The role of sex-specific results reporting in cardiovascular disease. Cardiol Rev. 2007;15:275-278. [PMID: 18090061 DOI: 10.1097/crd.0b013e318158b45b]

Variability in Sleep Duration and Biomarkers of Cardiovascular Disease Across the Menstrual Cycle

Variability in sleep duration and cardiovascular health have been infrequently investigated, particularly among reproductive-age women. We examined these associations across the menstrual cycle among a cohort of 250 healthy premenopausal women, aged 18-44 years. The BioCycle study (New York, 2005-2007) collected cardiovascular biomarkers (serum high- and low-density lipoprotein (HDL, LDL), total cholesterol, triglycerides, and C-reactive protein (CRP)) at key time points along the menstrual cycle (follicular, ovulatory, and luteal phases). Women also recorded sleep duration in daily diaries. From these data, we computed L-moments, robust versions of location, dispersion, skewness, and kurtosis. We fitted linear mixed models with random intercepts and inverse probability weighting to estimate associations between sleep variability and cardiovascular biomarkers, accounting for demographic, lifestyle, health, and reproductive factors. Sleep dispersion (any deviation from mean duration) was associated with lower mean LDL for nonshift workers and non-White women. Skewed sleep duration was associated with higher mean CRP and lower mean total cholesterol. Sleep durations with extreme short and long bouts (kurtosis) were associated with a lower mean HDL, but not mean CRP, LDL, or triglycerides. Sleep duration modified associations between sleep dispersion and LDL, HDL, and total cholesterol. Even in young and healthy women, sleep duration variability could influence cardiovascular health.

Addressing persistent evidence gaps in cardiovascular sex differences research - the potential of clinical care data

Women have historically been underrepresented in cardiovascular clinical trials, resulting in a lack of sex-specific data. This is especially problematic in two situations, namely those where diseases manifest differently in women and men and those where biological differences between the sexes might affect the efficacy and/or safety of medication. There is therefore a pressing need for datasets with proper representation of women to address questions related to these situations. Clinical care data could fit this bill nicely because of their unique broad scope across both patient groups and clinical measures. This perspective piece presents the potential of clinical care data in sex differences research and discusses current challenges clinical care data-based research faces. It also suggests strategies to reduce the effect of these limitations, and explores whether clinical care data alone will be sufficient to close evidence gaps or whether a more comprehensive approach is needed.

Y Chromosome, Hypertension and Cardiovascular Disease: Is Inflammation the Answer?

It is now becomingly increasingly evident that the functions of the mammalian Y chromosome are not circumscribed to the induction of male sex. While animal studies have shown variations in the Y are strongly accountable for blood pressure (BP), this is yet to be confirmed in humans. We have recently shown modulation of adaptive immunity to be a significant mechanism underpinning Y-chromosome-dependent differences in BP in consomic strains. This is paralleled by studies in man showing Y chromosome haplogroup is a significant predictor for coronary artery disease through influencing pathways of immunity. Furthermore, recent studies in mice and humans have shown that Y chromosome lineage determines susceptibility to autoimmune disease. Here we review the evidence in animals and humans that Y chromosome lineage influences hypertension and cardiovascular disease risk, with a novel focus on pathways of immunity as a significant pathway involved.

Gender, blood pressure, and cardiovascular and renal outcomes in adults with hypertension from the Systolic Blood Pressure Intervention Trial

BACKGROUND

To determine if the effects of intensive lowering of systolic blood pressure (goal of less than 120 mmHg) versus standard lowering (goal of less than 140 mmHg) upon cardiovascular, renal, and safety outcomes differed by gender.

METHODS

Nine thousand three hundred and sixty-one men and women aged 50 years or older with systolic blood pressure of 130 mmHg or greater, taking 0-4 antihypertensive medications, and with increased risk of cardiovascular disease, but free of diabetes, were randomly assigned to either a systolic blood pressure target of less than 120 mmHg (intensive treatment) or a target of less than 140 mmHg (standard treatment). The primary composite outcome encompassed incident myocardial infarction, heart failure, other acute coronary syndromes, stroke, or cardiovascular-related death. All-cause mortality, renal outcomes, and serious adverse events were also assessed.

RESULTS

Compared with the standard treatment group, the primary composite outcome in the intensive treatment group was reduced by 16% [hazard ratio 0.84 (0.61-1.13)] in women, and by 27% in men [hazard ratio 0.73 (0.59-0.89), P value for interaction between treatment and gender is 0.45]. Similarly, the effect of the intensive treatment on individual components of the primary composite outcome, renal outcomes, and overall serious adverse events was not significantly different according to gender.

CONCLUSION

In adults with hypertension but not with diabetes, treatment to a systolic blood pressure goal of less than 120 mmHg, compared with a goal of less than 140 mmHg, resulted in no heterogeneity of effect between men and women on cardiovascular or renal outcomes, or on rates of serious adverse events.ClinicalTrials.gov number, NCT01206062.

Challenges in Sex- and Gender-Centered Prevention and Management of Cardiovascular Disease: Implications of Genetic, Metabolic, and Environmental Paths

The recognition of cardiovascular disease (CVD) as a "male" privilege has been a commonly held concept. However, emerging data describe another reality. Heterogeneities have been convincingly demonstrated regarding CVD manifestations, risk factor burden, and prognosis between males and females. The aim of the present narrative review was to highlight sex- and gender-related discrepancies in primary and secondary CVD prevention, underscoring plausible underlying mechanisms. Manifestation of CVD in women is characterized by atypical symptoms/signs and inadequately studied pathophysiology features challenging accurate diagnosis and effective treatment. Regarding CVD risk assessment, the burden and effect size of conventional, novel, and female-specific risk factors needs better clarification. Hitherto outcomes are nonconsistent, while most importantly, the interpretation of the attendant metabolic paths remains a challenge; the interactions among genetic, metabolic, and environmental factors are of high complexity regulated by genomic and nongenomic sex hormones effects. To deal with these key points, the National Institutes of Health currently calls upon investigators to provide a sex- and gender-specific reporting in all health research hypotheses. The implementation of high-quality studies addressing these issues is an imperative need to maximize cost-effectiveness in prevention and management strategies.

Cardiometabolic Risk in Hyperlipidemic Men and Women

Objective. The aim of this study was to evaluate sex specific differences of metabolic and clinical characteristics of treated hyperlipidemic men and women (HL-men and HL-women). Methods. In this study vascular and metabolic characteristics of 35 HL-women and 64 HL-men were assessed. In addition a sex specific analysis of metabolic and nutritional habits of HL-patients with prediabetes (HL-IGR) was done. Results. HL-women were older and had favourable concentrations of high density lipoprotein cholesterol (HDL-cholesterol), triglycerides (TG), and triglyceride/HDL-cholesterol ratio (TG/HDL-ratio) but were also shown to have higher concentrations of lipoprotein-a compared to HL-men. HL-men were characterized as having higher levels of liver-specific parameters and body weight as well as being more physically active compared to HL-women. Brain natriuretic peptide (pro-BNP) was higher in HL-women than HL-men, while no differences in metabolic syndrome and glycemic parameters were shown. HL-IGR-women were also older and still had a better profile of sex specific lipid parameters, as well as a lower body weight compared to HL-IGR-men. No differences were seen in vascular parameters such as the intima media thickness (IMT). Conclusion. HL-women were older and had overall more favourable concentrations of lipid parameters and liver enzymes but did not differ regarding vascular morphology and insulin sensitivity compared to HL-men of comparable body mass index (BMI).

Statin Adverse Events in Primary Prevention: Between Randomized Trials and Observational Studies

Considerable debate exists regarding who might benefit from statins for primary prevention. Statins have wide pleotropic effects, which contribute to their efficacy in lowering cardiovascular disease but may also result in adverse events (AEs). Caveats in identifying AEs in randomized controlled trials (RCTs) include the lack of a standardized definition of statin-associated AEs, the differences in properties of different statins, the selectivity of RCTs in choosing their participants, the presence of high rate of nonadherence/withdrawal from trials and other concerns related to study design and conflict of interest. Caveats in identifying or overestimating AEs in observational studies include failure to identify baseline confounders, ascertainment bias, confounding by indication and healthy user bias. Statin use in observational studies may be a surrogate marker for higher socioeconomic standards, access to health care or use of other preventive services. Integrating evidence from both RCTs and observational studies is of paramount importance for appropriate patient-centered decision.

Exercise vasodilation is greater in women: contributions of nitric oxide synthase and cyclooxygenase

PURPOSE

We hypothesized exercise vasodilation would be greater in women due to nitric oxide synthase (NOS) and cyclooxygenase (COX) signaling.

METHODS

45 healthy adults (23 women, W, 22 men, M, 26 ± 1 years) completed two 10-min trials of dynamic forearm exercise at 15 % intensity. Forearm blood flow (FBF; Doppler ultrasound), arterial pressure (brachial catheter), and forearm lean mass were measured to calculate relative forearm vascular conductance (FVCrel) = FBF 100 mmHg(-1) 100 g(-1) lean mass. Local intra-arterial infusion of L-NMMA or ketorolac acutely inhibited NOS and COX, respectively. In Trial 1, the first 5 min served as control exercise (CON), followed by 5 min of L-NMMA or ketorolac over the last 5 min of exercise. In Trial 2, the remaining drug was infused during 5-10 min, to achieve combined NOS-COX inhibition (double blockade, DB).

RESULTS

Are mean ± SE. Women exhibited 29 % greater vasodilation in CON (ΔFVCrel, 19 ± 1 vs. 15 ± 1, p = 0.01). L-NMMA reduced ΔFVCrel (p < 0.001) (W: Δ -2.3 ± 1.3 vs. M: Δ -3.7 ± 0.8, p = 0.25); whereas, ketorolac modestly increased ΔFVCrel (p = 0.04) similarly between sexes (W: Δ 1.6 ± 1.1 vs. M: Δ 2.0 ± 1.6, p = 0.78). DB was also found to be similar between the sexes (p = 0.85).

CONCLUSION

These data clearly indicate women produce a greater exercise vasodilator response. Furthermore, contrary to experiments in animal models, these data are the first to demonstrate vascular control by NOS and COX is similar between sexes.

The effect of gender medicine education in GP training: a prospective cohort study

The purpose of this study is to compare the change in general practitioner (GP) trainees' gender awareness following a modular gender medicine programme or a mainstream gender medicine programme. In 2007, a prospective study was conducted in three cohorts of in total 207 GP trainees who entered GP training in the Netherlands. The outcome measure was the Nijmegen Gender Awareness in Medicine Scale and a 16-item gender knowledge questionnaire. Two gender medicine teaching methods were compared: a modular approach (n = 75) versus a mainstream approach (n = 72). Both strategies were compared with a control cohort (n = 60). Statistical analysis included analysis of variance and t-tests. The overall response rates for the modular, mainstream and control cohort were 78, 72 and 82 %, respectively. There was a significant difference in change in gender knowledge scores between the modular cohort compared with the mainstream and control cohort (p = 0.049). There were no statistical differences between the cohorts on gender sensitivity and gender role ideology. At entry and end, female GP trainees demonstrated significantly higher gender awareness than male GP trainees. A modular teaching method is not a more favourable educational method to teach gender medicine in GP training. Female GP trainees are more gender aware, but male GP trainees are not unaware of gender-related issues.

Gender differences related to the presence of atrial fibrillation in older hypertensive patients

AIM: To determine whether there are gender differences in the epidemiological profile of atrial fibrillation (AF) and to characterise the clinical, biochemical, and therapeutic factors associated with AF.

METHODS: Each investigator (primary care physicians or physicians based in hospital units for hypertension treatment) recruited the first 3 patients with an age of ≥ 65 years and a clinical diagnosis of hypertension (ambulatory blood pressure monitoring and an electrocardiogram, were performed) on the first working day of the week for 5 wk and identified those individuals with atrial fibrillation. A binary logistic regression was performed, including all of the variables that were significant in the univariate analysis, to establish the variables that were associated with the presence of arrhythmia.

RESULTS: A total of 1028 patients were included in the study, with a mean age of 72.8 ± 5.8 years. Of these patients, 47.3% were male, 9% were smokers, 27.6% were diabetics, 48.3% had dyslipidaemia, 10.9% had angina, and 6.5% had experienced a myocardial infarction. Regarding gender differences, the men exhibited a larger waist circumference, a lower body mass index, less obesity, and a more extensive history of diabetes, smoking, ischaemic heart disease, kidney failure, peripheral arterial disease and carotid disease than the women. There were no differences, however, in the prevalence of AF between the men and the women (11.5% vs 9.2%, respectively; P = no significant). Regarding treatment, the women received antiplatelet agents and diuretics less frequently, but there were no other differences in the use of antihypertensive and antithrombotic therapies. In the multivariate analysis, AF in the total study population was associated with age, alcohol consumption, the presence of heart disease, and decreased glomerular filtration. In the women, AF was associated with all of the factors included in the overall analysis, as well as the presence of left ventricle hypertrophy. In contrast, in the men, the only risk factors associated with AF were age, the presence of heart disease and alcohol consumption.

CONCLUSION: In patients with hypertension over 65 years of age, there are relevant gender differences in the factors associated with AF.

Evaluating sex and gender competencies in the medical curriculum: a case study

BACKGROUND

Sex and gender differences exist in the manifestation and prevalence of many conditions and diseases. Yet many clinician training programs neglect to integrate this information across their curricula.

OBJECTIVE

This study aimed to measure the sex and gender medical knowledge of medical students enrolled in a program without an explicit directive to integrate sex and gender differences across a block system of core subjects.

METHODS

A forced-choice instrument consisting of 35 multiple-choice and true or false questions was adapted from an evaluation tool used in the European Curriculum in Gender Medicine held at Charité Hospital, Berlin, in September 2010.

RESULTS

Fourth-year (response rate 93%) and second-year (response rate 70%) students enrolled in Mayo Medical School completed the instrument. More than 50% of students in both classes indicated that topics related to sex and gender were covered in gynecology, cardiology, and pediatrics, and <20% of students indicated inclusion of such topics in nephrology, neurology, and orthopedics. More than twice as many second-year students indicated that topics dealing with sex and gender were included in immunology course material compared with fourth-year students. A consensus of written comments indicated that concepts of sex and gender-based medicine need to be embedded into existing curriculum, with an emphasis on clinically relevant information.

CONCLUSIONS

Although this study represents only one medical school in the United States, information regarding sex and gender aspects of medicine is not consistently included in this curriculum without an explicit directive. These results can provide guidance for curriculum improvement to train future physicians.

Strategies and methods to study sex differences in cardiovascular structure and function: a guide for basic scientists

Background

Cardiovascular disease remains the primary cause of death worldwide. In the US, deaths due to cardiovascular disease for women exceed those of men. While cultural and psychosocial factors such as education, economic status, marital status and access to healthcare contribute to sex differences in adverse outcomes, physiological and molecular bases of differences between women and men that contribute to development of cardiovascular disease and response to therapy remain underexplored.

Methods

This article describes concepts, methods and procedures to assist in the design of animal and tissue/cell based studies of sex differences in cardiovascular structure, function and models of disease.

Results

To address knowledge gaps, study designs must incorporate appropriate experimental material including species/strain characteristics, sex and hormonal status. Determining whether a sex difference exists in a trait must take into account the reproductive status and history of the animal including those used for tissue (cell) harvest, such as the presence of gonadal steroids at the time of testing, during development or number of pregnancies. When selecting the type of experimental animal, additional consideration should be given to diet requirements (soy or plant based influencing consumption of phytoestrogen), lifespan, frequency of estrous cycle in females, and ability to investigate developmental or environmental components of disease modulation. Stress imposed by disruption of sleep/wake cycles, patterns of social interaction (or degree of social isolation), or handling may influence adrenal hormones that interact with pathways activated by the sex steroid hormones. Care must be given to selection of hormonal treatment and route of administration.

Conclusions

Accounting for sex in the design and interpretation of studies including pharmacological effects of drugs is essential to increase the foundation of basic knowledge upon which to build translational approaches to prevent, diagnose and treat cardiovascular diseases in humans.

Response by sex to statin plus ezetimibe or statin monotherapy: a pooled analysis of 22,231 hyperlipidemic patients

Background

Despite documented benefits of lipid-lowering treatment in women, a considerable number are undertreated, and fewer achieve treatment targets vs. men.

Methods

Data were combined from 27 double-blind, active or placebo-controlled studies that randomized adult hypercholesterolemic patients to statin or statin+ezetimibe. Consistency of treatment effect among men (n = 11,295) and women (n = 10,499) was assessed and percent of men and women was calculated to evaluate the between-treatment ability to achieve specified treatment levels between sexes.

Results

Baseline lipids and hs-CRP were generally higher in women vs. men. Between-treatment differences were significant for both sexes (all p < 0.001 except apolipoprotein A-I in men = 0.0389). Men treated with ezetimibe+statin experienced significantly greater changes in LDL-C (p = 0.0066), non-HDL-C, total cholesterol, triglycerides, HDL-C, apolipoprotein A-I (all p < 0.0001) and apolipoprotein B (p = 0.0055) compared with women treated with ezetimibe+statin. The odds of achieving LDL-C < 100 mg/dL, apolipoprotein B < 90 mg/dL and the dual target [LDL-C < 100 mg/dL & apoliprotein B < 90 mg/dL] was significantly greater for women vs. men and the odds of achieving hs-CRP < 1 and < 2 mg/L and dual specified levels of [LDL-C < 100 mg/dL and hs-CRP < 2 mg/L] were significantly greater for men vs. women. Women reported significantly more gall-bladder-related, gastrointestinal-related, and allergic reaction or rash-related adverse events (AEs) vs. men (no differences between treatments). Men reported significantly more CK elevations (no differences between treatments) and hepatitis-related AEs vs. women (significantly more with ezetimibe+simvastatin vs. statin).

Conclusions

These results suggest that small sex-related differences may exist in response to lipid-lowering treatment and achievement of specified lipid and hs-CRP levels, which may have implications when managing hypercholesterolemia in women.

Inclusion of gender in emergency medicine research

BACKGROUND

Emergency physicians as front-line clinical specialists can directly advance patient care by understanding how gender-specific approaches may affect evaluation and management of diseases in the acute setting. Yet, it is unclear whether the role of gender is systematically examined in research focusing on emergency care.

OBJECTIVES

The objective was to determine if the effect of gender on health outcomes is examined in published studies targeting emergency medicine (EM).

METHODS

Using MEDLINE, the term "emergency" was used to identify all English-language, EM-related studies of adult human subjects published between January 2006 and April 2009 in which the first, second, or last author belonged to an EM section, division, center, or institution functioning as an emergency department (ED). The alternative chance-corrected statistic was used for intercoder reliability, and chi-square was used to calculate odds ratios (OR) with 95% confidence intervals (CIs). Articles were coded for gender composition, as well as use of gender as a control variable, independent variable, or part of the primary hypothesis.

RESULTS

The search revealed 2,487 articles using the selected "emergency" terms, and 750 original studies coded as EM-related publications were reviewed. The five topics contributing the most articles (44%) were administration/crowding, cardiovascular disease, emergency medical services, trauma, and sepsis. Seventy-nine percent of articles reported the gender composition of the sample, with 11% including gender as a control variable, 18% including gender as an independent variable, and 2% including gender in the primary hypothesis. The alternative chance-corrected statistic for evaluating gender composition was 0.90 (95% CI = 0.75 to 1.00). Use of gender in the analysis did not differ between federally funded studies versus non-federally funded studies (OR = 0.86; 95% CI = 0.5 to 1.4). The number of articles analyzing the effect of gender on a health outcome increased by 5% over the study period (27%-32%).

CONCLUSIONS

The majority of research articles targeted EM report gender as a demographic variable; however, few studies examined the effect of gender on health outcome. As the specialty advances into the next decade, the authors recommend that EM researchers 1) include both men and women in their study designs for appropriate gender comparisons; 2) report gender composition of study subjects and gender-specific comparisons study findings; and 3) report prognoses, outcomes, and interventions using gender as an independent variable in the study model.

Sex differences in the clinical and serologic presentation of early Lyme disease: Results from a retrospective review

BACKGROUND

Lyme disease is the most common vector-borne disease in the United States, and the number of reported cases has more than doubled between 1992 and 2008. Few studies have explicitly examined sex-based differences in the clinical presentation of or serologic response to early Lyme disease. It is unknown whether the sex-based variability observed in other infectious diseases is relevant to this clinical setting.

OBJECTIVE

This study retrospectively examined clinical and serologic differences by sex among a community case series of patients with a current or past episode of confirmed early Lyme disease.

METHODS

This was a retrospective, consecutive case series of adult patients in Maryland enrolled from August 2002 to August 2007 meeting criteria for a current or past episode of confirmed early Lyme disease. Clinical variables and patients' self-report surrounding illness onset were abstracted through chart review. All serologic tests drawn within 3 months of illness onset were interpreted using Centers for Disease Control and Prevention criteria.

RESULTS

In a total of 125 patients, there were no significant differences in clinical presentation by sex. The initial self-misdiagnosis rates for men and women were 10% and 18%, respectively (P = NS). Among the 62 patients with a serologic test as part of their clinical evaluation, 50% of men had a positive, 2-tier result compared with 32% of women (P = NS). Among the 41 patients with a positive ELISA, median ELISA values (3.4 vs 2.0; P = 0.03) and median number of immunoglobulin G (IgG) bands (4 vs 2; P = 0.03) were significantly higher among men.

CONCLUSIONS

In this small, retrospective sample, we found evidence for sex-based differences in the magnitude of ELISA and IgG serologic response to early Lyme disease. Such differences could have implications for appropriate diagnosis, treatment, and disease classification. Larger, prospective studies are needed to replicate the results found in this study and to examine their relationship to sex-based immunologic variability.

Sex/gender medicine. The biological basis for personalized care in cardiovascular medicine

Sex differences in morbidity and mortality associated with cardiovascular disease have been recognized by the medical community for decades. Investigation into the underlying biological basis of these differences was largely neglected by the scientific community until a report released by the Institute of Medicine in the United States in 2001 "Exploring the Biological Contributions to Human Health: Does Sex Matter?" Recommendations from this report included the need for more accurate use of the terms "sex" and "gender", better tools and resources to study the biological basis of sex differences, integration of findings from different levels of biological organization and continued synergy between basic and clinical researchers. Ten years after the Institute's report, this review evaluates some of the sex differences in cardiovascular disease, reviews new approaches to study sex differences and emphasizes areas where further research is required. In the era of personalized medicine, the study of the biological basis of sex differences promises to optimize preventive, diagnostic and therapeutic strategies for cardiovascular disease in men and women, but will require diligence by the scientific and medical communities to remember that sex does matter.

Sex differences in short-term heart rate variability in patients with newly diagnosed essential hypertension

The authors report the results of the analysis of heart rate variability (HRV) indices during 5 minutes of supine rest and 5 minutes of standing and conventional indices of autonomic function in 69 men and 51 women with untreated newly diagnosed hypertension matched for body mass index and resting blood pressure. Mean RR interval, standard deviation of normal-to-normal RR intervals, low-frequency RR spectral power, HRV during deep breathing at 6 breaths per minute, and the 30:15 ratio (maximum RR interval 30th beat/minimum RR interval 15th beat) were significantly lower in women (P=.01, .02, .001, .04, .01, respectively) compared with men. Low frequency RR in normalized units was lower in women in the supine position alone (P=.03). HRV was significantly lower in women with untreated newly diagnosed hypertension compared with men. The authors interpret these results as indicating an increase in baseline cardiac sympathovagal balance in female hypertensive patients.