Salk Vaccine Field Trial

Pfizer’s Sildenafil Citrate Trials 1995-1997

Attempts to Eliminate Confounding?

Yes, control group was chosen from the same population as the treatment group (p.5 paragraph starts with "Many public health")

Type of Assignment

Randomized controlled. An impartial chance procedure was used to assign subjects (p. 5 paragraph starts with "Experience shows")

Placebo (blinding)?

Yes. Control group was given a saline injection (p. 5 paragraph starts with "Another basic")

Double Blinding?

Yes. Doctors were not told which group the subject belonged to. (p. 5 same paragraph as placebo)

Replication?

Yes, in a way. The Salk Vaccine Field Trial was an improvement over the NFIP design (see Table 1)

Outcomes

Rate of polio cases for each group

Treatment: 28 per 100,000

Control: 71 per 100,000

No Consent: 46 per 100,000