Presentation with influenza-like illness in general practice: implications for use of neuraminidase inhibitors.

General practitioners in the Midlands Research Practice Consortium (MidReC), combined list size 140,000, completed questionnaires about 918 patients in whom they had made working diagnoses of influenza-like illness during an outbreak of influenza A H3N2 from 1 December 1999 to 4 February 2000. Adults, more females than males consulted most, reflecting the age and sex distribution reported to the Royal College of General Practitioners Weekly Returns Service. Illness at presentation was considered severe in 4%, moderately severe in 49%, mild in 45%, and asymptomatic (for example, attended for certificates) in 1% of patients. In seven tenths of patients, the practitioner estimated that the likelihood of influenza was 70% or more and in just over half, 80% or more. Half of patients aged over 75 years were seen at home, but only 7% of those under 55 years. Less than a quarter of patients consulted within two days of having become ill, with the highest consultation frequency on the third and fourth days. Preschool children presented earliest: 75% were seen within two days, compared with only 17% of adults over 75 years. Four fifths of patients were seen on the same day as they contacted the practice, and 12% on the following day. Given the brief time window for effective antiviral treatment, only a small proportion of patients are likely to be prescribed these drugs unless consulting behaviour, especially in elderly people, changes considerably.