Influenza associated excess mortality in Germany, 1985-2001

Area of Science:

• Epidemiology
• Public Health
• Biostatistics

Background:

• Influenza-associated excess mortality is a key indicator for assessing epidemic severity.
• This metric is not yet routinely integrated into German influenza surveillance systems.
• Accurate estimation is crucial for public health preparedness.

Purpose of the Study:

• To apply and evaluate the relative mortality distribution method (RMDM) for estimating influenza-associated excess mortality in Germany.
• To compare RMDM with cyclical regression for influenza surveillance.
• To analyze trends in excess mortality from 1985-2001.

Main Methods:

• Utilized a time-series of German monthly all-cause mortality data (1985-2001).
• Applied the relative mortality distribution method (RMDM) to estimate excess deaths.
• Compared RMDM results with those from cyclical regression analysis.

Main Results:

• RMDM demonstrated a better fit (R2 = 0.80) compared to cyclical regression for distinguishing influenza seasons.
• Estimated average excess deaths per season between 6,900 (conservative) and 13,600 (crude) for 1990/91-2000/01.
• Most severe epidemics were associated with influenza A/H3N2 subtype.
• Observed an upward trend in excess deaths despite declining overall mortality, linked to an aging population.

Conclusions:

• RMDM is a suitable method for estimating influenza-associated excess mortality in Germany.
• Findings highlight the significant burden of influenza, especially in vulnerable elderly populations.
• The study underscores the need to incorporate excess mortality estimation into routine German influenza surveillance.