Ethnicity and adherence to oral hypoglycaemic agents in T2DM

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Lay Summary

Reduced medication adherence in type 2 diabetes has been connected with increased mortality, poorer diabetes control and increased rates of hospital admission. An association between ethnic minority group and rates of medication adherence has been reported in the literature but most studies have looked at small patient populations at a sub-national level, and mainly in the United States. No study examining this association has been conducted in the UK.

Furthermore, there is controversy as to whether patients from ethnic minority groups have worse diabetes control when compared to White ethnic groups. Some UK work, as well as papers from the USA and Sweden, has shown this to be the case, whilst other more recent UK studies have suggested there is no difference between ethnic groups.

The purpose of this study is to use a large national database analysis to determine whether there is an association between ethnicity and adherence to prescriptions for oral anti-diabetes drugs. We also aim to determine whether there is an association between ethnicity and diabetes control (as measured by HbA1c) and the impact of adherence on this.

Given the higher prevalence of diabetes among ethnic minority groups, this work may contribute to reducing health inequalities and improving outcomes in type 2 diabetes.

Technical Summary

The objectives of this two-year (2013-2015) cross-sectional study are to determine whether there are associations between ethnicity and medication adherence to oral hypoglycaemic agents (OHAs), and ethnicity and HbA1c levels, in UK patients with type 2 diabetes mellitus (T2DM). We will also test whether adjustment for medication adherence alters the predictive value of ethnicity for HbA1c levels.

The population will include all patients >18-years with T2DM using OHAs. Patients will be grouped by ethnic category using the standard Office for National Statistics (ONS) 5-category classification. Medication adherence will be defined and analysed as ‘proportion of days covered’ (PDC), both as a continuous variable, and PDC ≥0.8 (binary variable). Similarly continuous HbA1c (= mean over 2-year period) and binary HbA1c (= continuous measure collapsed into < or > 7.5% categories) outcome variables will be analysed.

Linear and logistic regression analyses will be used to determine whether there are associations between ethnicity and these outcome variables. We will calculate unadjusted and adjusted coefficients and odds ratios, with Huber-White standard errors, with the adjusted measures of effect accounting for various previously identified potential confounders. These confounders have been identified from extensive literature review and include demographic and socioeconomic factors, other prescriptions and comorbidities.


Michael Soljak - Chief Investigator - Imperial College London
Robert Watson - Corresponding Applicant - Imperial College London
Ailsa McKay - Collaborator - Imperial College London
Azeem Majeed - Collaborator - Imperial College London
Jonathan Valabhji - Collaborator - Imperial College London
Roger Newson - Collaborator - Imperial College London


HES Admitted Patient Care;HES Outpatient;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation