Sex differences at the platelet-vascular interface

Association of sex and aspirin use with postoperative bleeding in patients with lower extremity long bone fractures

Objective

The perioperative management of patients on antiplatelet drugs is a rising challenge in orthopedic trauma because antiplatelet drugs are frequently encountered and carry an increased risk of hemorrhagic consequences. The study objective was to examine the effect of aspirin on bleeding outcomes for patients with lower extremity fractures.

Methods

This retrospective study included patients requiring surgical fixation of traumatic hip, femur, and tibia fractures from January 1, 2018, to March 1, 2020. Patients were excluded if they had a significant head injury, were on chronic anticoagulant therapy, or they did not receive venous thromboembolism chemoprophylaxis. Comparisons between aspirin users (patients on aspirin therapy preinjury) and non-aspirin users were examined using χ2 tests, Cochran-Mantel-Haenszel tests, and multivariate logistic regression. The primary outcome was an overt, actionable bleed (eg, blood transfusion for surgical site hemorrhage) within 24 hours postoperative.

Results

There were 864 patients with lower extremity long bone fractures and 24% were aspirin users. The incidence of postoperative bleeding was 8.8% and significantly differed for patients taking aspirin versus not (13.6% vs 7.3%, p=0.01). However, biological sex at birth (M/F) was a significant effect modifier (interaction p=0.04). Among women, there were significantly more postoperative bleeds for aspirin users (17.8% aspirin vs 7.4% no aspirin, adjusted OR (AOR): 2.48 (1.28-4.81), p=0.01). Among men, there were similar postoperative bleeding events by aspirin use (5.6% aspirin vs 7.2% no aspirin, AOR: 0.50 (0.14-1.82), p=0.30). Postoperative hemoglobin values <8 g/dL were more frequent among female aspirin users (21.5% aspirin vs 12.5% no aspirin, p=0.01), but this association was not observed in men (p=0.43).

Conclusion

Women taking aspirin who suffer lower extremity fractures have greater than twofold greater odds of a postoperative bleeding event. These findings suggest adequate perioperative planning to ensure blood availability, and increased awareness to monitor closely for hemorrhage in the 24-hour postoperative window for women taking aspirin preinjury.

Level of evidence

IV.

Sex differences in functional outcomes of intravenous thrombolysis among patients with lacunar stroke

Background

This study aimed to assess if there are sex differences in the functional outcome of intravenous thrombolysis (IVT) among patients with lacunar stroke (LS).

Methods

Consecutive patients admitted from 1 January 2014 to 31 January 2020 to hospitals participating in the Swiss Stroke Registry presenting with LS and treated with IVT were included. The study population was then divided into two groups based on patient sex, and a multivariable ordinal logistic regression analysis was performed to uncover sex differences in the modified Rankin Scale (mRS) score at 90 days after stroke.

Results

A total of 413 patients with LS were treated with IVT: 177 (42.9%) women and 236 (57.1%) men. Women were older than men (median age 74 years, 25th-75th percentiles 67-84 years versus 70 years, 25th-75th percentiles 60-80 years, value of p 0.001) and, after adjustment for meaningful variables, showed more frequently increased odds of a higher mRS score at 90 days after stroke (adjusted odds ratio 1.49, 95% confidence interval 1.01-2.19, value of p 0.044).

Conclusion

This study showed that female sex increased the odds of a worse functional response to IVT in patients with LS. Future studies should further elucidate the mechanisms underlying such sex differences.

Stimulation of platelet P2Y1 receptors by different endogenous nucleotides leads to functional selectivity via biased signalling

BACKGROUND AND PURPOSE

Platelet function during inflammation is dependent on activation by endogenous nucleotides. Non-canonical signalling via the P2Y1 receptor is important for these non-thrombotic functions of platelets. However, apart from ADP, the role of other endogenous nucleotides acting as agonists at P2Y1 receptors is unknown. This study compared the effects of ADP, Ap3A, NAD+ , ADP-ribose, and Up4A on platelet functions contributing to inflammation or haemostasis.

EXPERIMENTAL APPROACH

Platelets obtained from healthy human volunteers were incubated with ADP, Ap3A, NAD+ , ADP-ribose, or Up4A, with aggregation and fibrinogen binding measured (examples of function during haemostasis) or before exposure to fMLP to measure platelet chemotaxis (an inflammatory function). In silico molecular docking of these nucleotides to the binding pocket of P2Y1 receptors was then assessed.

KEY RESULTS

Platelet aggregation and binding to fibrinogen induced by ADP was not mimicked by NAD+ , ADP-ribose, and Up4A. However, these endogenous nucleotides induced P2Y1 -dependent platelet chemotaxis, an effect that required RhoA and Rac-1 activity, but not canonical PLC activity. Analysis of molecular docking of the P2Y1 receptor revealed distinct differences of amino acid interactions and depth of fit within the binding pocket for Ap3A, NAD+ , ADP-ribose, or Up4A compared with ADP.

CONCLUSION AND IMPLICATIONS

Platelet function (aggregation vs motility) can be differentially modulated by biased-agonist activation of P2Y1 receptors. This may be due to the character of the ligand-binding pocket interaction. This has implications for future therapeutic strategies aimed to suppress platelet activation during inflammation without affecting haemostasis as is the requirement of current ant-platelet drugs.

LINKED ARTICLES

This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Interactions of platelets with obesity in relation to lung cancer risk in the UK Biobank cohort

BACKGROUND

Platelet count (PLT) is associated positively with lung cancer risk but has a more complex association with body mass index (BMI), positive only in women (mainly never smokers) and inverse in men (mainly ever smokers), raising the question whether platelets interact with obesity in relation to lung cancer risk. Prospective associations of platelet size (an index of platelet maturity and activity) with lung cancer risk are unclear.

METHODS

We examined the associations of PLT, mean platelet volume (MPV), and platelet distribution width (PDW) (each individually, per one standard deviation increase) with lung cancer risk in UK Biobank men and women using multivariable Cox proportional hazards models adjusted for BMI and covariates. We calculated Relative Excess Risk from Interaction (RERI) with obese (BMI ≥ 30 kg/m2), dichotomising platelet parameters at ≥ median (sex-specific), and multiplicative interactions with BMI (continuous scale). We examined heterogeneity according to smoking status (never, former, current smoker) and antiaggregant/anticoagulant use (no/yes).

RESULTS

During a mean follow-up of 10.4 years, 1620 lung cancers were ascertained in 192,355 men and 1495 lung cancers in 218,761 women. PLT was associated positively with lung cancer risk in men (hazard ratio HR = 1.14; 95% confidence interval (CI): 1.09-1.20) and women (HR = 1.09; 95%CI: 1.03-1.15) but interacted inversely with BMI only in men (RERI = - 0.53; 95%CI: - 0.80 to - 0.26 for high-PLT-obese; HR = 0.92; 95%CI = 0.88-0.96 for PLT*BMI). Only in men, MPV was associated inversely with lung cancer risk (HR = 0.95; 95%CI: 0.90-0.99) and interacted positively with BMI (RERI = 0.27; 95%CI = 0.09-0.45 for high-MPV-obese; HR = 1.08; 95%CI = 1.04-1.13 for MPV*BMI), while PDW was associated positively (HR = 1.05; 95%CI: 1.00-1.10), with no evidence for interactions. The associations with PLT were consistent by smoking status, but MPV was associated inversely only in current smokers and PDW positively only in never/former smokers. The interactions with BMI were retained for at least eight years of follow-up and were consistent by smoking status but were attenuated in antiaggregant/anticoagulant users.

CONCLUSIONS

In men, PLT was associated positively and MPV inversely with lung cancer risk and these associations appeared hindered by obesity. In women, only PLT was associated positively, with little evidence for interaction with obesity.

Sex Differences in the Evaluation and Treatment of Stroke

There are differences in the prevalence and strength of risk factors in women, along with sex-specific risk factors such as pregnancy. Women have a higher lifetime risk of stroke compared to men, with worse outcomes including higher rates of death and disability. We have made strides in the identification of sex-specific risk factors but with the paucity of sex-specific end points in clinical trials, stroke treatment and research are hindered.

Mean platelet volume as a predictive biomarker for in-hospital mortality in patients receiving invasive mechanical ventilation

Background

Although mean platelet volume (MPV) has been reported to be associated with poor prognosis of various critical illness, the relationship between MPV and in-hospital mortality among patients undergoing invasive mechanical ventilation (IMV) is unclear.

Methods

A retrospective observational study including patients receiving IMV was conducted from January, 2014 to January, 2019. The patients were divided into two groups by MPV cutoff value. The receiver operating characteristics curve was used to evaluate the predictive ability of MPV for in-hospital mortality. Univariate and multivariate Cox regression analysis were conducted to analyze the value of MPV for predicting in-hospital mortality. Kaplan–Meier cumulative incidence curve was employed to observe the incidence of in-hospital mortality.

Results

A total of 274 patients were enrolled in the study, and 42 patients (15.3%) died in hospital. MPV > 11.4 fl was a valuable predictor for in-hospital mortality (AUC0.848; 95%CI, 0.800–0.889) with sensitivity 66.7%, and specificity = 86.21%. MPV > 11.4 fl was an independent risk factor for in-hospital mortality (adjusted HR 2.640, 95%CI, 1.208–5.767, P = 0.015). Compared to the group of MPV ≤ 11.4 fl, patients with MPV > 11.4 fl had increased mortality (log-rank test = 40.35, HR = 8.723, P < 0.0001). The relationship between MPV and in-hospital mortality was stronger in female patients than in male patients.

Conclusion

MPV > 11.4 fl is a more useful marker for predicting in-hospital mortality among critically ill patients receiving IMV, especially in female patients. Attention to the MPV marker is simple and profitable with immediate applicability in daily clinical practice.