Prescription of antiviral drugs during the 2009 influenza pandemic: an observational study using electronic medical files of general practitioners in the Netherlands

Background: After the clinical impact of the A(H1N1) pdm09 virus was considered to be mild, treatment with antiviral drugs was recommended only to patients who were at risk for severe disease or who had a complicated course of influenza. We investigated to what extent antiviral prescriptions in primary care practices were in accordance with the recommendations, what proportion of patients diagnosed with influenza had been prescribed antiviral drugs, and to what extent prescriptions related to the stated indications for antiviral treatment. Methods: We used data from routine electronic medical records of practices participating in the Netherlands Information Network of General Practice LINH in the period August -December 2009. We considered patient and practice characteristics, clinical diagnoses and drug prescriptions of all patients who contacted their general practitioner in the given period and who had been prescribed antiviral medication (n = 351) or were diagnosed with influenza (n = 3293). Results: Of all antiviral prescriptions, 69% were in accordance with the recommendations. Only 5% of patients diagnosed with influenza were prescribed antiviral drugs. This percentage increased to 12% among influenza patients belonging to the designated high risk groups. On the other hand, 2.5% of influenza patients not at high risk of complications received antiviral treatment. In addition to the established high risk factors, the total number of drug prescriptions for a patient in this year was a determinant of antiviral prescriptions. Information on time since onset of symptoms and the clinical presentation of patients was not available. Conclusions: General practitioners in the Netherlands have been restrictive in prescribing antiviral drugs during the influenza pandemic, even when patients met the criteria for antiviral treatment.