Clinical Comparative Effectiveness of Independent Non-Medical Prescribers for Type 2 Diabetes

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Abstract

Independent and supplementary prescribing are the two main forms of non-medical prescribing (NMP) that have been practised in the UK since 2006. Most available studies have qualitatively investigated the impact of NMP, especially in primary care. This may be due to the fact that prescriptions are issued mainly by general practitioners in primary care. This PhD thesis aimed at investigating the clinical effectiveness of independent pharmacist and diabetes specialist nurse (DSN) prescribers in the management of patients with type 2 diabetes at outpatient clinics in hospitals.A literature review was firstly conducted to explore the current research on NMP around the world and the UK. A systematic review of the previously published randomised control trials (RCT) and non-RCT studies that focused on prescribing interventions of nurses and pharmacist was also conducted to explore the impact of their prescribing interventions in treating type 2 diabetes using HbA1c level as the primary outcome. A programme of work of three retrospective comparative database analytical studies was then carried out to investigate the impact of independent NMPs in type 2 diabetes care. This programme of work used electronic medical records of patients attending outpatient clinics of diabetes centres in two teaching hospitals in Manchester; one employed an independent pharmacist and the other employed DSN prescribers. A group of subjects seen by an NMP in place of a doctor during the study period were the study group and the control group were those who seen only by doctors. The primary outcome was the average yearly change of HbA1c amongst the two groups. Secondary outcomes were yearly change of total cholesterol, blood pressure and serum creatinine as well as body mass index. Five statistical models, which included multivariable regression, propensity score matching and sensitivity analyses, were utilised to control for confounding effects, and the nature of selection bias in the retrospectively comparative effectiveness research using secondary database resources. A total of 330 patients seen by a team including a pharmacist versus 975 by doctors only between January 2006 and January 2013 at one site; and 656 by a team including DSNs versus 3,746 patients seen by doctors only between January 2007 to December 2013 at the other. The studies found both prescribing pharmacists and DSNs are capable of achieving at least non-inferior improvements in diabetes outcome compared to doctors. The pharmacist achieved a mean 0.01% reduction in HbA1c level versus doctors who achieved slight increase (p<0.4). DSNs also achieved a mean 0.07% reduction compared to doctors. However, after adjustment with multivariate and propensity score as well as with propensity score matching, there were no significant differences between the two groups. These findings were consistent with the findings in the systemic review. Although an RCT is the only method that by definition would produce unbiased treatment effects, the use of propensity score methods here, have reduced the potential for bias that may remain unaccounted for in multivariate models without propensity scores. Adjusting for propensity scores using two different methods also gives more confidence that the results are as unbiased as possible. Nonetheless, caution in generalising the results is necessary because of the retrospective nature of the studies and deficiencies in the database used.

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Keyword(s)

Comparative Effectiveness Research; Diabetes Mellitus; Non-Medical Prescribers; Non-Medical Prescribing; Nurse Prescribing; Pharmacist Prescribing; Propensity Score Matching; Type 2 Diabetes

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