Dr Tristan Clark is associate professor in infectious diseases at the University of Southampton. Here he gives an update on neuroaminidase inhibitor use in older people, and invites readers to participate in a new survey of practice.
Influenza causes excess hospitalisations and 10,000 excess deaths every year in the UK and most of this burden falls on the elderly. Although the rate of hospitalisation in adults with influenza is 5-20 per 100,000 it is 1200 per 100,000 in those over 85 years old. Once hospitalised with influenza, 10-30% of adults are admitted to critical care units and 3-15% will die. Influenza vaccine uptake remains sub-optimal in the over 65s with only 70% accepting vaccination. Furthermore, whilst influenza vaccination is highly effective in healthy younger adults, protection decrease with age and high quality evidence for significant protection in the elderly is lacking.
The neuraminidase inhibitors (NAIs) Oseltamivir and Zanamivir are recommended by UK guidelines for treatment of adult patients with influenza during periods of peak seasonal activity. Over the past few years there has been much controversy regarding the evidence for these drugs following a Cochrane review, partly related to unpublished pharma-sponsored trial data. In addition there have been no high quality randomised controlled trials evaluating NAIs in hospitalised adults although recently published observational data suggests that they may reduce mortality in this group.
Current UK practise involves testing patients for influenza based on clinical suspicion, which is inaccurate, even during peak periods of influenza activity. Patients suspected of having influenza are treated empirically with NAIs whilst awaiting the results of laboratory testing because of the prolonged turnaround times of laboratory PCR. This means that many patients who turn out not to have influenza are treated unnecessary with NAIs with the associated risk of side effects.
Physician concordance with guidelines for NAI prescribing is poor in the other countries including the US, however no studies have been conducted here. Studies examining NAI use in hospitalised adults are needed to define current practice and frame the future research agenda including trials of antivirals.
Because the majority of hospitalised adults with influenza are elderly, hospital geriatricians represent a key group of physicians involved in the assessment and care of patients with suspected and confirmed influenza. As such their prescribing practices and opinions regarding NAI’s use are of huge importance. Together with other groups of physicians (respiratory physicians, infection specialists, emergency physicians and acute physicians), we are asking geriatricians to take part in our electronic survey of practice. We hope that the result of this survey will ultimately help to improve the care of patients with influenza.