Most medical journal articles reporting weight-loss studies do not reveal key patient characteristics that can bias the results.
Researchers at the University of Kansas School of Medicine found over 90 percent of diet studies did not accurately describe their subjects. They examined 231 articles from 1966 to 2003 reporting studies of obese adult participants to see if the articles included 21 variables such as age, gender, general health, medical use and ethnicity. These elements are crucial for a study to be valid, according to a panel of clinical investigators, epidemiologists, statisticians and journal editors.
Articles did not indicate medication use 92 percent of the time, ethnicity 86 percent of the time and health status 34 percent of the time, the researchers said, adding that changes in sample sizes at the beginning and end of studies frequently went unreported by gender.
“Without knowledge of the number of subjects who were lost to follow-up, readers are unable to judge the effectiveness of a clinical treatment or ascertain whether or not a research finding has practical significance,” said lead researcher Cheryl Gibson.