How to study the impact of sex and gender in medical research: a review of resources

A deeper consideration of sex/gender in quantitative health research: a checklist for incorporating multidimensionality, variety, embodiment, and intersectionality throughout the whole research process

BACKGROUND

There is a growing awareness of the need to adequately integrate sex and gender into health-related research. Although it is widely known that the entangled dimensions sex/gender are not comprehensively considered in most studies to date, current publications of conceptual considerations and guidelines often only give recommendations for certain stages of the research process and - to the best of our knowledge - there is a lack of a detailed guidance that accompanies each step of the entire research process. The interdisciplinary project "Integrating gender into environmental health research" (INGER) aimed to fill this gap by developing a comprehensive checklist that encourages sex/gender transformative research at all stages of the research process of quantitative health research. In the long term this contributes to a more sex/gender-equitable research.

METHODS

The checklist builds on current guidelines on sex/gender in health-related research. Starting from important key documents, publications from disciplines involved in INGER were collected. Furthermore, we used a snowball method to include further relevant titles. The identification of relevant publications was continued until saturation was reached. 55 relevant publications published between 2000 and 2021 were identified, assessed, summarised and included in the developed checklist. After noticing that most publications did not cover every step of the research process and often considered sex/gender in a binary way, the recommendations were modified and enriched based on the authors' expertise to cover every research step and to add further categories to the binary sex/gender categories.

RESULTS

The checklist comprises 67 items in 15 sections for integrating sex/gender in quantitative health-related research and addresses aspects of the whole research process of planning, implementing and analysing quantitative health studies as well as aspects of appropriate language, communication of results to the scientific community and the public, and research team composition.

CONCLUSION

The developed comprehensive checklist goes beyond a binary consideration of sex/gender and thus enables sex/gender-transformative research. Although the project INGER focused on environmental health research, no aspects that were specific to this research area were identified in the checklist. The resulting comprehensive checklist can therefore be used in different quantitative health-related research fields.

Sex as a biological variable for cardiovascular physiology

There have been ongoing efforts by federal agencies and scientific communities since the early 1990s to incorporate sex and/or gender in all aspects of cardiovascular research. Scientific journals provide a critical function as change agents to influence transformation by encouraging submissions for topic areas, and by setting standards and expectations for articles submitted to the journal. As part of ongoing efforts to advance sex and gender in cardiovascular physiology research, the American Journal of Physiology-Heart and Circulatory Physiology recently launched a call for papers on Considering Sex as a Biological Variable. This call was an overwhelming success, resulting in 78 articles published in this collection. This review summarizes the major themes of the collection, including Sex as a Biological Variable Within: Endothelial Cell and Vascular Physiology, Cardiovascular Immunity and Inflammation, Metabolism and Mitochondrial Energy, Extracellular Matrix Turnover and Fibrosis, Neurohormonal Signaling, and Cardiovascular Clinical and Epidemiology Assessments. Several articles also focused on establishing rigor and reproducibility of key physiological measurements involved in cardiovascular health and disease, as well as recommendations and considerations for study design. Combined, these articles summarize our current understanding of sex and gender influences on cardiovascular physiology and pathophysiology and provide insight into future directions needed to further expand our knowledge.

The role of microRNAs in understanding sex-based differences in Alzheimer's disease

BACKGROUND

The incidence of Alzheimer's disease (AD)-the most frequent cause of dementia-is expected to increase as life expectancies rise across the globe. While sex-based differences in AD have previously been described, there remain uncertainties regarding any association between sex and disease-associated molecular mechanisms. Studying sex-specific expression profiles of regulatory factors such as microRNAs (miRNAs) could contribute to more accurate disease diagnosis and treatment.

METHODS

A systematic review identified six studies of microRNA expression in AD patients that incorporated information regarding the biological sex of samples in the Gene Expression Omnibus repository. A differential microRNA expression analysis was performed, considering disease status and patient sex. Subsequently, results were integrated within a meta-analysis methodology, with a functional enrichment of meta-analysis results establishing an association between altered miRNA expression and relevant Gene Ontology terms.

RESULTS

Meta-analyses of miRNA expression profiles in blood samples revealed the alteration of sixteen miRNAs in female and 22 miRNAs in male AD patients. We discovered nine miRNAs commonly overexpressed in both sexes, suggesting a shared miRNA dysregulation profile. Functional enrichment results based on miRNA profiles revealed sex-based differences in biological processes; most affected processes related to ubiquitination, regulation of different kinase activities, and apoptotic processes in males, but RNA splicing and translation in females. Meta-analyses of miRNA expression profiles in brain samples revealed the alteration of six miRNAs in female and four miRNAs in male AD patients. We observed a single underexpressed miRNA in female and male AD patients (hsa-miR-767-5p); however, the functional enrichment analysis for brain samples did not reveal any specifically affected biological process.

CONCLUSIONS

Sex-specific meta-analyses supported the detection of differentially expressed miRNAs in female and male AD patients, highlighting the relevance of sex-based information in biomedical data. Further studies on miRNA regulation in AD patients should meet the criteria for comparability and standardization of information.

Sexual Dimorphism in Substrate Metabolism During Exercise

During aerobic exercise, women oxidize significantly more lipids and less carbohydrates than men. This sexual dimorphism in substrate metabolism has been attributed, in part, to the observed differences in epinephrine and glucagon levels between men and women during exercise. To identify the underpinning candidate physiological mechanisms for these sex differences, we developed a sex-specific multi-scale mathematical model that relates cellular metabolism in the organs to whole-body responses during exercise. We conducted simulations to test the hypothesis that sex differences in the exercise-induced changes to epinephrine and glucagon would result in the sexual dimorphism of hepatic metabolic flux rates via the glucagon-to-insulin ratio (GIR). Indeed, model simulations indicate that the shift towards lipid metabolism in the female model is primarily driven by the liver. The female model liver exhibits resistance to GIR-mediated glycogenolysis, which helps maintain hepatic glycogen levels. This decreases arterial glucose levels and promotes the oxidation of free fatty acids. Furthermore, in the female model, skeletal muscle relies on plasma free fatty acids as the primary fuel source, rather than intramyocellular lipids, whereas the opposite holds true for the male model.

Guidelines on the use of sex and gender in cardiovascular research

In cardiovascular research, sex and gender have not typically been considered in research design and reporting until recently. This has resulted in clinical research findings from which not only all women, but also gender-diverse individuals have been excluded. The resulting dearth of data has led to a lack of sex- and gender-specific clinical guidelines and raises serious questions about evidence-based care. Basic research has also excluded considerations of sex. Including sex and/or gender as research variables not only has the potential to improve the health of society overall now, but it also provides a foundation of knowledge on which to build future advances. The goal of this guidelines article is to provide advice on best practices to include sex and gender considerations in study design, as well as data collection, analysis, and interpretation to optimally establish rigor and reproducibility needed to inform clinical decision-making and improve outcomes. In cardiovascular physiology, incorporating sex and gender is a necessary component when optimally designing and executing research plans. The guidelines serve as the first guidance on how to include sex and gender in cardiovascular research. We provide here a beginning path toward achieving this goal and improve the ability of the research community to interpret results through a sex and gender lens to enable comparison across studies and laboratories, resulting in better health for all.

Sex difference in liver diseases: How preclinical models help to dissect the sex-related mechanisms sustaining NAFLD and hepatocellular carcinoma

Only a few preclinical findings are confirmed in the clinic, posing a critical issue for clinical development. Therefore, identifying the best preclinical models can help to dissect molecular and mechanistic insights into liver disease pathogenesis while being clinically relevant. In this context, the sex relevance of most preclinical models has been only partially considered. This is particularly significant in NAFLD and HCC, which have a higher prevalence in men when compared to pre-menopause women but not to those in post-menopausal status, suggesting a role for sex hormones in the pathogenesis of the diseases. This review gathers the sex-relevant findings and the available preclinical models focusing on both in vitro and in vivo studies and discusses the potential implications and perspectives of introducing the sex effect in the selection of the best preclinical model. This is a critical aspect that would help to tailor personalized therapies based on sex.

"What's Sex and Gender Got to Do With It?" A Scoping Review of Sex- and Gender-Based Analysis in Pharmacoepidemiologic Studies of Medication Adherence

OBJECTIVES

Medication taking is a complex multidimensional behavior that may be impeded by a range of biological and psychosocial factors, including sex and gender. We aimed to synthesize how sex and gender have been reported and analyzed in pharmacoepidemiologic studies of medication.

METHODS

We searched for English-language peer-reviewed articles of observational studies (eg, cross-sectional, cohort, and case-control) that examined medication adherence among adults and included sex or gender in their reporting.

RESULTS

We included 937 studies among 530 537 287 participants published between the year 1979 and 2021. Most studies were cross-sectional (47%), lasted ≤ 1 year (35%), examined self-reported adherence (53%), did not assess specific adherence problem(s) (40%), and included medications for cardiovascular conditions (24%) or systemic infections (24%). A quarter of studies (25%) used sex and gender interchangeably, more than one third of studies (36%) that reported gender data likely collected data on sex, and < 1% of studies described sex and gender as distinct variables. Studies of cisgender participants more often reported that females/women experienced greater adherence problems often than males/men (31% vs 20%), particularly discontinuation and cost-related nonadherence. Only 21 studies (2%) reported on transgender individuals, and these predominantly examined antiretroviral medications for HIV.

CONCLUSIONS

Our review revealed substantial conflation of sex and gender in studies of medication adherence and a paucity of research among transgender individuals. Moreover, our synthesis showed sex/gender disparities in medication taking with studies reporting greater medication adherence problems among cisgender women and transgender participants than cisgender men.

Drug exposure during pregnancy in primary care: an algorithm and observational study from SIDIAP database, Catalunya, Spain

OBJECTIVES

To develop an algorithm to identify pregnancy episodes in women at childbearing age using SIDIAP (Information System for the Improvement of Research in Primary Care) data (Catalunya, Spain).To describe drugs dispensed during gestation.

DESIGN

Construction of an algorithm to identify all pregnancy episodes occurred from January 2011 to June 2020 in women aged 12-50. The variables used to create the algorithm include first day of last menstrual period, reasons for pregnancy termination and diagnoses registered in the primary healthcare records. Population-based cohort study including the pregnancy episodes identified by the algorithm.

SETTING

Catalonia, Spain.

PARTICIPANTS

All women aged 12-50 with at least one pregnancy episode occurred during January 2011-June 2020.

INTERVENTIONS

No interventions performed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Identification of pregnancy episodes through an algorithm and description of drug exposure.

RESULTS

We identified 327 865 pregnancy episodes in 250 910 people with a mean age of 31.3 years. During the study period, 83.4% of the episodes were exposed to at least one drug. The most frequent groups dispensed were iron preparations (48% of pregnancy episodes), iodine therapy (40.2%), analgesics and antipyretics (28%), penicillins (19.8%), vitamin B12 plus folic acid (19.7%) and non-steroidal anti-inflammatory drugs (NSAIDs, 15.1%). The supplements were more frequently dispensed at least twice, and the drugs for acute conditions were mainly dispensed only once during the pregnancy episode.

CONCLUSIONS

We developed an algorithm to automatically identify the pregnancy periods in SIDIAP.We described prescription drugs used during pregnancy. The most used ones were supplements, analgesics, NSAID or antibiotics.SIDIAP might be an efficient database to study drug safety during pregnancy and the consequences of drug use in the offspring.

TRIAL REGISTRATION NUMBER

EUPAS37675.

A genderful research world: rapid review, design, and pilot study of an interactive platform for curated sex and gender health research resources

BACKGROUND

Integration of sex and gender into health research is best practice for designing and conducting equitable, rigorous scientific research. Many evidence-based resources exist to support researchers in this endeavour, but such resources often remain underutilized as they are difficult to find, are not publicly accessible, or are specific to a particular research phase, context, or population. The development and evaluation of a repository of resources was deemed important to create an accessible platform for promoting sex- and gender-integration in health research.

METHODS

A rapid review was conducted of critical resources for conducting sex and gender health research. These were integrated into a prototype website design (the Genderful Research World; GRW) that provided an interactive digital landscape for researchers to access these resources. A pilot study evaluated the GRW website for applicability, desirability, and usability with an international sample of 31 health researchers from various disciplines and career stages. Quantitative data from the pilot study was summarized with descriptive statistics. Qualitative data was summarized narratively and used to identify concrete elements for improvement in a second design iteration.

RESULTS

Results of the pilot study revealed that the GRW was considered user friendly and desirable by health researchers and helped them access relevant information. Feedback suggested that providing these resources in a playful way may enhance the experience of the user, particularly given the high 'desirability' scores and that users emphasized the interactive layout as being key to their intention to integrate it into their teaching endeavors. Key feedback from the pilot study (e.g., addition of resources specific to research with transgender populations, revision of website layout) was integrated into the current version of the website: www.genderfulresearchworld.com .

CONCLUSIONS

The present research suggests a utility for a repository of resources for integrating sex and gender considerations into research, and that providing a logical, intuitive means of cataloguing and navigating such resources is critical for usability. The results of this study may inform the development of other novel researcher-directed resource curation efforts to address health equity issues and encourage and support health researchers to integrate a sex and gender perspective in their work.

The quality of gender and sex integration in scientific articles resulting from health research funded by the Brazilian Ministry of Health 2004-2016

Aim

Integrating sex and gender into health research is critical to contributing to an ethical and more responsible science to address significant knowledge gaps, resulting in higher-quality evidence for all.

Subject and methods

Using the Essential Metrics for Assessing Sex and Gender Integration in Health Research Proposals Involving Human Participants, we evaluate the quality of the integration of sex and gender in the 350 scientific articles produced by 144 health studies funded by the Department of Science and Technology of the Brazilian Ministry of Health between 2004 and 2016.

Results

The results show that clinical research articles are the type of studies that most frequently report on sex differences, while population and public health research articles most frequently report on gender differences. Analysis of the quality of sex and gender integration reveals low levels of qualification in the items of the literature review and research objectives (section 1) and participant recruitment and retention (section 2). However, the data collection tools, data analysis, and knowledge translation (section 3) items were rated as excellent and good.

Conclusion

Funding agencies and public institutions should recognize the importance of the integration of sex and gender at all stages of the research process, for instance, through awareness and training for researchers and reviewers, clear requirements, and the possibility to use metrics in the evaluations process.

Sex and gender differences in the use of oral anticoagulants for non-valvular atrial fibrillation: A population-based cohort study in primary health care in catalonia

Objectives: To describe the sex and gender differences in the treatment initiation and in the socio-demographic and clinical characteristics of all patients initiating an oral anticoagulant (OAC), and the sex and gender differences in prescribed doses and adherence and persistence to the treatment of those receiving direct oral anticoagulants (DOAC). Material and methods: Cohort study including patients with non-valvular atrial fibrillation (NVAF) who initiated OAC in 2011-2020. Data proceed from SIDIAP, Information System for Research in Primary Care, in Catalonia, Spain. Results: 123,250 people initiated OAC, 46.9% women and 53.1% men. Women were older and the clinical characteristics differed between genders. Women had higher risk of stroke than men at baseline, were more frequently underdosed with DOAC and discontinued the DOAC less frequently than men. Conclusion: We described the dose adequacy of patients receiving DOAC, finding a high frequency of underdosing, and significantly higher in women in comparison with men. Adherence was generally high, only with higher levels in women for rivaroxaban. Persistence during the first year of treatment was also high in general, being significantly more persistent women than men in the case of dabigatran and edoxaban. Dose inadequacy, lack of adherence and of persistence can result in less effective and safe treatments. It is necessary to conduct studies analysing sex and gender differences in health and disease.

Gastroesophageal reflux disease incidence among male patients with irritable bowel syndrome: A single-center cross-sectional study in southern Iran

Background and Aim

Gastrointestinal reflux disease (GERD) and irritable bowel syndrome (IBS) are among the most common gastrointestinal disorders in which the overlap of these diseases and their syndromes has been frequently reported. In this study, we aimed to evaluate GERD incidence among IBS patients and the related risk factors.

Methods

Male patients aged 18-60 years with an impression of IBS and referred to the gastrointestinal clinic from March 2019 to 2020 in Shiraz, Iran, were included in this study.

Results

Among the 163 enrolled patients with an average age of 31.53 ± 9.38 years, 64 (39.3%) were diagnosed with GERD. Based on statistical analysis, there was a significant association between GERD and the IBS patients' age (P = 0.006), smoking (P = 0.011), and alcohol consumption (P = 0.043). Also, GERD among IBS patients was significantly associated with the type of IBS (P < 0.001), with IBS-D having the lowest incidence (19.4%) and IBS-M the highest incidence of GERD (66.7%). Based on multivariate analysis, smoking had a reverse and significant correlation with lower incidence of GERD (OR = -1.364; P = 0.002).

Conclusion

Our results demonstrate that among male IBS patients, younger age, smoking, and alcohol consumption were among the risk factors for GERD. These findings may provide further insight into the best approach to treating these diseases.

Genetic differences between smokers and never-smokers with lung cancer

Smoking is a major risk factor for lung cancer, therefore lung cancer epidemiological trends reflect the past trends of cigarette smoking to a great extent. The geographic patterns in mortality closely follow those in incidence. Although lung cancer is strongly associated with cigarette smoking, only about 15% of smokers get lung cancer, and also some never-smokers develop this malignancy. Although less frequent, lung cancer in never smokers is the seventh leading cause of cancer deaths in both sexes worldwide. Lung cancer in smokers and never-smokers differs in many aspects: in histological types, environmental factors representing a risk, and in genes associated with this disease. In this review, we will focus on the genetic differences between lung cancer in smokers versus never-smokers: gene expression, germ-line polymorphisms, gene mutations, as well as ethnic and gender differences. Finally, treatment options for smokers and never-smokers will be briefly reviewed.

Sex-Related Differences of Matrix Metalloproteinases (MMPs): New Perspectives for These Biomarkers in Cardiovascular and Neurological Diseases

It is now established that sex differences occur in clinical manifestation, disease progression, and prognosis for both cardiovascular (CVDs) and central nervous system (CNS) disorders. As such, a great deal of effort is now being put into understanding these differences and turning them into “advantages”: (a) for the discovery of new sex-specific biomarkers and (b) through a review of old biomarkers from the perspective of the “newly” discovered sex/gender medicine. This is also true for matrix metalloproteinases (MMPs), enzymes involved in extracellular matrix (ECM) remodelling, which play a role in both CVDs and CNS disorders. However, most of the studies conducted up to now relegated sex to a mere confounding variable used for statistical model correction rather than a determining factor that can influence MMP levels and, in turn, disease prognosis. Consistently, this approach causes a loss of information that might help clinicians in identifying novel patterns and improve the applicability of MMPs in clinical practice by providing sex-specific threshold values. In this scenario, the current review aims to gather the available knowledge on sex-related differences in MMPs levels in CVDs and CNS conditions, hoping to shed light on their use as sex-specific biomarkers of disease prognosis or progression.

Sex and gender differences in depressive symptoms in older workers: the role of working conditions

BACKGROUND

Female older workers generally leave the work force earlier than men. Depressive symptoms are a risk factor of early work exit and are more common in women. To extend working lives, pathways leading to these sex inequalities need to be identified. The aim of this study was to investigate the association of sex and gender with depressive symptoms in older workers, and the role of working conditions in this association.

METHODS

We used data from the Longitudinal Aging Study Amsterdam (2012-2013/2015-2016, n = 313). Our outcome was depressive symptoms, measured by the Center for Epidemiologic Studies Depression Scale. We included biological sex, a gender index ranging from masculine to feminine (consisting of six items measuring gender roles: working hours, income, occupation segregation, education, informal caregiving, time spent on household chores), and working conditions (physical demands, psychosocial demands, cognitive demands, autonomy, task variation, social support) in our models. We examined the differential vulnerability hypothesis, i.e., sex/gender moderates the association between working conditions and depressive symptoms, and the differential exposure hypothesis, i.e., working conditions mediate the association between sex/gender and depressive symptoms.

RESULTS

Female sex and feminine gender were both associated with more depressive symptoms. The differential vulnerability hypothesis was not supported by our results. We did find that femininity was negatively associated with autonomy and task variation. In turn, these working conditions were associated with fewer depressive symptoms. Thus, autonomy and task variation partially mediated the association between gender and depressive symptoms, supporting the differential exposure hypothesis. Mediation effects for sex inequalities were not significant.

CONCLUSIONS

Older female workers and older feminine workers have more depressive symptoms than their male/masculine counterparts. Autonomy and task variation appeared to be important in - partially - explaining gender differences in depressive symptoms rather than sex differences. By improving these conditions, gender inequality in mental health among older workers can be reduced, so that both genders have similar chances to reach the retirement age in good mental health.

Examination of Sex-Specific Participant Inclusion in Exercise Physiology Endothelial Function Research: A Systematic Review

Background

To combat historical underrepresentation of female participants in research, guidelines have been established to motivate equal participation by both sexes. However, the pervasiveness of female exclusion has not been examined in vascular exercise physiology research. The purpose of this study was to systematically quantify the sex-specific prevalence of human participants and identify the rationales for sex-specific inclusion/exclusion in research examining the impact of exercise on vascular endothelial function.

Methods

A systematic search was conducted examining exercise/physical activity and vascular endothelial function, assessed via flow mediated dilation. Studies were categorized by sex: male-only, female-only, or mixed sex, including examination of the sample size of males and females. Analysis was performed examining sex-inclusion criteria in study design and reporting and rationale for inclusion/exclusion of participants on the basis of sex. Changes in proportion of female participants included in studies were examined over time in 5 year cohorts.

Results

A total of 514 studies were identified, spanning 26 years (1996–2021). Of the total participants, 64% were male and 36% were female, and a male bias was identified (32% male-only vs. 12% female-only studies). Proportions of female participants in studies remained relatively constant in the last 20 years. Male-only studies were less likely to report sex in the title compared to female-only studies (27 vs. 78%, p < 0.001), report sex in the abstract (72 vs. 98%, p < 0.001) and justify exclusion on the basis of sex (15 vs. 55%, p < 0.001). Further, male-only studies were more likely to be conducted in healthy populations compared to female-only studies (p = 0.002). Qualitative analysis of justifications identified four themes: sex-specific rationale or gap in the literature, exclusion of females based on the hormonal cycle or sex-differences, maintaining congruence with the male norm, and challenges with recruitment, retention and resources.

Conclusions

This systematic review provides the first analysis of sex-based inclusion/exclusion and rationale for sex-based decisions in human vascular exercise physiology research. These findings contribute to identifying the impact of research guidelines regarding inclusion of males and females and the perceived barriers to designing studies with equal sex participation, in an effort to increase female representation in vascular exercise physiology research.

Systematic Review Registration:

CRD42022300388.

Gender difference in the relationship between lipid accumulation product index and pulse pressure in nondiabetic Korean adults: The Korean National Health and Nutrition Examination Survey 2013-2014

The present study was conducted to assess the association between the lipid accumulation product index (LAP) and pulse pressure (PP) by gender in nondiabetic Korean adults. This study used the data of 8,240 nondiabetic adults (3,577 men and 4,663 women) aged ≥ 20 years from the Korean National Health and Nutrition Examination Survey 2013-2014. Key findings from the study were as follows: first, the mean values of age for the overall population, men, and women were 49.59 ± 15.73 years, 49.26 ± 16.04 years, and 49.85 ± 15.47 years, respectively. Second, in women (n = 4,663), after adjustment for related variables and with quartile 1 of LAP as a reference, the odds ratios (ORs) of high PP (PP > 60 mmHg) were significantly higher in quartile 3 [1.735 (95% confidence interval [CI], 1.064-2.831)] and quartile 4 of LAP [2.271 (95% CI, 1.325-3.893)]. Third, high PP in men (n = 3,577) was not associated with the quartiles of LAP. Forth, after adjustment for related variables, the PP level was positively associated with the quartiles of LAP in women (p < .001) but not in men (p = .400). PP was positively associated with LAP in nondiabetic Korean women but not in men.

Sex and Gender Appraisal Tool-Systematic Reviews-2 and Participation-To-Prevalence Ratio assessed to whom the evidence applies in sepsis reviews

OBJECTIVES

To revise a sex and gender appraisal tool for systematic reviews (SGAT-SR) and apply it to Cochrane sepsis reviews.

STUDY DESIGN AND SETTING

The revision process was informed by existing literature on sex, gender, intersectionality, and feedback from an expert advisory board. We revised the items to consider additional factors associated with health inequities and appraised sex and gender considerations using the SGAT-SR-2 and female Participation-to-Prevalence Ratio (PPR) in Cochrane sepsis reviews.

RESULTS

SGAT-SR-2 consists of 19 questions appraising the review's sections and use of the terms sex and gender. amongst 71 SRs assessed, 50.7% included at least one tool item, the most frequent being the number of participants by sex or gender at included study-level (24/71 reviews). Only four reviews provided disaggregated data for the full set of included trials, while two considered other equity-related factors. Reviews rarely appraised possible similarities and differences across sex and gender. In half of a subset of reviews, female participants were under-represented relative to their share of the sepsis population (PPR<0.8).

CONCLUSION

The SGAT-SR-2 tool and the PPR can support the design and appraisal of systematic reviews to assess sex and gender considerations, address to whom evidence applies, and determine future research needs.

Gender role endorsement in first-episode schizophrenia spectrum disorders

Sex (a biological distinction) and gender (a social construct) are inter-related, but semi-independent measures. The aim of our research was to compare gender role endorsement between first-episode schizophrenia spectrum disorder patients (n=77) and matched controls (n=64). The Bem Sex Role Inventory (BSRI) was used to assess masculinity and femininity scores as separate linear measures. This well-known research instrument also allowed us to examine gender as a categorical measure based on sex-specific cut-off scores calculated for controls as our normative reference sample using a median-split technique. First, we found that both masculinity and femininity scores differed between patients and controls. The distribution of gender as a categorical measure also differed between the two groups. Post-hoc testing with correction for multiple comparisons identified masculinity scores in particular as being lower in both male and female patients compared to controls of the corresponding sex. In conclusion, lower masculinity scores reported for chronic schizophrenia also affects first-episode patients with minimal prior treatment exposure irrespective of their biological sex. Future studies would do well to examine the associations of sex and gender with clinical and treatment outcomes from the perspective of the neurodevelopmental model of schizophrenia as a proposed "disorder of the self".

[How to Study the Sex and Gender Effect in Biomedical Research?]

Men and women are different, but this difference has not been well reflected in clinical trials and preclinical studies of biomedical science. Gender medicine, which systematically analyzes research results according to sex and gender, has been emphasized to overcome this problem. On the other hand, researchers still have difficulty in applying gender medicine to their research. To perform rigorous gender medicine, using correct terms, a thorough literature review during research planning, appropriate statistical analysis and reporting, and cautious interpretation of the results are necessary. Applying gender medicine will increase the reproducibility of studies, promote discoveries, expand the study relevance, and ultimately improve patient care in both men and women. Here, this study reviewed the practical issues on applying gender medicine to both preclinical and clinical studies in the field of biomedical science.

Sex-specific and gender-specific aspects in patient-reported outcomes

Patient-reported outcomes (PROs) are important tools in patient-centred medicine and allow for individual assessment of symptom burden and aspects of patients’ quality of life. While sex and gender differences have emerged in preclinical and clinical medicine, these differences are not adequately represented in the development and use of patient-reported outcome measures. However, even in personalised approaches, undesirable biases may occur when samples are unbalanced for certain characteristics, such as sex or gender. This review summarises the current status of the literature and trends in PROs with a focus on sex and gender aspects.

Female under-representation in sepsis studies: a bibliometric analysis of systematic reviews and guidelines

OBJECTIVES

The objective of the study was to assess female representation in primary studies underpinning recommendations from clinical guidelines and systematic reviews for sepsis treatment in adults.

STUDY DESIGN AND SETTING

We conducted a bibliometric study. We removed studies pertaining to sex-specific diseases and included quasirandomized, randomized clinical trials (RCTs), and observational studies. We analyzed the female participation-to-prevalence ratio (PPR).

RESULTS

We included 277 studies published between 1973 and 2017. For the 246 studies for which sex data were available, the share of female participation was 40%. Females overall were under-represented relative to their share of the sepsis population (PPR 0.78). Disaggregated results were reported by sex in 57 studies. In univariate analyses, non-intensive care unit setting and consideration of other social health determinants were significantly associated with greater female participation (P < 0.001 and P = 0.023, respectively). In regression models, studies published in 1996 or later were likely to report sex, while RCTs were unlikely to do so (P = 0.019 and P < 0.001, respectively).

CONCLUSION

Our study points to female underenrollment in sepsis studies. Primary studies underpinning recommendations for sepsis have poorly reported their findings by sex.

Non-alcoholic Fatty Liver Disease as a Canonical Example of Metabolic Inflammatory-Based Liver Disease Showing a Sex-Specific Prevalence: Relevance of Estrogen Signaling

There is extensive evidence supporting the interplay between metabolism and immune response, that have evolved in close relationship, sharing regulatory molecules and signaling systems, to support biological functions. Nowadays, the disruption of this interaction in the context of obesity and overnutrition underlies the increasing incidence of many inflammatory-based metabolic diseases, even in a sex-specific fashion. During evolution, the interplay between metabolism and reproduction has reached a degree of complexity particularly high in female mammals, likely to ensure reproduction only under favorable conditions. Several factors may account for differences in the incidence and progression of inflammatory-based metabolic diseases between females and males, thus contributing to age-related disease development and difference in life expectancy between the two sexes. Among these factors, estrogens, acting mainly through Estrogen Receptors (ERs), have been reported to regulate several metabolic pathways and inflammatory processes particularly in the liver, the metabolic organ showing the highest degree of sexual dimorphism. This review aims to investigate on the interaction between metabolism and inflammation in the liver, focusing on the relevance of estrogen signaling in counteracting the development and progression of non-alcoholic fatty liver disease (NAFLD), a canonical example of metabolic inflammatory-based liver disease showing a sex-specific prevalence. Understanding the role of estrogens/ERs in the regulation of hepatic metabolism and inflammation may provide the basis for the development of sex-specific therapeutic strategies for the management of such an inflammatory-based metabolic disease and its cardio-metabolic consequences.

Validity of Algorithms for Identification of Individuals Suffering from Chronic Noncancer Pain in Administrative Databases: A Systematic Review

BACKGROUND

Secondary analysis of health administrative databases is indispensable to enriching our understanding of health trajectories, health care utilization, and real-world risks and benefits of drugs among large populations.

OBJECTIVES

This systematic review aimed at assessing evidence about the validity of algorithms for the identification of individuals suffering from nonarthritic chronic noncancer pain (CNCP) in administrative databases.

METHODS

Studies reporting measures of diagnostic accuracy of such algorithms and published in English or French were searched in the Medline, Embase, CINAHL, AgeLine, PsycINFO, and Abstracts in Social Gerontology electronic databases without any dates of coverage restrictions up to March 1, 2018. Reference lists of included studies were also screened for additional publications.

RESULTS

Only six studies focused on commonly studied CNCP conditions and were included in the review. Some algorithms showed a ≥60% combination of sensitivity and specificity values (back pain disorders in general, fibromyalgia, low back pain, migraine, neck/back problems studied together). Only algorithms designed to identify fibromyalgia cases reached a ≥80% combination (without replication of findings in other studies/databases).

CONCLUSIONS

In summary, the present investigation informs us about the limited amount of literature available to guide and support the use of administrative databases as valid sources of data for research on CNCP. Considering the added value of such data sources, the important research gaps identified in this innovative review provide important directions for future research. The review protocol was registered with PROSPERO (CRD42018086402).

Sex-Based Differences in Tensiomyography as Assessed in the Lower Erector Spinae of Healthy Participants: An Observational Study

BACKGROUND

Although there is mounting evidence on sex-linked differences in paraspinal muscle function, it is unknown whether sex-based variations in mechanical and contractile characteristics of the lumbar erector spinae (LES) can be monitored noninvasively in healthy participants at rest using tensiomyography (TMG).

HYPOTHESIS

Sex-specific effects in muscle displacement (Dm) and velocity of muscle deformation (Vd) will be observed via TMG assessed in the LES.

STUDY DESIGN

Observational study.

LEVEL OF EVIDENCE

Level 3.

METHODS

LES response was measured in a relaxed state in 40 healthy adults (20 females). Possible differences between the conditions were investigated using mixed-model analyses of variance. Two-stage hierarchical linear regression analyses were performed to predict the outcome of TMG Dm and Vd based on participant sex.

RESULTS

There were significant main effects of sex with large effect sizes for both TMG parameters, resulting from lower mean values in women compared with men (Dm, P < 0.01; Vd, P < 0.01). In contrast, neither the main effect of side (left vs right LES) nor the interaction between the side and sex reached significance (all P > 0.3). Introducing the sex variable in stage 2 of the regression analyses significantly improved the prediction of the TMG parameters (all ∆R² ≥ 0.18; all P < 0.01; all f² ≥ 0.29).

CONCLUSION

Sex-based differences in muscle stiffness and contractile characteristics could be observed by TMG on LES muscles in healthy individuals at rest. The data suggest that these disparities are not exclusively attributable to anthropometric measures but may be linked to intrinsic sex-based differences in skeletal muscle characteristics.

CLINICAL RELEVANCE

We recommend implementing TMG in a clinical setting using the obtained results as a basis to factor for the patient's biological sex when assessing effects of therapeutic/exercise regimens aiming at the optimization of myofascial tissue regeneration and performance.

Sex and gender differences and biases in artificial intelligence for biomedicine and healthcare

Precision Medicine implies a deep understanding of inter-individual differences in health and disease that are due to genetic and environmental factors. To acquire such understanding there is a need for the implementation of different types of technologies based on artificial intelligence (AI) that enable the identification of biomedically relevant patterns, facilitating progress towards individually tailored preventative and therapeutic interventions. Despite the significant scientific advances achieved so far, most of the currently used biomedical AI technologies do not account for bias detection. Furthermore, the design of the majority of algorithms ignore the sex and gender dimension and its contribution to health and disease differences among individuals. Failure in accounting for these differences will generate sub-optimal results and produce mistakes as well as discriminatory outcomes. In this review we examine the current sex and gender gaps in a subset of biomedical technologies used in relation to Precision Medicine. In addition, we provide recommendations to optimize their utilization to improve the global health and disease landscape and decrease inequalities.

Conducting gender-based analysis of existing databases when self-reported gender data are unavailable: the GENDER Index in a working population

OBJECTIVES

Growing attention has been given to considering sex and gender in health research. However, this remains a challenge in the context of retrospective studies where self-reported gender measures are often unavailable. This study aimed to create and validate a composite gender index using data from the Canadian Community Health Survey (CCHS).

METHODS

According to scientific literature and expert opinion, the GENDER Index was built using several variables available in the CCHS and deemed to be gender-related (e.g., occupation, receiving child support, number of working hours). Among workers aged 18-50 years who had no missing data for our variables of interest (n = 29,470 participants), propensity scores were derived from a logistic regression model that included gender-related variables as covariates and where biological sex served as the dependent variable. Construct validity of propensity scores (GENDER Index scores) were then examined.

RESULTS

When looking at the distribution of the GENDER Index scores in males and females, they appeared related but partly independent. Differences in the proportion of females appeared between groups categorized according to the GENDER Index scores tertiles (p < 0.0001). Construct validity was also examined through associations between the GENDER Index scores and gender-related variables identified a priori such as choosing/avoiding certain foods because of weight concerns (p < 0.0001), caring for children as the most important thing contributing to stress (p = 0.0309), and ability to handle unexpected/difficult problems (p = 0.0375).

CONCLUSION

The GENDER Index could be useful to enhance the capacity of researchers using CCHS data to conduct gender-based analysis among populations of workers.

Sex-Related Differences in Impact on Safety of Pharmacogenetic Profile for Colon Cancer Patients Treated with FOLFOX-4 or XELOX Adjuvant Chemotherapy

Polymorphisms contribute to inter-individual differences and show a promising predictive role for chemotherapy-related toxicity in colon cancer (CC). TOSCA is a multicentre, randomized, non-inferiority, phase III study conducted in high-risk stage II/stage III CC patients treated with 6 vs 3 months of FOLFOX-4 or XELOX adjuvant chemotherapy. During this post-hoc analysis, 218 women and 294 men were genotyped for 17 polymorphisms: TYMS (rs34743033, rs2853542, rs11280056), MTHFR (rs1801133, rs1801131), ERCC1 (rs11615), XRCC1 (rs25487), XRCC3 (rs861539), XPD (rs1799793, rs13181), GSTP1 (rs1695), GSTT1/GSTM1 (deletion +/−), ABCC1 (rs2074087), and ABCC2 (rs3740066, rs1885301, rs4148386). The aim was to assess the interaction between these polymorphisms and sex, on safety in terms of time to grade ≥3 haematological (TTH), grade ≥3 gastrointestinal (TTG) and grade ≥2 neurological (TTN) toxicity. Interactions were detected on TTH for rs1801133 and rs1799793, on TTG for rs13181 and on TTN for rs11615. Rs1799793 GA genotype (p = 0.006) and A allele (p = 0.009) shortened TTH in men. In women, the rs11615 CC genotype worsened TTN (co-dominant model p = 0.008, recessive model p = 0.003) and rs13181 G allele improved the TTG (p = 0.039). Differences between the two sexes in genotype distribution of rs1885301 (p = 0.020) and rs4148386 (p = 0.005) were found. We highlight that polymorphisms could be sex-specific biomarkers. These results, however, need to be confirmed in additional series.

Sex still matters: has the prevalence of male-only studies of drug effects on rodent behaviour changed during the past decade?

During the past 10 years, for a number of biomedical disciplines, including behavioural pharmacology, there have been appeals to include both sexes in animal studies of processes that are not sex specific. In 2007, a survey of experimental studies of drug or other chemical effects on rodent behaviour, published in five prominent journals over 20 months (February 2005 to September 2006, inclusive), revealed that 85% of these conducted with rats and 78% of these conducted with mice involved males only. This was in spite of the evidence of sex differences in responsiveness to an increasing number of compounds. To see if the situation has improved, the survey was repeated with the same journals for a comparable period namely, February 2016 to September 2017 (inclusive). Even though there have been repeated appeals for biomedical research that is not sex specific to involve both sexes, it was apparent that little has changed since 2005-2006, as 82% of rat and 75% of mouse studies were again conducted with males only. However, there was an increase in studies with mice, which may be owing to a greater interest in genetic factors. The male-only situation could be rectified by appropriate funding agencies and journals that publish behavioural pharmacological research insisting that both sexes must be included in research that is not sex specific along with valid scientific justification for single-sex studies, as now typifies some other disciplines.

Evidence Map: Reporting of Results by Sex or Gender in Randomized, Controlled Trials with Women Veteran Participants (2008 to 2018)

BACKGROUND

Higher participation of women in randomized, controlled trials (RCTs) has not led to significantly improved reporting of sex-stratified results. A recent evidence map of research on women veterans revealed that many studies did not report results by sex or gender. This study's objectives were to compare characteristics of RCTs with women veteran participants that did or did not report results by sex or gender and to assess how sex and gender are addressed in research with women veterans.

METHODS

We extended the prior evidence map with a systematic search for RCTs with women veterans, published between 2008 and 2018. We compared the characteristics of RCTs that reported results by sex or gender with those of RCTs that did not, and reviewed methodology and reporting of sex/gender analyses.

RESULTS

In addition to 11 studies from the prior evidence map, we assessed 1,820 abstracts for relevance and ultimately included 45 unique RCTs. Five trials included only women and 40 included both men and women (median, 14.3% women). Ten studies reported results by sex or gender. These trials were larger (median study size of n = 343.5 vs. n = 125.5) and included a higher median proportion of women participants (16.8% vs. 11.2%) than studies without sex/gender results. Ten of 11 trials that tested pharmacologic or device interventions did not report results by sex or gender.

CONCLUSIONS

Reporting of results by sex or gender remains low in veteran research, but may improve with larger studies and increased recruitment of women veterans into trials. Trials of pharmacologic or device interventions may be targets for future reporting requirements. Standardization could improve attention to sex and gender in methodology and reporting.

Central ANG-(1-7) infusion improves blood pressure regulation in antenatal betamethasone-exposed sheep and reveals sex-dependent effects on oxidative stress

Fetal exposure to betamethasone (BMX) as a consequence of glucocorticoid administration to women threatening premature delivery may lead to long-term deleterious effects on the cardiovascular system and dysregulation of blood pressure in exposed adults. Indeed, adult offspring of BMX sheep exhibit increased mean arterial pressure (MAP) and attenuated baroreflex sensitivity (BRS) that are associated with lower medullary and cerebrospinal fluid (CSF) angiotensin-(1-7) [(ANG-(1-7)] content. Thus we determined the effects of ANG-(1-7) supplementation in the CSF on MAP, BRS, blood pressure (BPV) and heart rate variability (HRV) in conscious animals. The peptide or artificial CSF (aCSF) was infused continuously into the lateral ventricle (intracerebroventricular) of 4-mo-old male and female BMX sheep for 2 wk. Analysis of data from males and females combined revealed that intracerebroventricular ANG-(1-7) significantly lowered MAP and heart rate and improved BRS as compared with baseline; intracerebroventricular aCSF did not change these indexes. Similar patterns were observed for altered hemodynamics and autonomic function produced by intracerebroventricular ANG-(1-7) in both sexes. Oxidative stress and MAP kinase (MAPK) activation were lower in tissues from the dorsomedial medulla (DMM) of ANG-(1-7)-treated males but were unchanged in the treated females, when assessed at the end of the treatment period. We conclude that in the face of ANG-(1-7) deficiency in CSF and medullary tissue in BMX sheep intracerebroventricular supplementation of ANG-(1-7) lowers MAP and restores the impaired autonomic function to a similar degree in both males and females; however, the attenuation of MAPK and oxidative stress within the DMM was evident only in males. NEW & NOTEWORTHY We demonstrate that intracerebroventricular angiotensin-(1-7) [(ANG-(1-7)] treatment for 2 wk in antenatal betamethasone-exposed sheep provides beneficial effects on blood pressure and autonomic function. The physiological improvements are accompanied by an attenuation of oxidative stress in males but not females. The finding that ANG-(1-7) supplementation lowers blood pressure and restores the impaired autonomic function in a model of fetal programming previously shown to exhibit a deficiency in cerebrospinal fluid and brain tissue illustrates the potential for new therapeutic strategies for reducing cardiovascular dysfunction arising from prenatal events.

Gender Differences in Cardiac Remodeling Induced by a High-Fat Diet and Lifelong, Low-Dose Cadmium Exposure

Childhood obesity, which is prevalent in developed countries, is a metabolic risk factor for cardiovascular disease. Cadmium (Cd), a ubiquitous environmental toxic metal, also has deleterious effects on the cardiovascular system. However, the combined effects of a high-fat diet (HFD) and lifelong, low-dose Cd exposure on cardiac remodeling remain unclear. This study aims to determine the effects of combined HFD and Cd exposure on cardiac remodeling, as well as gender-specific differences in the response. C57BL/6J mice were exposed to Cd at a low dose (L-Cd, 0.5 ppm) or high dose (H-Cd, 5 ppm) via drinking water from conception to sacrifice. After being weaned, the offspring mice were fed with a HFD (42% kcal from fat) for an additional 10 weeks. H-Cd exposure significantly increased Cd accumulation in the hearts of both parents and their offspring; a HFD showed no added effects on cardiac Cd content. H-Cd exposure increased cardiac metallothionein protein levels only in female mice, regardless of dietary intake. Histological analysis revealed that H-Cd exposure combined with a HFD induced cardiac hypertrophy and fibrosis only in female mice. This was further supported by elevated expression of ANP and COL1A1 protein levels along with COL1A1, COL1A2, and COL3A1 mRNA levels. Profibrotic markers PAI-1, CTGF, and FN were also elevated in HFD/H-Cd-exposed female mice. Levels of the oxidative stress marker 3-NT significantly increased in the hearts of HFD-fed female mice, whereas Cd exposure showed no additional effects. Of all the antioxidant markers examined, levels of CAT significantly increased in mice fed a HFD, regardless of gender and Cd exposure. In summary, a HFD combined with lifelong, low-dose Cd exposure induces cardiac hypertrophy and fibrosis in female but not male mice, a response that is independent of oxidative stress.

Sex-dependent expression of brain medullary MAP and PI3 kinases in adult sheep with antenatal betamethasone exposure

Antenatal betamethasone (BM) therapy for women in jeopardy of premature delivery accelerates the lung development in preterm infants and reduces infant mortality rates, but may induce early programming events with chronic cardiovascular consequences. In a sheep model of fetal programming, in utero BM-exposed (BMX) offspring as adults exhibit elevated mean arterial pressure (MAP), decreased baroreflex sensitivity (BRS) for the control of heart rate and insulin resistance accompanied by dysregulation of the brain renin-angiotensin (Ang) system (RAS). However, the status of signaling mechanisms in the brain dorsomedial medulla (DMM) of the BMX sheep that comprise both the mitogen activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) cellular pathways is unknown. Given the importance of these signaling pathways in the actions of Ang peptides as well as baroreflex function and autonomic integration, we applied both a kinase signaling array and associated individual immunoblots of the dorsomedial brain medulla from adult female and male sheep with antenatal BMX. MAPK and PI3K pathways were altered significantly in the BMX sheep in a sex-dependent manner. A protein array for kinases (PathScan® Intracellular Signaling Array Kit, Cell Signaling) and subsequent verification by immunoblot revealed that within the DMM, female BMX sheep exhibit lower expression of proteins in the PI3K pathway, while male BMX sheep show greater expression of p-MAPK pathway proteins extracellular signal regulated kinase (ERK) 1/2. We conclude that maladaptive changes in these two kinase pathways in the DMM may contribute to the chronic dysregulation of blood pressure in this model of fetal programming.

LiverSex Computational Model: Sexual Aspects in Hepatic Metabolism and Abnormalities

The liver is to date the best example of a sexually dimorphic non-reproductive organ. Over 1,000 genes are differentially expressed between sexes indicating that female and male livers are two metabolically distinct organs. The spectrum of liver diseases is broad and is usually prevalent in one or the other sex, with different contributing genetic and environmental factors. It is thus difficult to predict individual's disease outcomes and treatment options. Systems approaches including mathematical modeling can aid importantly in understanding the multifactorial liver disease etiology leading toward tailored diagnostics, prognostics and therapy. The currently established computational models of hepatic metabolism that have proven to be essential for understanding of non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC) are limited to the description of gender-independent response or reflect solely the response of the males. Herein we present LiverSex, the first sex-based multi-tissue and multi-level liver metabolic computational model. The model was constructed based on in silico liver model SteatoNet and the object-oriented modeling. The crucial factor in adaptation of liver metabolism to the sex is the inclusion of estrogen and androgen receptor responses to respective hormones and the link to sex-differences in growth hormone release. The model was extensively validated on literature data and experimental data obtained from wild type C57BL/6 mice fed with regular chow and western diet. These experimental results show extensive sex-dependent changes and could not be reproduced in silico with the uniform model SteatoNet. LiverSex represents the first large-scale liver metabolic model, which allows a detailed insight into the sex-dependent complex liver pathologies, and how the genetic and environmental factors interact with the sex in disease appearance and progression. We used the model to identify the most important sex-dependent metabolic pathways, which are involved in accumulation of triglycerides representing initial steps of NAFLD. We identified PGC1A, PPARα, FXR, and LXR as regulatory factors that could become important in sex-dependent personalized treatment of NAFLD.

Differences in renal ammonia metabolism in male and female kidney

Renal ammonia metabolism has a major role in the maintenance of acid-base homeostasis. Sex differences are well recognized as an important biological variable in many aspects of renal function, including fluid and electrolyte metabolism. However, sex differences in renal ammonia metabolism have not been previously reported. Therefore, the purpose of the current study was to investigate sex differences in renal ammonia metabolism. We studied 4-mo-old wild-type C57BL/6 mice fed a normal diet. Despite similar levels of food intake, and, thus, protein intake, which is the primary determinant of endogenous acid production, female mice excreted greater amounts of ammonia, but not titratable acids, than did male mice. This difference in ammonia metabolism was associated with fundamental structural differences between the female and male kidney. In the female mouse kidney, proximal tubules account for a lower percentage of the renal cortical parenchyma compared with the male kidney, whereas collecting ducts account for a greater percentage of the renal parenchyma than in male kidneys. To further investigate the mechanism(s) behind the greater ammonia excretion in female mice, we examined differences in the expression of proteins involved in renal ammonia metabolism and transport. Greater basal ammonia excretion in females was associated with greater expression of PEPCK, glutamine synthetase, NKCC2, Rhbg, and Rhcg than was observed in male mice. We conclude that there are sex differences in basal ammonia metabolism that involve both renal structural differences and differences in expression of proteins involved in ammonia metabolism.

Sex in basic research: concepts in the cardiovascular field

Women and men, female and male animals and cells are biologically different, and acknowledgement of this fact is critical to advancing medicine. However, incorporating concepts of sex-specific analysis in basic research is largely neglected, introducing bias into translational findings, clinical concepts and drug development. Research funding agencies recently approached these issues but implementation of policy changes in the scientific community is still limited, probably due to deficits in concepts, knowledge and proper methodology. This expert review is based on the EUGenMed project (www.eugenmed.eu) developing a roadmap for implementing sex and gender in biomedical and health research. For sake of clarity and conciseness, examples are mainly taken from the cardiovascular field that may serve as a paradigm for others, since a significant amount of knowledge how sex and oestrogen determine the manifestation of many cardiovascular diseases (CVD) has been accumulated. As main concepts for implementation of sex in basic research, the study of primary cell and animals of both sexes, the study of the influence of genetic vs. hormonal factors and the analysis of sex chromosomes and sex specific statistics in genome wide association studies (GWAS) are discussed. The review also discusses methodological issues, and analyses strength, weaknesses, opportunities and threats in implementing sex-sensitive aspects into basic research.

Sex as a biological variable: Drug use and abuse

The study of sex as a biological variable is a necessary emphasis across a wide array of endpoints, including basic neuroscience, medicine, mental health, physiology and behavior. The present review summarizes work from clinical and preclinical populations on sex differences in drug use and abuse, ranging from initiation to escalation/dysregulation and from drug cessation/abstinence to relapse. These differences are analyzed in the context of the addiction cycle conceptualization of Koob and his colleagues and address patterns of drug use (binge/intoxication), motivation underlying its use (withdrawal/negative affect) and likelihood and causes of craving and relapse of drug taking (preoccupation/anticipation). Following this overview, an assessment of the basis for the reported sex differences is discussed in the context of the affective (rewarding and aversive) properties of drugs of abuse and how such properties and their balance vary with sex and contribute to drug intake. Finally, the interaction of sex with several experiential (drug history) and subject (age) factors and how these interactions affect reward and aversion are discussed to highlight the importance of understanding such interactions in predicting drug use and abuse. We note that sex as a biological variable remains one of critical evaluation and that such investigations of sex differences in drug use and abuse continue and be expanded to assess all facets of their mediation, including these affective properties, how their balance may be impacted by the multiple conditions under which drugs are taken and how this overall balance affects drug use and addiction vulnerability.

Article Commentary: Sex- and Gender-Based Medicine: The Need for Precise Terminology

As our knowledge of sex- and gender-based medicine (SGBM) continues to grow, attention to precision in the use of related terminology is critical. Unfortunately, the terms sex and gender are often used interchangeably and incorrectly, both within and outside of the typical binary construct. On behalf of the Sex and Gender Women's Health Collaborative (SGWHC), a national organization whose mission is the integration of SGBM into research, health professions education, and clinical practice, our objective was to develop recommendations for the accurate use of SGBM terminology in research and clinical practice across medical specialties and across health professions. In addition, we reviewed the origins and evolution of SGBM terminology and described terms used when referring to individuals outside the typical binary categorization of sex and gender. Standardization and precision in the use of sex and gender terminology will lead to a greater understanding and appropriate translation of sex and gender evidence to patient care along with an accurate assessment of the impact sex and gender have on patient outcomes. In addition, it is critical to acknowledge that SGBM terminology will continue to evolve and become more precise as our knowledge of sex and gender differences in health and disease progresses.

Sex Differences: A Resultant of an Evolutionary Pressure?

Spurred by current research policy, we are witnessing a significant growth in the number of studies that observe and describe sexual diversities in human physiology and sex prevalence in a large number of pathologies. Yet we are far from the comprehension of the mechanisms underpinning these differences, which are the result of a long evolutionary history. This Essay is meant to underline female reproductive function as a driver for the positive selection of the specific physiological features that explain male and female differential susceptibility to diseases and metabolic disturbances, in particular. A clear understanding of the causes underlying sexual dimorphisms in the physio-pathology is crucial for precision medicine.