Clinical information relating to all morbidity and drug therapies is recorded using standard classifications of Read codes [ 39] and BNF (British National Formulary) respectively [ 40].
Prescriptions are recorded by using Multilex (www.fdbhealth.co.uk/solutions/multilex) drug codes, which link each drug formulation to the British National Formulary, a compendium of drugs arranged by system into 15 chapters.
The amount of opioid analgesia used in the 24 hours following catheter removal was also recorded from the patient's drug prescription card and converted to intravenous morphine equivalent using the British National Formulary standard conversion ratios [ 17].
In order for their bills to be settled by the Pharmacy Service, pharmacists must use the computerized data-collection system to record the details of the prescribed drug (national drug formulary code), those of the prescribing doctor (health area identification code and registration number) and those of the patient for whom the drug is prescribed (personal identification code), among others.
When a generic supply of medication is introduced into the in-house pharmacy inventory, administrative staff may not code new identifier records in the formulary that are specific to the generic.
Additional covariates in this analysis were the Townsend deprivation score for the practice postcode (in national quintiles; H-C&C used quintiles of patient-level Townsend scores) and use of β-blockers, aspirin, ACE inhibitors and calcium channel blockers, identified through the British National Formulary 32 chapter codes in the patient record.
25 The Ontario Drug Benefit database contains records of all outpatient prescriptions for formulary drugs dispensed to patients aged 65 years or older and has an error rate of less than 1%. 25 26 The Canadian Institute for Health Information discharge abstract database provides detailed information on all hospital admissions in Ontario.
11 The database also includes records of all prescriptions issued and these are linked to the British National Formulary (BNF).
For this reason, formulary committees have been conservative in their adoption of new fluoroquinolones until a proven track record has been established.
The use of such aids as personal digital assistants (PDAs), computerized physician order entry (CPOE), electronic health records (EHRs), and electronic databases has shown positive influence on patient morbidity and mortality, cost management and formulary compliance, and prevention of medication errors and related fatalities [ 3, 7- 13].
