[Validity in estimating influenza patient numbers from National Epidemiological Survey of Infectious Diseases (NESID) data using Oseltamivir consumption in Hyogo Prefecture].

The National Epidemiological Surveillance of Infectious Diseases (NESID) estimates the number of influenza patients using sentinel medical institutions reports (NESID estimate) rather than the actual number of patients visiting medical institutions. We estimated Hyogo Prefecture influenza patient numbers using Oseltamivir consumption (Oseltamivir estimate) to determine NESID estimate validity for the Nov-May, 2003-2007 influenza seasons. We divided the seasonal Oseltamivir estimate by the NESID estimate to derive an estimated prescription rate assuming that the NESID estimate was accurate. Estimated prescription rates ranged from 50% to 100%, but the NESID estimate assumption is appropriate from the relationship between the estimated prescription rate and prescription status. In 2004-2005 and 2005-2006 years 94% and 100% for the estimated prescription rate were close to the results (90%) from nationwide Oseltamivir prescription investigation. Nationwide analysis and investigations needed in other seasons on prescription rate of influenza medicine (Oseltamivir, Zanamivir, etc.) are thus needed for generalization on the validity of "NESID estimate".