8.3 Literature Exercise

Locate Article

This exercise will be based on a research article with the following citation:

A Randomized, Controlled Trial in Children to Assess the Immunogenicity
and Safety of a Thimerosal-free Trivalent Seasonal Influenza Vaccine (2012).
Domachowske, JB et al., The Pediatric Infectious Disease Journal 31(6): 605.

Locate the article online, read through it, and answer the questions below.

8.3.1 Critical Reading

The study examines a thimerosal-free vaccine, where thimerosal is a mercury-containing compound that is hypothesized to increase risk of autism.

1. What was the primary objective of the study?
   • To show that thimerosal in vaccines leads to increased risk of autism
   • To show that a thimerosal-free vaccine is noninferior compared to an existing vaccine
   • To show that a thimerosal-free vaccine has superior performance to an existing vaccine
2. What was the explanatory variable and its treatment/factor levels?
   • Vaccine amount (varying dosage levels)
   • Age of vaccination (three age groups)
   • Vaccine type (thimerosal-free vs. existing with thimerosal)
3. Was a control used? If so, what is the control?
   • Yes, the control was a placebo
   • Yes, the control was the existing vaccine
   • No, there was no control
4. What was the response variable?
   • Adjusted geometric mean titer
   • Autism rates
   • Successful vs. unsuccessful immunization
5. Is the response variable a continuous or categorical variable?
   • categorical
   • continuous
   • neither
6. Who were the subjects in the study?
   • 2116 children between ages 3 and 17
   • 2116 adults aged 18 and older
   • 2100 children between ages 6 and 35 months
7. Was the study balanced?
   • It was perfectly balanced
   • It was close to balanced
   • It was very imbalanced
8. Did the study incorporate blinding? If so, which type of blinding?
   • No, the study did not incorporate blinding
   • Yes, the study blinded the participant (vaccine recipient) only
   • Yes, the study blinded both participants and the study researchers (“double blind”)
9. Did the study incorporate blocking? If so, what are the blocking variables?
   • Yes, they blocked by age, center, prior immunization, and intent to immunize
   • Yes, they only blocked by age
   • No, they did not incorporate blocking
10. Was there randomization?
    • Yes
    • No
    • They don’t say
11. What kind of study was it?
    • Case Control Study
    • Observational Study
    • Randomized Control Clinical Trial
12. In causal inference notation, what type of study is it?

    • Randomized Control Posttest

      R X O1
      R _ O2

    • Randomized Control Pretest-Posttest

      R O1 X O2
      R O3 _ O4

    • Soloman 4 Group Design

      R O1 X O2
      R O3 _ O4
      R    X O5
      R    _ O6

13. What can you conclude from this study?
    • The study vaccine causes more harm than the existing vaccine
    • The study vaccine is superior to the existing vaccine
    • The study vaccine is no worse than the existing vaccine
    • The study results were ambiguous