided by patients as a part of their visit will be analysed for adherence testing. The sample will be collected by the patient's direct clinical care team and forwarded to the Department of Metabolic Medicine and Chemical Pathology (DMMCP). It will then be tested for the presence of prescribed medications by high performance liquid chromatography-tandem mass spectrometer (LC-MS/MS). There will be no extra samples obtained from patients.

Patients will also be asked to complete a medication adherence questionnaire which will ask questions about their medication taking behaviour. Patient data including demographic data, list of medications and co-morbidities, details of cardiovascular risk factors will be collected in a coded anonymised fashion. GP medication records will also be accessed by the patient's direct clinical care team. The laboratory analysts will be unaware of the clinical details of the patients. The results will not be sent back to the treating clinician or the patients. The results of the anonymised samples will be sent to the research team.

A patient research ID will be created by the patient's direct clinical care team at the GP practice after patients are consented and then samples then sent to the lab for analysis.

The study will take place over a duration of two years. Screening and recruiting of patients will take place over 9 months. Samples and data collection will be carried out in tandem and will be completed over 12 months. The data will then be analysed and reviewed before being written up as a report, which will take place over 3 months.