A review of the historical use of sex as a biological variable in the American Journal of Physiology-Heart and Circulatory Physiology

Abstract

Despite National Institute of Health (NIH) mandates requiring sex as a biological variable (SABV), female underrepresentation persists in research, driving the American Journal of Physiology-Heart and Circulatory Physiology (Am J Physiol-Heart Circ) to publish SABV expectations in 2021. To determine progress within the Am J Physiol-Heart Circ, this mini-review evaluated SABV during the first 6 mo of each decade from 1980 to 2020, and 2019, to mitigate pandemic influence. Of the 1,205 articles published, 1,087 articles were included in this review (articles without original research subjects were excluded), of which 72.9% identified subjects. There were consistently fewer female human participants than males, except within 2019 (1980: females n = 3, males n = 5; 1990: females n = 70, males n = 199; 2000: females n = 305, males n = 355; 2010: females n = 186, males n = 472; 2019: females n = 1,695, males n = 1,550; 2020: females n = 1,157, males n = 1,222) and fewer female animals than males (1980: females n = 58, males n = 1,291; 1990: females n = 447, males n = 2,628; 2000: females n = 590, males n = 3,083; 2010: females n = 663, males n = 4,517; 2019: females n = 338, males n = 1,340; 2020: females n = 1,372, males n = 1,973). Only 16 (12.3%) articles including humans discussed SABV from 1980 to 2020. There are persistent SABV disparities within Am J Physiol-Heart Circ with some improvements in recent years. It is imperative that organizations such as the American Physiological Society and NIH foster an expectation of SABV as the norm, not the exception.

Keywords: SABV; female underreporting in science; sex and gender equity; sex and race disparities; sex differences in cardiovascular health.

Figure 1.

Review flow diagram for the first 6 mo of 1980, 1990, 2000, 2010, 2019, and 2020. Am J Physiol-Heart Circ, American Journal of Physiology-Heart and Circulatory Physiology.

Figure 2.

A: number and types of articles published in American Journal of Physiology-Heart and Circulatory Physiology (Am J Physiol-Heart Circ) from 1980 to 2020 by decade, including 2019 to determine whether articles published in 2020 were influenced by the pandemic. B: representation of males in articles compared with females (%males) in human studies in the Am J Physiol-Heart Circ by decade from 1980 to 2020, including 2019 to account for potential influence of the pandemic. Percent difference was calculated as follows: (number of males represented − number of females represented)/(number of males represented) × 100. C: representation of males in articles compared with females (%males) in animal studies in the Am J Physiol-Heart Circ by decade from 1980 to 2020, including 2019 to account for potential influence of the pandemic. Percent difference was calculated as follows: (number of males represented − number of females represented)/(number of males represented) × 100.