Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004
Author Information
Author(s): Nunes Baltazar, Viboud Cecile, Machado Ausenda, Ringholz Corinne, Rebelo-de-Andrade Helena, Nogueira Paulo, Miller Mark
Primary Institution: Instituto Nacional de Saúde Dr Ricardo Jorge, Lisbon, Portugal
Hypothesis
What is the excess mortality rate associated with influenza virus circulation in Portugal during the period of 1980–2004?
Conclusion
Influenza epidemics in Portugal resulted in an average of 2,475 excess all-cause deaths each winter from 1980 to 2004, primarily affecting seniors over 65 years.
Supporting Evidence
- Influenza was associated with a seasonal average of 24.7 all-cause excess deaths per 100,000 inhabitants.
- 90% of excess deaths occurred in individuals aged 65 years and older.
- Excess mortality rates were highly correlated with seasonal rates of influenza-like illness among seniors.
Takeaway
When people get the flu, more of them die than usual, especially older folks. In Portugal, a lot of extra deaths happened during flu seasons from 1980 to 2004.
Methodology
The study used ARIMA models to analyze monthly mortality data by age and cause of death, comparing observed deaths during influenza epidemic periods to expected deaths.
Potential Biases
Potential biases may arise from the reliance on mortality coding practices and the definition of epidemic periods.
Limitations
The study relies on statistical models that may have assumptions affecting the accuracy of excess mortality estimates.
Participant Demographics
The study focused on the Portuguese population, particularly seniors aged 65 and older.
Statistical Information
P-Value
p<0.001
Confidence Interval
95% CI
Statistical Significance
p<0.001
Digital Object Identifier (DOI)
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