Sex bias persists in surgical research: A 5-year follow-up study

How do we treat our male and female patients? - A primer on gender-based health care inequities

Health is a fundamental human right, yet disparities in healthcare, based on gender, persist for women. These inequities stem from a patriarchal society that has regarded men as the default standard, leading to women being treated merely as smaller men. Contributing to these disparities are the gender stereotypes that pervade our society. Women possess differences in anatomy, physiology, psychology and social experience than men. To achieve health equity, it is vital to understand and be open to consider and evaluate these aspects in each individual patient. This requires an understanding of our own biases and a commitment to valuing diversity in both patient and caregiver. Improving equity and diversity throughout all aspects of the medical system will be necessary to provide optimal patient care for all.

Comparative Outcomes of Groin Hernia Repair by Sex Among Medicare Beneficiaries

OBJECTIVE

To compare the rates of operative recurrence between male and female patients undergoing groin hernia repair.

BACKGROUND DATA

Groin hernia repair is common but understudied in females. Limited prior work demonstrates worse outcomes among females.

METHODS

Using Medicare claims, we performed a retrospective cohort study of adult patients who underwent elective groin hernia repair between January 1, 2010 and December 31, 2017. We used a Cox proportional hazards model to evaluate the risk of operative recurrence up to 5 years following the index operation. Secondary outcomes included 30-day complications following surgery.

RESULTS

Among 118,119 patients, females comprised the minority of patients (n=16,056, 13.6%). Compared with males, female patients were older (74.8 vs. 71.9 y, P <0.01), more often white (89.5% vs. 86.7%, P <0.01), and had a higher prevalence of nearly all measured comorbidities. In the multivariable Cox proportional hazards model, we found that female patients had a significantly lower risk of operative recurrence at 5-year follow-up compared with males (aHR 0.70, 95% CI 0.60-0.82). The estimated cumulative incidence of recurrence was lower among females at all time points: 1 year [0.68% (0.67-0.68) vs. 0.88% (0.88-0.89)], 3 years [1.91% (1.89-1.92) vs. 2.49% (2.47-2.5)], and 5 years [2.85% (2.82-2.88) vs. 3.7% (3.68-3.75)]. We found no significant difference in the 30-day risk of complications.

CONCLUSIONS

We found that female patients experienced a lower risk of operative hernia recurrence following elective groin hernia repair, which is contrary to what is often reported in the literature. However, the risk of operative recurrence was low overall, indicating excellent surgical outcomes among older adults for this common surgical condition.

Comparison of safety and healthcare utilization following sleeve gastrectomy or gastric bypass among medicare beneficiaries using sex as a biologic variable

BACKGROUND

Bariatric surgery is a common operation, but differences in outcomes between males and females are unknown.

OBJECTIVES

To compare the risk of mortality, complications, reintervention, and healthcare utilization after sleeve gastrectomy or gastric bypass using sex as a biologic variable.

SETTING

United States.

METHODS

Retrospective cohort study of adults undergoing sleeve gastrectomy or gastric bypass from January 1, 2012 to December 31, 2018 using Medicare claims data. We performed a heterogeneity of treatment effect analysis to determine the impact of sleeve gastrectomy versus gastric bypass comparing males to females. The primary outcome was safety (mortality, complications, and reinterventions) up to 5 years after surgery. The secondary outcome was healthcare utilization (hospitalization and emergency department use).

RESULTS

Among 95,405 patients the majority (n = 71,348; 74.8%) were female and most (n = 57,008; 59.8%) underwent sleeve gastrectomy. For all patients, compared to gastric bypass, sleeve gastrectomy was associated with a lower risk of complications and reintervention but a higher risk of revision. Compared to gastric bypass, sleeve gastrectomy was associated with a lower risk of mortality for females (adjusted hazard ratio .86, 95% CI .75-.96) but not males. We found no difference in procedure treatment effect by sex for mortality, hospitalization, emergency department use, or overall reintervention when comparing sleeve to gastric bypass.

CONCLUSIONS

Females and males have similar outcomes following bariatric surgery. Females have a lower risk of complications but a higher risk of reintervention. Decisions surrounding treatment for this common procedure should be tailored to include a discussion of sex-specific differences in treatment outcome.

Gender Bias in Clinical Trial Enrollment: Female Authorship Matters

BACKGROUND

Despite initiatives to promote equal enrollment of human subjects in clinical trials, females continue to be underrepresented. The goal of this work is to determine if female enrollment in human clinical trials published in 3 high-impact journals from 2015 to 2019 is correlated with gender of first and/or senior authors.

METHODS

Clinical trials published in the Journal of the American Medical Association (JAMA), The Lancet, and the New England Journal of Medicine (NEJM) from January 1, 2015, to December 31, 2019, were reviewed. Trials were excluded for ongoing enrollment, sex-specific disease research, or author name without gender assignment. One-sample χ2 pairwise comparisons and two-tailed proportion tests on the proportion of females between gender author pairings were done overall and for each subset analysis.

RESULTS

In total, 1,427 articles enrolled a total of 2,104,509 females and 2,616,981 males (44.6% vs. 55.4%, P ≤ 0.0001) in clinical trials. Overall, more females were enrolled if both first and senior authors were female (51.7% vs. 48.3%, P ≤ 0.0001). Proportion of females enrolled decreased with the following first and senior author pairings: female-male (48.9%), male-female (48.6%), and male-male (40.5%, P ≤ 0.0001 compared to female-female authorship). Greater female enrollment in clinical trials with female-female compared to male-male authorship persisted in subset analyses by funding source, phase, randomization for study participants, drug and/or device trial, and geographic location. Female enrollment was higher in 3 surgical specialties: neurosurgery (all authors: 52%, P ≤ 0.01), ophthalmology (all authors: 53.6%, P ≤ 0.0001), and surgery (all authors: 54.4%, P ≤ 0.0001). The majority of surgical specialties did not publish trials with female-female authorship but when stratifying by author gender pairing, surgical oncology had the highest female enrollment with female-female authorship (98.4%, P ≤ 0.0001).

CONCLUSIONS

Female authorship of clinical trial publications, specifically having both first and senior authors as female, was correlated with higher female enrollment in clinical trials when compared to male authorship and endured with multiple subset analyses.

Minimal influence of estrous cycle on studies of female mouse behaviors

Introduction

Sex bias has been an issue in many biomedical fields, especially in neuroscience. In rodent research, many scientists only focused on male animals due to the belief that female estrous cycle gives rise to unacceptable, high levels of variance in the experiments. However, even though female sexual behaviors are well known to be regulated by estrous cycle, which effects on other non-sexual behaviors were not always consistent in previous reports. Recent reviews analyzing published literature even suggested that there is no evidence for larger variation in female than male in several phenotypes.

Methods

To further investigate the impact of estrous cycle on the variability of female behaviors, we conducted multiple behavioral assays, including the open field test, forced swimming test, and resident-intruder assay to assess anxiety-, depression-like behaviors, as well as social interaction respectively. We compared females in the estrus and diestrus stages across four different mouse strains: C57BL/6, BALB/c, C3H, and DBA/2.

Results

Our results found no significant difference in most behavioral parameters between females in these two stages. On the other hand, the differences in behaviors among certain strains are relatively consistent in both stages, suggesting a very minimal effect of estrous cycle for detecting the behavioral difference. Last, we compared the behavioral variation between male and female and found very similar variations in most behaviors between the two sexes.

Discussion

While our study successfully identified behavioral differences among strains and between the sexes, we did not find solid evidence to support the notion that female behaviors are influenced by the estrous cycle. Additionally, we observed similar levels of behavioral variability between males and females. Female mice, therefore, have no reason to be excluded in future behavioral research.