The Danish National Prescription Registry in studies of a biological pharmaceutical: palivizumab - validation against two external data sources.

Background: National prescription databases are important tools in pharmacoepidemiological studies investigating potential long-term adverse events after drug use. Palivizumab is a biological pharmaceutical used as passive prophylaxis against severe infection with respiratory syncytial virus in high-risk children.

Objective: To assess the registration of palivizumab in the Danish National Prescription Registry (DNPR) and to examine if palivizumab reimbursement data obtained from the Danish Health and Medicines Authority could serve as a supplement to data from the DNPR.

Methods: Registration of palivizumab exposure in the DNPR between 1999 and 2010 was compared to two external data sources: registration of palivizumab exposure in medical records, and palivizumab reimbursement data.

Results: During the study period, 182 children with palivizumab exposure were registered in the DNPR. A total of 207 children were registered for palivizumab reimbursement. The sensitivity of palivizumab registration in the DNPR was 26% (20%-34%), and the specificity of no palivizumab registration in the DNPR was 97% (94%-99%), with data from the medical record as the reference. Palivizumab registration sensitivity in reimbursement data was 29% (22%-36%), and the specificity of no palivizumab registration in the DNPR was 97% (94%-99%), with data from the medical record as the reference.

Conclusion: Exposure to palivizumab was underestimated in the DNPR. Reimbursement data are a readily accessible data supplement, which only slightly increased the sensitivity of palivizumab registration in the DNPR. Our findings underline the need to improve DNPR information concerning drugs administered in hospitals.