Surveillance of outpatient antibiotic consumption in Spain according to sales data and reimbursement data

Objectives: National data on antibiotic consumption are needed in order to interpret trends in antibiotic resistance. We compared antibiotic prescription reimbursement data and sales data in Spain. Methods: Data covering the years 2002, 2004 and 2005 were examined. Reimbursement data for ambulatory care were provided by the Spanish Agency for Medicines and Healthcare Products and sales data by International Medical Statistics Health. Quantities were standardized using the defined daily dose per 1000 inhabitants per day (DID) in accordance with the anatomical therapeutic classification. Results: Sales data increased from 26.33 DID in 2002 to 28.12 DID in 2004 and 28.93 DID in 2005. Estimates based on equivalent reimbursement data were similar to 30% lower and increased from 18.01 DID in 2002 to 18.48 DID in 2004 and 19.29 DID in 2005. The differences were greatest for amoxicillin, amoxicillin/clavulanic acid, clarithromycin and cefuroxime. Conclusions: Antibiotic consumption as estimated from reimbursement data is substantially less than that from sales data. This finding has major implications for national surveillance of antibiotic consumption.