On the Basis of Sex

Trends of Sex Differences and Associated Factors in Stroke Outcomes Among Patients With Acute Ischemic Stroke: 2007 to 2018

BACKGROUND AND OBJECTIVES

Female patients have been shown to experience worse clinical outcomes after acute ischemic stroke (AIS) compared with male patients. We aimed to estimate the temporal trends in the sex differences in stroke outcomes and identify risk factors contributing to the sex differences spanning 10 years in China.

METHODS

This cohort study was conducted based on data from the China National Stroke Registries (CNSRs, comprising 3 phases, I-III, from 2007 to 2018). Patients with ischemic stroke within 7 days of symptom onset were included. The primary outcome was a 12-month poor functional outcome. Other outcomes included mortality and disability-adjusted life-year (DALY) lost. The sex differences in outcomes and associated factors were estimated using multivariable logistic regression. The sex differences between CNSRs were tested by the interaction of sex and time.

RESULTS

Among 42,564 patients included, 35.4% were female. The age-adjusted event rate of 12-month poor functional outcome and mortality decreased both in male and female patients after stroke onset (CNSRs I, II, and III, all p varies over time <0.001). There was a decrease in DALY lost for both sexes over the decade (male patients: from 10.1 to 9.3 DALYs; female patients: from 10.9 to 9.6 DALYs). Female patients showed worse 12-month poor functional outcome in CNSRs I and II (odds ratio [OR] with 95% CI: 1.24 [1.10-1.39] and 1.12 [1.01-1.25], respectively) compared with male patients, but the sex difference attenuated in CNSR III (OR with 95% CI: 1.02 [0.89-1.16]), with the temporal trend (p varies over time = 0.004). The sex difference and the temporal trend of the sex difference in mortality from 2007 to 2018 were not found (p varies over time = 0.45). The most important factors attenuating the sex difference in poor functional outcome in CNSRs I and III were education level, socioeconomic deprivation, baseline stroke severity, and current smoking.

DISCUSSION

This study demonstrated that the sex disparity in poor functional outcome at 12 months was substantially narrowed covering 10 years and completely attenuated in 2015-2018. The findings suggested that female patients have experienced larger improvements in stroke outcomes than male patients over the past decade.

Predicting motor gains with home-based telerehabilitation after stroke

INTRODUCTION

Telerehabilitation (TR) may be useful for rehabilitation therapy after stroke. However, stroke is a heterogeneous condition, and not all patients can be expected to derive the same benefit from TR, underscoring the need to identify predictors of response to TR.

METHODS

A prior trial provided patients with 6 weeks of intensive rehabilitation therapy targeting arm movement, randomly assigned to be provided in the home via TR (current focus) or in clinic. Eligible patients had moderate arm motor deficits and were in the subacute-chronic stage post stroke. Behavioral gains were measured as change in the arm motor Fugl-Meyer score from baseline to 30 days post therapy. To delineate predictors of TR response, multivariable linear regression was performed, advancing the most significant predictor from each of eight categories: patient demographics, stroke characteristics, medical history, rehabilitation therapy outside of study procedures, motivation, sensorimotor impairment, cognitive/affective deficits, and functional status.

RESULTS

The primary focus was on patients starting TR >90 days post stroke onset (n = 44), among whom female sex, less spasticity, and less visual field defects predicted greater motor gains. This model explained 39.3% of the variance in treatment-related gains. In secondary analysis that also included TR patients enrolled ≤90 days post stroke (total n = 59), only female sex was a predictor of treatment gains. A separate secondary analysis examined patients >90 days post stroke (n = 34) randomized to in-clinic therapy, among whom starting therapy earlier post stroke and less ataxia predicted greater motor gains.

DISCUSSION

Response to TR varies across patients, emphasizing the need to identify characteristics that predict treatment-related behavioral gain. The current study highlights factors that might be important to patient selection for home-based TR after stroke.

Impairments and Compensation in String-pulling After Middle Cerebral Artery Occlusion in the Rat

Stroke is a leading cause of long-term disability in humans, and it is frequently associated with impairments in the skilled use of the arms and hands. Many human upper limb impairments and compensatory changes have been successfully modeled in rodent studies of neocortical stroke, especially those that evaluate single limb use in tasks, such as reaching for food. Humans also use their hands for bilaterally coordinated movements, dependent upon interhemispheric cortical projections, which are also compromised by unilateral stroke. This study describes middle cerebral artery occlusion (MCAO) dependent changes in the bilaterally dependent hand use behavior of string-pulling in the rat. The task involves making hand-over-hand movements to pull down a string that contains a food reward attached to its end. MCAO rats missed the string more often with both hands than Sham rats. When the string was missed on the contralateral to MCAO body side, rats continued to cycle through subcomponents of string-pulling behavior as if the string were grasped in the hand. Rats also failed to make a grasping motion with the contralateral to MCAO hand when the string was missed and instead, demonstrated an open-handed raking-like motions. Nevertheless, with repeated attempts, rats performed components of string-pulling well enough to obtain a reward on the end of the string. Thus, string-pulling behavior is sensitive to bilateral impairments but is achieved with compensatory adjustments following MCAO. These aspects of MCAO string-pulling provide a foundation for studies that investigate the efficacy of therapeutic intervention which might enhance neuroplasticity and recovery. DATA AVAILABILITY: The datasets generated during the current study are available upon request.

Sex differences in imaging and clinical characteristics of patients from the WAKE-UP trial

BACKGROUND AND PURPOSE

Sex-based differences in acute ischemic stroke are a well-known phenomenon. We aimed to explore these differences between women and men in the Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke (WAKE-UP) trial.

METHODS

We compared baseline demographic and imaging characteristics (visual fluid-attenuated inversion recovery [FLAIR] positivity, relative FLAIR signal intensity, collateral status) between women and men in all screened patients. In randomized patients (i.e., those with diffusion-weighted imaging (DWI)-FLAIR mismatch), we evaluated a modifying role of sex on the treatment effect of alteplase in multivariable logistic regression, with treatment adjusted for National Institute of Health Stroke Scale (NIHSS) score and age. Dependent variables were modified Rankin Scale (mRS) score of 0-1 at 90 days and distribution of mRS scores at 90 days.

RESULTS

Of 1362 screened patients, 529 (38.8%) were women. Women were older than men, had higher baseline NIHSS scores and smoked less frequently. FLAIR positivity of the DWI lesion was equally present in women (174/529, 33.1%) and men (273/833, 33.3%; p = 1.00) and other imaging variables also did not differ between the sexes. In a total of 503 randomized patients, of whom 178 were women (35.4%), sex did not modify the treatment effect of alteplase on mRS score 0-1 or on the total distribution of mRS scores.

CONCLUSION

As in many other stroke trials, more men than women were included in the WAKE-UP trial, but the presence of a visual DWI-FLAIR mismatch and the relative FLAIR signal intensity did not differ between the sexes. The treatment effect of alteplase was not modified by sex.

Sex-Associated Differences in Neurovascular Dysfunction During Ischemic Stroke

Neurovascular units (NVUs) are basic functional units in the central nervous system and include neurons, astrocytes and vascular compartments. Ischemic stroke triggers not only neuronal damage, but also dissonance of intercellular crosstalk within the NVU. Stroke is sexually dimorphic, but the sex-associated differences involved in stroke-induced neurovascular dysfunction are studied in a limited extend. Preclinical studies have found that in rodent models of stroke, females have less neuronal loss, stronger repairing potential of astrocytes and more stable vascular conjunction; these properties are highly related to the cerebroprotective effects of female hormones. However, in humans, these research findings may be applicable only to premenopausal stroke patients. Women who have had a stroke usually have poorer outcomes compared to men, and because stoke is age-related, hormone replacement therapy for postmenopausal women may exacerbate stroke symptoms, which contradicts the findings of most preclinical studies. This stark contrast between clinical and laboratory findings suggests that understanding of neurovascular differences between the sexes is limited. Actually, apart from gonadal hormones, differences in neuroinflammation as well as genetics and epigenetics promote the sexual dimorphism of NVU functions. In this review, we summarize the confirmed sex-associated differences in NVUs during ischemic stroke and the possible contributing mechanisms. We also describe the gap between clinical and preclinical studies in terms of sexual dimorphism.

Female Stroke: Sex Differences in Acute Treatment and Early Outcomes of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Men and women are differently affected by acute ischemic stroke (AIS) in many aspects. Prior studies on sex disparities were limited by moderate sample sizes, varying years of data acquisition, and inconsistent inclusions of covariates leading to controversial findings. We aimed to analyze sex differences in AIS severity, treatments, and early outcome and to systematically evaluate the effect of important covariates in a large German stroke registry.

METHODS

Analyses were based on the Stroke Registry of Northwestern Germany from 2000 to 2018. We focused on admission-stroke severity and disability, acute recanalization treatment, and early stroke outcomes. Potential sex divergences were investigated via odds ratio (OR) using logistic regression models. Covariates were introduced in 3 steps: (1) base models (age and admission year), (2) partially adjusted models (additionally corrected for acute stroke severity and recanalization treatment), (3) fully adjusted models (additionally adjusted for onset-to-admission time interval, prestroke functional status, comorbidities, and stroke cause). Models were separately fitted for the periods 2000 to 2009 and 2010 to 2018.

RESULTS

Data from 761 106 patients with AIS were included. In fully adjusted models, there were no sex differences with respect to treatment with intravenous thrombolysis (2000-2009: OR, 0.99 [95% CI, 0.94-1.03]; 2010-2018: OR, 1.0 [0.98-1.02]), but women were more likely to receive intraarterial therapy (2010-2018: OR, 1.12 [1.08-1.15]). Despite higher disability on admission (2000-2009: OR, 1.10 [1.07-1.13]; 2010-2018: OR, 1.09 [1.07-1.10]), female patients were more likely to be discharged with a favorable functional outcome (2003-2009: OR, 1.05 [1.02-1.09]; 2010-2018: OR, 1.05 [1.04-1.07]) and experienced lower in-hospital mortality (2000-2009: OR, 0.92 [0.86-0.97]; 2010-2018: OR, 0.91 [0.88-0.93]).

CONCLUSIONS

Female patients with AIS have a higher chance of receiving intraarterial treatment that cannot be explained by clinical characteristics, such as age, premorbid disability, stroke severity, or cause. Women have a more favorable in-hospital recovery than men because their higher disability upon admission was followed by a lower in-hospital mortality and a higher likelihood of favorable functional outcome at discharge after adjustment for covariates.