How complete are drug history profiles that are based on public drug benefit claims?

BACKGROUND: In Canada, programs are being developed to supply hospital emergency departments and family doctors with electronic access to their patientsâ drug history profiles. While some of these programs have access to databases that capture information about all out-patient prescriptions that are dispensed to an individual, regardless of payer; others do not, and rely upon claims paid by their provincial drug benefit plans. The completeness of these latter profiles is unknown. OBJECTIVES: To estimate the percentage of Ontario seniors who use private drug insurance (as an indicator of the potential for a âpublicâ drug history profile to be incomplete) and to describe the kinds of medications for which private insurance is used. METHODS: Cross-sectional time series analysis of Ontario Drug Benefit (ODB) claims and private drug insurance claims for Ontario residents aged 65 years or older (seniors) covering the period January 2000 to December 2005. RESULTS: During the study period, approximately 95% of Ontario seniors filled at least one prescription paid by the provincial drug benefit plan. By comparison, approximately 15-20% filled a prescription paid by a private insurer. Compared to the 20 drugs most frequently subsidized by the ODB Program (all but one of which had ODB full benefit status), the top privately-purchased drugs were more diverse: 8 had ODB full benefit status; 4 had ODB Limited Use status (which requires that patients meet prespecified clinical criteria for coverage); 3 required individual clinical review (prior authorization) by the ODB Program; and 5 were ODB non-benefits. CONCLUSIONS: Many Ontario seniors are at risk for an incomplete ODB drug history profile. Further research is needed to confirm whether this causes problems for physicians and patients.