Three months versus 28 day prescriptions: a retrospective analysis of CPRD data to determine differences in the cost of drug wastage, dispensing fees and prescriber time

Date of ISAC Approval: 
21/06/2016
Lay Summary: 
In the NHS, general practitioners (GPs) have been encouraged to issue prescriptions of shorter duration (e.g., 28 days), to reduce drug expenditure and wastage. There is, however, the potential for shorter prescriptions to increase costs through increased GP workload and dispensing fees. Currently, the consequences of longer and shorter prescriptions for patients with chronic diseases are unknown and need to be assessed. The purpose of this study is to determine if there are differences in the costs related to drug wastage, dispensing fees and prescriber time as a result of early refills and treatment switches for prescriptions issued as either a 28-day or 3-month supply in five selected case study scenarios representing common chronic conditions. This study will provide important information to the Department of Health in understanding the impact that encouraging GPs to issue shorter supplies of drugs has had on drug expenditure and drug wastage and additionally, help inform future prescribing policies.
Technical Summary: 
The aim of this study is to estimate the differences in the costs of drug wastage, dispensing fees and prescriber time as a result of early refills and treatment switches in patients receiving medications as either 28-day or 3-month supplies for a number of common chronic diseases. A retrospective cohort analysis will be conducted using data from a random sample of 50,000 patients for five case study conditions derived from all adult patients receiving at least one prescription relevant to the respective condition during the 10-year period between 2004 and 2014. The volume of wastage from early refills and treatment switches (defined as a repeat prescription or new prescription for a drug commonly prescribed for the same condition being issued prior to the expiry of the previously prescribed quantity) will be estimated. Unit costs from standard sources will be applied to estimate the cost of wastage and dispensing for a common price year. The cost of health professional time to issue the prescription will also be added. Changes in drug wastage and dispensing fees will then be estimated had all prescriptions been for 28 days rather than the observed length.
Health Outcomes to be Measured: 
The five case study conditions are: 1) glucose control in type II diabetes (patients receiving at least one prescription for an anti-diabetic drug listed under ?BNF 6.1.2 Antidiabetic drugs?); 2) primary prevention of hypertension in type II diabetes (in addition to receiving an anti-diabetic drug as defined in (1), patients receiving at least one prescription for a medication used for the primary prevention of hypertension in type II diabetes patients, including angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, calcium-channel blockers and thiazide-like diuretics); 3) primary prevention of hyperlipidaemia in type II diabetes (in addition to receiving an anti-diabetic drug as defined in (1), patients receiving at least one prescription for a statin used for the primary prevention of hyperlipidaemia in type II diabetes patients; 4) secondary prevention of myocardial infraction (in addition to receiving concurrent prescriptions for a angiotensin-converting enzyme inhibitor, antiplatelet and statin for at least one year in duration, patients may also receive prescriptions for beta-adrenoceptor blockers, calcium-channel blockers, oral anticoagulants and aldosterone antagonists); 5) depression (patients receiving at least one prescription for an anti-depressant drug listed under BNF 4.3 Antidepressant drugs).
Collaborators: 

Edward Wilson - Chief Investigator - University Of Cambridge
Brett Doble - Corresponding Applicant - University Of Cambridge
Dr Rupert Payne - Collaborator - University of Bristol
Sarah King - Collaborator - University Of Cambridge