Assessment of the Prescriber's and the Pharmacies Overview of Patient Medication by Use of the Fidelity Coefficient.

The fidelity coefficient, FC, is a measure of what proportion of individual patients' medication that are accounted for by the most used prescriber and the most used pharmacy. Each patient therefore has two values, one describing his fidelity towards his most used prescriber, FCPresc, and one describing his fidelity towards his most used pharmacy, FCPharm.

The investigators intend to assess this parameter in an observational population scale database study, using standard descriptive statistics, and subsequently compare the obtained average FCPresc and FCPharm.

Furthermore, the investigators will analyze the two obtained FCs for dependency of a predefined list of variables: age, gender, number of prescriptions, whether the most frequent prescriber was a GP and whether the most used pharmacy was urban.

Finally, the investigators intend to analyze which medications (grouped using the ATC-system with 4 digits, e.g. C07A) that has the highest proportion of prescriptions that were either issued by a non-main prescriber or redeemed at a non-main pharmacy, which roughly translates into the most 'infidel' medications. To insure relevance we intend to use a cut-off-value of the medication being prescribed at least 50.000 times, which equals about 85 % of the data according to preceding analyses.

The data for this study will be obtained from the Odense University Pharmacoepidemiological Database (OPED). In brief, it is a research database with full coverage of all reimbursed prescriptions in the Region of Southern Denmark (1.2 million inhabitants). The data included in each prescription record includes the prescription holder, the prescriber, the pharmacy, the date of dispensing and a full account of the dispensed product, including substance, brand name, route of administration, ATC-code and Defined Daily Dose (DDD).

Some drugs are exempt from re-imbursement and thus not covered by the database, including benzodiazepines, oral contraceptives, laxatives and certain antibiotics.

Inclusion criteria

• Having filed more than 9 prescriptions during 2009.

Exclusion criteria

• None