DBecker1988

Here is the study: Evidence of bias in estimates of influenza vaccine effectiveness in seniors The authors hypothesis is that those who get the influenza vaccination are more likely to be heath conscious individuals which might account for lower incidence of infection. I.E. healthy elders are motivated to be healthy and make healthy choices such as eating right, exercising, and getting their yearly vaccination. From this notion the author hypothesis that the main reason they are less likely to get sick is not from the vaccination, but rather from the other measures these people are taking to be healthy (exercise and diet) Thats all fine and dandy in theory, but I am having some issues interpreting how the results of the authors statistical analysis correlates with the conclusions. Perhaps someone who is more statistically inclined than myself can help by explaining the meaning of the results: Results: The relative risk of death for vaccinated persons compared with unvaccinated persons was 0.39 [95% confidence interval (95% CI), 0.33–0.47] before influenza season, 0.56 (0.52–0.61) during influenza season, and 0.74 (0.67–0.80) after influenza season. The relative risk of pneumonia hospitalization was 0.72 (0.59–0.89) before, 0.82 (0.75–0.89) during, and 0.95 (0.85–1.07) after influenza season. Adjustment for diagnosis code variables resulted in estimates that were further from the null, in all time periods. What is the meaning of the numbers 0.39, 0.56, 0.72 etc.? How did these numbers come to be? Lastly, what does it mean that they consistently show the tendency to approach 1 with the progression of time? (see also table 5 on page 342) One other confusing issue: Why is it that "healthy individuals" represent a demographic with more comorbidities? Isn't the reverse true? Perhaps I'm misinterpreting the data.