Question

Researchers conducting a clinical trial randomly assigned 60 patients with painful knee osteoarthritis evenly into one of three treatment groups: glucosamine, chondroitin, or placebo.After the study period, patients were asked if they experienced substantial improvement in pain and ability to function normally.Thirty-four patients replied that they did have an improvement, including 13 in the glucosamine group, 16 in the chondroitin group, and 5 in the placebo group.

List a potential confounding variable for this study and briefly explain a possible consequence it could have on the results.

Answer 1

The age of patients that include resistance power and the severity or stage of painful knee osteoarthritis are potential confounding variables for this study.

60 patients are randomly and evenly assigned into given 3 treatment groups (20 into each treatment) and obtained the results that may not be accurate and valid due to the effects of confounding variables of age and severity/stage of painful knee.

For example, in placebo group, 15 patients (20-5) who had no improvement are all of old age with less resistance power and/or they are in the final stage of painful knee (higher severity) and 16 in the chondroitin group who had improvement may be relatively younger people with more resistance power and/or they are in the beginning stage of painful knee(less severity). In this case, the results obtained have no validity at all. That is the effect of confounding and thus, it is necessary to consider all kinds of variables that have potential influence on the study and are to be controlled in order to get reliable results.