An Evaluation of Influenza Mortality Surveillance, 1962–1979: Ii. Percentage of Pneumonia and Influenza Deaths as an Indicator of Influenza Activity

Choi, K. (Bureau of Epidemiology, CDC, Atlanta, GA 30333), and S. B. Thacker. An evaluation of influenza mortality surveillance, 1962–1979. II. Percentage of pneumonia and Influenza deaths as an indicator of influenza activity. Am J Epidemiol 1981;113:227–35. In this paper, the percentage of all deaths that are related to pneumonia and influenza (P & I ratio) is evaluated as an indicator of influenza activity and as a method to quantify the impact of influenza on mortality. Analysis of data from 1962–1979 Indicates that the P & I ratio is an accurate indicator of influenza activity, as confirmed by independent systems of morbidity and laboratory surveillance. A rule using the P & I ratio for detecting an outbreak of an influenza epidemic was evaluated. It was found to be much more specific than a rule based on the regression model, but did not provide more timely detection of outbreaks of influenza during the past 17 years. The use of the P & I ratio in the autoregressive integrated moving average (ARIMA) model of forecasting provided the most accurate prediction of the expected pneumonia and influenza mortality.