Most biomedical studies fail to report if results differ by sex
Nearly three-quarters of biomedical studies fail to report whether outcomes differ for men and women, according to a study which raises concerns about gender bias.
Analysis of more than 11.5m medical research papers published between 1980 and 2016 found a majority overlooked the role of sex differences in genetics, physiology and the way the body responds to drugs.
“Female participants have often been underrepresented or excluded from research, with grave consequences,” said Vincent Larivière, of the University of Montréal, the paper’s senior author. “The inadequate consideration of sex differences … has led to disastrous results.”
For instance, the paper noted that of the 10 drugs withdrawn from the market between 1997 and 2001 eight posed greater health risks for women than for men.
In many studies and clinical trials, the exclusion of women was justified on the basis that their physiology is less stable because of the menstrual cycle. However, the paper said that “recent empirical research has shattered the myth of female variability” by showing that men show greater variability than women on several traits.
Inclusion of women in clinical trials has increased, the study said, but at the same time male bias has increased in animal and cell culture studies.
The study found female authors were more likely to report on sex-differences and journals with high-impact factors were less likely to report sex. Between 1980 and 2016, sex-related reporting increased across all types of health research included in the paper – from 59% to 67% in clinical medicine and from 36% to 69% in public health. However, progress in biomedical research was slower, increasing from 28% to 31%.
The study was published as part of a series of papers in the Lancet on the advancement of women in science and medicine. A commentary noted that medical textbooks are also heavily biased, with the male body remaining “the norm”. In 31 anatomy textbooks published between 1890 and 1989, about 70% of anatomical drawings were male, compared with fewer than 10% female (the remainder were classed as non-gendered). A more recent survey of 15 general medical and surgical textbooks found that 78% of depicted faces were male.