Analysis of medical consultation interval between the symptom onset and consultation observed in multiple medical facilities in Odate city, Japan, 2011/2012 and 2012/2013 seasons

Background: Influenza remains one of the most important causes of respiratory infection despite the widespread availability of vaccines. Anti-influenza viral agents such as neuraminidase inhibitors are generally efficacious in alleviating the symptoms if they are administered within 2 days of the illness onset. However, few studies have examined the situation of interval between illness onset and medical consultation in influenza outpatients on community level. And the predictors or determinants for longer medical consultation interval have not been well-defined. Material and method: An enhanced surveillance study was conducted in Odate city of Japan in 2 consecutive seasons from 2011 to 2013. The late consultation rate (>2 days) and its risk factors were investigated in confirmed influenza outpatients. Results: A proportion of 5.5% of patients visited doctors beyond 2 days of illness onset. Illness onset during non-high-incidence period, infection with influenza B and being adult or elderly were identified as independent risk factors for late consultation and the risk increased with the number of risk factors. Conclusion: The consultation behavior for influenza was generally well in our study population. Identified risk factors should be addressed in health education and promotion for the late consultation.