The November 17, 1994 issue of The New England Medical Journal reported on a study of the effects of hormone therapy on middle-aged women. About 750 women took part in the study; half were selected randomly to receive the hormone therapy, and the other half were given a placebo (they did not know which). After about a year, blood tests were conducted on each subject by a lab technician who was unaware of which group (treatment or placebo) the blood samples originated from. In presenting the results of the experiment, the authors reported that the women in the treatment group had experienced a statistically significant increase in HDL (the so-called "good" cholesterol) and a statistically significant reduction in LDL (the so-called "bad" cholesterol) when compared with the control group.

What type of design is this study?

1) This is an example of a block design.
2) This is an example of a completely randomized design.
3) This is an example of a matched pairs design.
4) This study would be classified as un-blinded.
5) This study would be classified as single-blinded.
6) This study would be classified as double-blind.

The described study is an example of a double-blind design where neither participants nor researchers are aware of the treatment assignments. Hormone therapy has complex effects on health, and while early studies suggested it may protect against heart disease, subsequent randomized controlled trials indicated it may not prevent it and could have negative health outcomes. Therefore, the option (6) This study would be classified as double-blind., is the correct answer

Explanation:

The study described in the question is an example of a double-blind design. In this type of randomised controlled trial (RCT), neither the participants nor the researchers know who is receiving the treatment or the placebo, which helps prevent bias and ensures the validity of the research results. The involvement of a lab technician who is unaware of the participants' group assignments reinforces the double-blind nature of the study.

Regarding hormone therapy (HT), while it has been used to alleviate menopausal symptoms, its effect on health outcomes such as cardiovascular disease and breast cancer risk has been a subject of intense debate and study. Early observational studies suggested a protective effect against heart disease, but later RCTs showed that hormone replacement may not prevent heart disease and, in some cases, is associated with negative health outcomes. However, more recent research suggests potential cardiovascular benefits and no increased risk for cancer with estrogen use, though this remains controversial and further research is needed to fully understand the benefits and risks of HT.Therefore, the option (6) This study would be classified as double-blind., is the correct answer