Accuracy of a Prescription Claims Database: METHODS

12 Nov
2010

This cross-sectional cohort study evaluated agreement between medication lists obtained from a structured patient interview and from the PharmaNet profile available to British Columbia hospital pharmacists. This profile includes, in one comprehensive list, all active and inactive prescription medications filled at British Columbia community pharmacies during the previous 14 months, excluding drugs used to treat HIV (for historical reasons related to confidentiality). A cohort of patients with heart failure was selected as the study sample because these patients typically have a large number of similar prescription medications, and these complicated drug regimens often prompt hospital pharmacists to review PharmaNet for medication history information. All patients with current contact information who had an appointment at the St Paul’s Hospital Heart Function Clinic or the Pre Heart Transplant Clinic between January and August 2003 were contacted by regular mail with an invitation to participate. Patients with active prescriptions for furosemide and an angiotensin- converting enzyme (ACE) inhibitor or an angiotensin receptor blocker were also recruited from 3 local community pharmacies. A consent form describing the study methods was reviewed with all patients who expressed an interest in participating. Consenting patients were asked to go to St Paul’s Hospital for a 30- to 60-min interview and to bring with them all medications that they were currently consuming. The interviews were carried out by a pharmacy resident (L Jang) or an undergraduate pharmacy student trained by the principal investigator (S Salansky) and were based on a structured survey instrument developed for this study. The survey was pretested with clinic patients and was revised according to feedback to ensure that the wording of each question was clear. During the interview, responses to survey questions, medication labels, printed PharmaNet profiles, and clinic records (for clinic patients only) were reviewed with the goal of obtaining an accurate list of currently consumed, regularly administered prescription medi­cations, including doses and dosing frequencies. Although information on use of nonprescription and alternative medicines was collected, these medications were not included in the medication lists used for analysis of agreement, because PharmaNet records only medications issued by prescription. Discrepancies between the medication lists obtained from the patient and from PharmaNet were queried, and a consensus regarding current medication consumption was reached between the interviewer and patient. When provided by the patient, reasons for discrepancies between the consensus list and the PharmaNet profile were recorded. In addition to use of a checklist, patients were encouraged to provide additional comments, which were categorized during the data analysis. canada drugs pharmacy

To evaluate agreement between the medication lists obtained from PharmaNet and the patient interview, a consistent definition of “active” (i.e., currently consumed) medications was used for all medication lists obtained. Medications were deemed active according to the PharmaNet profile if the most recently dispensed supply provided a sufficient quantity to last at least until the date of the interview if taken according to the prescription directions. Accordingly, medications were excluded from the agreement analysis if it was not possible to determine, from refill data listed in PharmaNet, whether they were currently active. For example, liquids and creams were excluded, as were medications for which PharmaNet directions indicated that the drug was to be taken “as needed” or “as directed”. Warfarin was also excluded from the analysis, because doses of this drug commonly fluctuate between refills. Medications mentioned during the interview were considered active if the patient indicated that he or she was using them regularly up to and including the day of the interview. Medications excluded from the PharmaNet list were also excluded from the interview list. However, if a medication was to be used “as needed” (prn) according to the PharmaNet profile but the patient claimed to be using it on a regular schedule, the medication was included on the interview list for the purpose of agreement analysis.

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