Appropriateness of antiviral prescribing for influenza in primary care: a retrospective analysis*

BACKGROUND AND OBJECTIVE: Antiviral medications cost-effectively reduce influenza-related morbidity and potentially mortality. We sought to assess the appropriateness of antiviral prescribing for influenza. METHOD: We performed a retrospective analysis of visits by adults to primary care clinics during influenza seasons from 1 October 2000 to 31 May 2004 with a claims diagnosis of influenza (n=535) or with an electronic antiviral prescription (n=25). We defined appropriate antiviral prescribing as the patient having (a) symptoms for 2 or fewer days, (b) fever and (c) any two of headache, sore throat, cough, or myalgias. RESULTS AND DISCUSSION: Physicians diagnosed patients with influenza in 102 of 535 (19%) visits with a claims diagnosis of influenza. Physicians prescribed antivirals at 15 of 102 (15%) of these visits. The addition of 25 additional electronic antiviral prescriptions gave a sample of 127 visits and 40 (31%) antiviral prescriptions. Twenty-eight (70%) antiviral prescriptions were appropriate. Among patients who did not receive antivirals, 21 of 87 (24%) met criteria for appropriate antiviral prescribing. Antiviral prescribing was associated with a shorter median symptom duration (2 days vs. 3 days; P<0.01) and higher median temperature (37.8 degrees C vs. 36.9 degrees C; P<0.01). Physicians prescribed antivirals more frequently to patients who had myalgias (37% vs. 18%; P=0.04) and an influenza test (67% vs. 28%; P<0.01). Physicians prescribed antivirals more frequently to Blacks (44%) and patients with other race/ethnicity (67%) than to Whites (20%) or Hispanics (20%; P<0.0001). CONCLUSIONS: To improve antiviral prescribing for influenza in primary care, interventions need to target the accurate identification of influenza visits, undertreatment, as well as inappropriate treatment.