Is immunising all patients with chronic lung disease in the community against influenza cost eVective? Evidence from a general practice based clinical prospective cohort study in Utrecht, the Netherlands

Study objective—There is little information on the potential benefit of immunising all patients with chronic lung disease in the community against influenza. The clinical eVectiveness and economic benefit was established of the influenza vaccination programme in a general practice based cohort of adult patients with chronic lung disease followed up during the 1995/96 influenza A epidemic. Design—A prospective cohort study from October 1995 to March 1996. Setting—The study was undertaken in the Utrecht General Practices Network with six large group practices, covering a total population of approximately 50 000 patients in the Netherlands. Patients—Computerised medical records of 1696 patients with chronic lung disease aged over 18 years with an indication for vaccination according to the Dutch GP guidelines were reviewed. Main results—The overall attack rate of any complication, including all cause death, low respiratory tract infection, and acute cardiac disease was 15%. Exacerbations of lung disease were most frequent (13%). Death, pneumonia, and acute cardiac disease were mainly limited to patients >65 years. No eVectiveness of the immunisation programme could be established in patients 18–64 years (n=1066), after controlling for baseline prognosis in multivariable logistic regression analysis. In vaccinees>65 years (n=630), the occurrence of any complication was reduced by 50% (95% CI 17, 70%). The economic benefit was estimated at £50 per elderly vaccinee. Conclusions—This study suggests that in the Netherlands immunisation of elderly patients with chronic lung disease against influenza is eVective and cost-saving, hence these patients should be given high priority. More, preferably experimental, studies are needed to establish whether adult lung patients under 65 years in the community will also benefit from vaccination. (J Epidemiol Community Health 1998;52:120–125) Although annual influenza vaccination has been recommended to all patients with chronic pulmonary disease, immunisation rates remain low, particularly in patients under 65. These low rates may only be partly the result of concerns about side eVects, because many studies have shown no serious adverse events. Scepticism about the impact of influenza in non-institutionalised patients with chronic lung disease is more likely to play an important part. Currently, little information is available on influenza related mortality and morbidity in this group. Several studies have reported on the eVectiveness of influenza vaccination, but most were confined to elderly subjects with or without chronic medical conditions. Only a few studies included younger adults, and none considered the eVectiveness in patients with chronic lung disease alone. This apparent lack of evidence of the potential health and economic benefit resulting from immunising all patients with chronic lung disease in the community against influenza may explain the poor immunisation rates. 20 We aimed to assess the clinical eVectiveness of an influenza vaccination programme in preventing complications in adult patients with chronic pulmonary disease. We therefore prospectively followed up a general practice based cohort of patients with lung disease from the moment of vaccination until the end of the influenza A epidemic of 1995/96. Because an age based immunisation policy was recently introduced in the Netherlands, after many other countries, we considered its eVectiveness in patients aged under and those aged over 65 years. Finally, we estimated direct costs of medical care associated with the influenza epidemic and immunisation programme.