Immune dysfunction following trauma-haemorrhage: influence of gender and age

Pulmonary contusion causes impairment of macrophage and lymphocyte immune functions and increases mortality associated with a subsequent septic challenge*

OBJECTIVE AND DESIGN

Pulmonary contusion is frequently followed by acute respiratory distress syndrome, pneumonia, and sepsis. However, immunologic alterations of circulating and resident immune cell populations contributing to the posttraumatic immunosuppression are poorly understood. We therefore characterized the influence of pulmonary contusion on peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages. To address the significance of the immunosuppression associated with lung contusion, we investigated how the consecutive addition of moderate or severe sepsis affected survival after blunt chest trauma.

SUBJECTS

Male C3H/HeN mice (n = 10 per group) were anesthetized and subjected to chest trauma or sham procedure.

MEASUREMENTS

The cytokine release of cultured peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages and plasma levels of tumor necrosis factor-alpha and interleukin-6 from those animals were quantified. Sepsis was induced via cecal ligation and puncture 24 hrs after lung contusion.

MAIN RESULTS

Two hours after blunt chest trauma, plasma tumor necrosis factor-alpha and interleukin-6 were markedly increased, as was peripheral blood mononuclear cell cytokine production, lung myeloperoxidase activity, and lung chemokine concentrations. At 24 hrs and, in part, already at 2 hrs, cytokine release from peritoneal macrophages, splenic macrophages, and splenocytes was significantly suppressed. Furthermore, pulmonary contusion when followed by moderate sepsis significantly diminished survival rate when compared with chest trauma or moderate sepsis alone.

CONCLUSIONS

These results indicate that pulmonary contusion causes severe immunodysfunction of splenocytes, macrophages, and monocytes in different local compartments and systemically. Moreover, this immunosuppression is associated with an increased susceptibility to infectious complications, which results in a decreased survival rate if blunt chest trauma is followed by a septic insult.

Concept of PIRO as a new conceptual framework to understand sepsis

OBJECTIVE

To define and introduce the PIRO model for categorizing sepsis in infants and children.

DESIGN

A summary of the literature published during the 5 yrs since this concept has been formulated, along with a consensus opinion of experts in the field of sepsis and septic shock.

RESULTS

The imprecision and intrinsic heterogeneity of the patient population defined as septic has prompted the introduction of a new sepsis classification system known as PIRO. PIRO stands for predisposition, infection, response, and organ dysfunction. It is hoped that by defining the septic process through a detailed analysis of each of its component parts, the development of sepsis will be better understood. This may contribute to improved therapeutic interventions for sepsis in the future.

CONCLUSIONS

The PIRO model is a conceptual framework for understanding sepsis that has many favorable attributes. The PIRO model should be directly tested in both the research laboratory and in clinical trial designs to determine the practical value and clinical relevance of this new classification scheme for sepsis.

Differences in the expression of LPS-receptors are not responsible for the sex-specific immune response after trauma and hemorrhagic shock

Several studies demonstrated a sex-specific cytokine secretion by macrophages following trauma-hemorrhage (T-H) and incubation with lipopolysaccharide A (LPS). Although LPS is known to act via the receptors CD14 and TLR4 on macrophages, it remains unknown whether differences in LPS receptor expression in males and females may be responsible for the gender-specific LPS induced cytokine response following (T-H). To study this, male and proestrus female mice (C3H/HeN) were subjected to trauma (laparotomy) followed by hemorrhage or sham operation. At 2 h thereafter, SMphi and PMphi were harvested and cultured for 2 h. The expression of CD14 and TLR4 was measured by flow cytometry on unstimulated SMphi and PMphi as well as after LPS stimulation. The results indicate that the expression of CD14 and TLR4 on SMphi and PMphi from female and male mice was similar in sham-operated animals and after (T-H). Incubation of macrophages with LPS did not alter CD14 and TLR4 expression in the study groups. Thus, the sex specific LPS induced cytokine secretion after (T-H) is not caused by differences in LPS receptor expression on Mphi of male and female mice.

Are alterations of lymphocyte subpopulations in polymicrobial sepsis and DHEA treatment mediated by the tumour necrosis factor (TNF)-alpha receptor (TNF-RI)? A study in TNF-RI (TNF-RI(-/-)) knock-out rodents

Sepsis is associated with depression of T cell-dependent immune reactivity with proinflammatory cytokines, such as tumour necrosis factor (TNF)-alpha, playing an important role. Recent investigations describe an association between these immunological alterations and disturbances of the endocrine system, related most frequently to sex steroid hormones. Dehydroepiandrosterone (DHEA), one of the most abundant adrenal sex steroid precursors, seems to have a protective immunological effect towards septic insults. In this study, both the role of TNF-receptor I (RI) and possible interactions in the protective role of DHEA were investigated in a murine model of polymicrobial sepsis. Polymicrobial sepsis was induced by caecal ligation and puncture (CLP) in a murine model. The effects of DHEA on survival, clinical parameters and cellular immunity (T lymphocytes and natural killer (NK) cells) were investigated. CLP was performed in genetically modified TNF-RI knock-out (TNF-RI(-/-)) and genetically unmodified (wild-type, WT) mice. DHEA application was associated with a decrease in the mortality rate in WT animals. A mortality rate of 91.7% was observed in TNF-RI(-/-) mice after CLP. This mortality rate was reduced to 37.5% by the application of DHEA. In sham-operated TNF-RI(-/-) animals, a significantly higher proportion of NK cells within the lymphocyte population was measured compared with the corresponding WT group. After CLP, a significant increase in the percentage cell count of NK cells was recorded in WT mice. Overall, following DHEA application in WT mice, an alteration in the cellular immune response was characterized by a reduction in the percentage counts of CD4(+), CD8(+) and NK cells. In the group of TNF-RI(-/-) mice treated with DHEA, no increase in the percentage cell count of NK cells was observed after CLP. No data for cell analysis were available from the CLP-TNF-RI(-/-) mice treated with saline, due to the high mortality rate in these animals. DHEA reduces the complications of sepsis in a TNF-RI-independent manner. Our study suggests that NK cells are involved in the protective mechanism of DHEA in WT mice. It would therefore seem that DHEA represents a feasible alternative therapy for the dysregulated immune system in sepsis.

Gender affects macrophage cytokine and prostaglandin E2 production and PGE2 receptor expression after trauma1

BACKGROUND

Gender influences morbidity and mortality after injury. Hormonal differences are important; however, the role of prostaglandins as mediators in immune dysfunction relating to gender differences after trauma is unclear. We hypothesized that gender-dependent differences in PGE(2) receptor expression and signaling may be involved in immune-related differences. This study determined prostaglandin receptor subtype (EP1-EP4) expression following injury and determined whether gender differences influence EP receptor expression.

MATERIALS AND METHODS

BALB/c male and female mice (estrus and pro-estrus) (n = 6 per group) were subjected to femur fracture and 40% hemorrhage (trauma) or sham injury (anesthesia). Seven days later, the splenic macrophages were harvested and stimulated with lipopolysaccharide (Escherichia coli serotype O55:B5). After 6 h mRNA samples were collected for EP receptor mRNA expression and at 24 h supernatants were collected for PGE(2), TNF-alpha, and IL-6 production.

RESULTS

The expression of EP2-4 receptors was higher in female pro-estrus mice compared with male mice. EP1 receptor expression was higher in males than pro-estrus females. There was decreased expression of all four receptors after trauma in female estrus compared with control estrus mice. Macrophage PGE(2), TNF-alpha, and IL-6 production was significantly increased in injured female mice compared with female controls but there were no differences in injured male mice compared with male controls. PGE(2) and TNF-alpha production by traumatized male mice were significantly less than that produced by traumatized pro-estrus females.

CONCLUSIONS

These data suggest gender-related differences in response to traumatic injury and that alterations in specific EP receptor subtypes may be involved in immune dysfunction after injury. Studies to evaluate targeted modulation of these receptor subtypes may provide further insights to gender-specific differences in the immune response after injury.

BLUNT CHEST TRAUMA INDUCES DELAYED SPLENIC IMMUNOSUPPRESSION

Severe blunt chest trauma is frequently associated with multiple organ failure and sepsis. Posttraumatic immunosuppression seems to play a major role in their development. However, the immunologic alterations following pulmonary contusion are insufficiently elucidated. Specifically, it remains unknown whether immunocompetent cells located distant from the site of the impact are affected. We therefore aimed to characterize the influence of pulmonary contusion on lymphocytes and splenic macrophages. Male C3H/HeN mice (n = 8-10/group) were anesthetized and subjected to trauma or sham procedure. Blunt chest trauma was induced by a blast wave focused on the thorax. Two or 24 h later, splenocytes and splenic macrophages were isolated and stimulated for 48 h. The cytokine release (IFN-gamma, IL-2, IL-3, IL-10, IL-12, IL-18) from splenocytes as well as from splenic macrophages (TNF-alpha, IL-10, IL-12, IL-18) and plasma levels of TNF-alpha and IL-6 were quantified by ELISA. The results indicate that at 2 h after blunt chest trauma, plasma TNF-alpha and IL-6 were markedly increased. At the same time, no differences in splenocyte cytokine production were detectable. However, at 24 h a significantly depressed cytokine release was observed in trauma animals. Furthermore, splenic macrophages showed a significantly decreased production of TNF-alpha, IL-10, and IL-12 at 24 h and markedly increased release of IL-18 at 2 h after trauma. These results indicate that blunt chest trauma causes severe immunodysfunction of lymphocytes and splenic macrophages. Thus, lung contusion as a localized type of trauma causes dysfunction of immunocompetent cell populations, which are located distant from the site of injury.

Estrogen replacement, aging, and cell-mediated immunity after injury

We recently demonstrated that aged mice are less likely to survive following traumatic injury and are more immunosuppressed than young mice who sustain comparable injuries. Immunosuppression in severely injured patients and in rodent models of burn injury is associated with a marked elevation in proinflammatory cytokines, including interleukin-6 (IL-6). We reported that after sustaining a moderate-size scald injury, aged mice have higher circulating levels of IL-6 than young, injured mice. As proestrus levels of estrogen have been reported to boost immune responses and attenuate IL-6 production, in the present study, we went on to determine if estrogen replacement in aged female mice restored cellular immunity and proinflammatory cytokine production. After injury, in placebo-treated, aged animals, there was a >75% suppression in the delayed-type hypersensitivity response relative to placebo-treated, sham-injured, aged mice (P<0.05). In contrast, estrogen supplementation before injury yielded a partial recovery in this response, such that the mice were suppressed by only 40% relative to sham-injured, aged mice (P<0.05). There was a fourfold increase in the circulating level of IL-6 in burn-injured, aged mice who received placebo hormone replacement relative to sham-injured mice given placebo (P<0.05). This level of cytokine was lowered by nearly 50% in aged, estrogen-treated mice. Most remarkably, estrogen replacement improved survival from 42% (in the absence of estrogen) to 70% in aged, burn-injured mice. Further investigation will be needed to determine if age- and gender-specific therapies are needed for the treatment of all trauma patients.

The Impact of Major Trauma: Quality-of-Life Outcomes Are Worse in Women than in Men, Independent of Mechanism and Injury Severity

BACKGROUND

The importance of gender differences in quality of life and psychologic morbidity after major trauma is a newly recognized focus of trauma outcomes research. The Trauma Recovery Project is a large, prospective, epidemiologic study designed to examine multiple outcomes after major trauma, including quality of life (QoL), and psychologic sequelae such as depression and early symptoms of acute stress reaction (SASR). The specific objectives of the present report are to examine gender differences in QoL outcomes and the early incidence of combined depression and SASR after injury, controlling for injury severity, specific body area injured, and mechanism.

METHODS

Between December 1, 1993, and September 1, 1996, 1,048 eligible trauma patients triaged to four participating trauma center hospitals in the San Diego Regionalized Trauma System were enrolled in the study. The enrollment criteria for the study included age 18 years and older, admission Glasgow Coma Scale score of 12 or greater, and length of stay greater than 24 hours. QoL outcome after trauma was measured after injury using the Quality of Well-being scale, a sensitive index to the well end of the functioning continuum (range, 0 = death to 1.000 = optimum functioning). Depression was assessed using the Center for Epidemiologic Studies scale. SASR was assessed using the Impact of Events scale. Patient outcomes were assessed at discharge and at 6, 12, and 18 months after discharge.

RESULTS

Women (n = 313) were significantly more likely to have poor QoL outcomes at follow-up than men (n = 735) (women vs. men: 12-month follow-up odds ratio [OR] = 2.2, p < 0.001; 18-month follow-up OR = 2.0, p < 0.001). Quality of Well-being scores at each of the 6-, 12-, and 18-month follow-up time points were markedly and significantly lower in women compared with men, independent of injury severity, serious and moderate injury status, lower extremity injury, intentional or unintentional injury type, and blunt or penetrating injury. Women were also significantly more likely to develop early combined depression and SASR at discharge (OR = 1.7, p < 0.01) and to have continuous depression throughout the 18-month follow-up period (OR = 2.3, p < 0.001).

CONCLUSION

These analyses provide further important and more detailed evidence that women are at risk of worse QoL outcomes and early psychologic morbidity after major trauma than men, independent of mechanism and injury severity. A better understanding of the impact of major trauma in men and women will be an important component of efforts to improve trauma care and long-term outcome in mature trauma systems.

Differential effects of estrogen in the injured forebrain of young adult and reproductive senescent animals

Estrogen attenuates neural damage resulting from a variety of experimental injury models in adult female rats. To determine whether estrogens neuroprotective actions are age-specific, the present study compared the effects of estrogen on young adult and reproductive senescent animals subject to excitotoxic injury to the forebrain. NMDA was injected bilaterally into the olfactory bulbs of estrogen and placebo-replaced young adult and reproductive senescent animals. Lysates of the olfactory bulb and its basal forebrain afferent, the horizontal limb of the diagonal band of Broca (hlDBB), harvested 24h later were analyzed for expression of IL-1beta, IL-10, and nerve growth factor (NGF). NMDA injections resulted in local activation of microglia and an increase in IL-1beta. Estrogen replacement decreased IL-1beta expression in young adult females, but paradoxically enhanced its expression in reproductive senescent females. Furthermore, bulb injury increased IL-1beta production in the hlDBB of reproductive senescent animals although estrogen replacement was able to suppress lesion-induced expression of this cytokine. In both, the olfactory bulb and hlDBB, constitutive expression of the anti-inflammatory cytokine IL-10 was significantly higher while that of NGF was almost 50% lower in senescent animals as compared to young adults, indicating that aging preferentially altered Th2-type secretions. The present findings are consistent with our earlier observations that estrogen does not exert trophic effects in the aging forebrain and supports the hypothesis that estrogen treatment to reproductive senescent females may exacerbate neural injury.

Androgen-mediated modulation of macrophage function after trauma-hemorrhage: central role of 5alpha-dihydrotestosterone

Androgens have been implicated as the causative factor for the postinjury immune dysfunction in males; however, it remains unknown whether androgens directly affect macrophages. To study this, male mice were sham operated or subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (mean arterial pressure, 30 +/- 5 mmHg for 90 min and then resuscitated). The mice received the 5alpha-reductase inhibitor 4-hydroxyandrostenedione (4-OHA) before resuscitation. Plasma TNF-alpha, IL-6, and IL-10 levels were elevated after trauma-hemorrhage and normalized by 4-OHA. TNF-alpha and IL-6 production by splenic macrophages was decreased after injury, whereas Kupffer cell production of these mediators was enhanced. 4-OHA normalized cytokine production. Androgens suppressed cytokine production by splenic macrophages from hemorrhaged mice, whereas it enhanced TNF-alpha and IL-6 production by Kupffer cells. The addition of 4-OHA in vitro normalized cytokine production by cells treated with testosterone, but it had no effect on dihydrotestosterone-treated cells. These results indicate that androgens directly affect macrophage function in males after trauma and hemorrhagic shock and that the intracellular conversion of testosterone to dihydrotestosterone is of particular importance in mediating the androgen-induced effects.

Failure of monocytes of trauma patients to convert to immature dendritic cells is related to preferential macrophage-colony-stimulating factor-driven macrophage differentiation

Following trauma, increased inflammatory monokine activation and depressed APC function can occur simultaneously. These contradictory monocyte (Mphi) dysfunctions could result if postinjury Mphi differentiation preferentially favored inflammatory macrophage (Mac) differentiation over development into the most potent APC, dendritic cells (DC). In this report, Mphi of trauma patients with a depressed MLR induction capacity are, for the first time, shown to be unable to differentiate in vitro to immature CD1a(+) DC under the influence of GM-CSF and IL-4. Trauma patient Mphi that retained MLR-inducing capacity had a nonsignificant reduction in DC differentiation capacity. Only patient Mphi populations with depressed differentiation to immature DC (iDC) demonstrated depressed IL-12 and IL-15 production and a continued reduced MLR induction capacity. Neither increased IL-10 production nor decreased CD11c(+) DC precursor numbers correlated with depressed Mphi-to-DC differentiation. Instead, these patients' APC-dysfunctional Mphi populations had increased expression of inflammatory Mac phenotypes (CD64(+), CD86(low), HLA-DR(low)) and up-regulated secretion of M-CSF. M-CSF combined with IL-6 inhibits Mphi-to-iDC differentiation and promotes Mphi-to-Mac differentiation by down-regulating GM-CSFR expression and increasing DC apoptosis. Both depressed GM-CSFR expression and increased Mphi iDC apoptosis, as well as increased expression of CD126 (IL-6R) and CD115 (M-CSFR), were detected in APC-defective patient Mphi. In vitro addition of anti-M-CSF enhanced the IL-4 plus GM-CSF-induced Mphi-to-DC differentiation of these patients. This suggests that, in trauma patients, enhanced Mphi-to-Mac differentiation with concomitant inhibited iDC development is partially due to increased circulating Mphi sensitivity to and production of M-CSF and contributes to postinjury immunoaberrations.

Depressed interleukin-12-producing activity by monocytes correlates with adverse clinical course and a shift toward Th2-type lymphocyte pattern in severely injured male trauma patients

OBJECTIVE

To determine the effect of major trauma on the cytokine-producing activity of monocytes and CD4+ T cells in a homogeneous cohort of patients as well as to determine the relationship between monocyte and T-lymphocyte responses and clinical outcome.

SETTINGS

Surgical intensive care units of a trauma center and flow cytometry and experimental laboratories at a teaching hospital.

DESIGN

Prospective cohort clinical study with measurements of white cell cytokine-producing activity on days 2, 5, and 10 postinjury. The number of cytokine-producing CD14+ monocytes, CD4+, and CD8+ T cells were determined in whole blood using flow cytometry combined with the intracellular cytokine staining method. Basal and lipopolysaccharide-stimulated interleukin (IL)-12, tumor necrosis factor-alpha, IL-6, and IL-1alpha production by monocytes as well as basal and phorbol 12-myristate 13-acetate plus ionomycin-stimulated interferon-gamma, IL-4, and tumor necrosis factor-alpha production by T cells were determined on days 2, 5, and 10 postinjury and compared with similar measurements made in healthy control subjects.

PATIENTS

Twelve randomly selected black, male patients were enrolled in the study: mean injury severity score, 26; mean age, 35 yrs; mean Glasgow Coma Scale score, 13; systemic inflammatory response syndrome, 92%; sepsis, 42%; bronchial infection, 42%; and adult respiratory distress syndrome 25%.

MAIN RESULTS

After lipopolysaccharide stimulation, the number of IL-12-, tumor necrosis factor-alpha-, IL-1alpha-, and IL-6-producing CD14+ monocytes was 40% to 70% lower in trauma patients on postinjury days 2, 5, and 10 than in healthy control subjects. After phorbol 12-myristate 13-acetate stimulation, the number of IL-4-producing CD4+ cells increased three-fold in the trauma patients compared with healthy control subjects. In contrast, the number of interferon-gamma- or tumor necrosis factor-alpha-producing CD4+ and CD8+ T cells was not different between the patients and control subjects. The Th1/Th2 ratio was significantly lower in patients on all postinjury days than in the control subjects. A statistically significant inverse correlation was found between the number of IL-12-producing monocytes and IL-4-producing CD4+ T cells in trauma patients (p =.007, r2 =.47). This correlation was absent in control subjects. The degree of depressed capacity of monocyte IL-12 production on day 2 postinjury showed a statistically significant correlation with the development of adult respiratory distress syndrome, sepsis, or infections and also with the duration of systemic inflammatory response syndrome and sepsis.

CONCLUSIONS

Major trauma results in an early and marked decrease in monocyte cytokine-producing activity. The trauma-induced depression in IL-12 production by the mononuclear phagocyte system may promote T-cell commitment toward a Th2 pattern early after trauma. The appearance of the Th2 pattern is the result of elevated numbers of IL-4-producing cells without major alterations in T-cell interferon-gamma-producing capacity. The degree of alterations in monocyte and T-cell responses on day 2 postinjury correlates with the development of adverse clinical outcomes and the subsequent duration of the inflammatory response.

Endocrine targets in experimental shock

Modified resuscitation regimens and cytokine blockade/receptor antagonism after trauma have not been successful in decreasing the mortality rates from sepsis in trauma patients; therefore, an alternative approach using endocrine targets as modulators or inhibitors may be useful. Information regarding the influence of gender and hormones on immune and cardiovascular responses after nonthermal trauma-hemorrhagic shock is, on the one hand, considerable but, on the other hand, disappointingly incomplete. Trauma-hemorrhagic shock produces gender dimorphic immune and cardiovascular responses; men exhibit cardiovascular depression and are immunosuppressed, whereas proestrus women do not show cardiovascular or immunologic depression under those conditions. Furthermore, experimental studies have demonstrated the use of hormones, hormone antagonists, sex steroids, and receptor antagonists as salutary adjuncts, without any adverse effects on gastrointestinal, hepatic, and renal functions, for restoring the depressed immune and cardiovascular responses after trauma-hemorrhage. Thus, flutamide, dehydroepiandrosterone, metoclopramide, and 17beta-estradiol, which are readily availably clinically and do not produce any adverse hemodynamic effects, appear to be safe and novel agents/hormones for the treatment of immune and cardiovascular depression after severe blood loss in male and female trauma victims.

Advanced age negatively influences mesenteric lymph node T cell responses after burn injury

While the pathophysiology of burn injury is well established in young adults, the factors that contribute to pathogenesis and increased death in elderly burn patients are not defined. The purpose of this study is to determine the effects of burn injury on mesenteric lymph node (MLN) T cell responses in young and aged mice. MLN is a cluster of lymph nodes that drains various parts of the intestine and is known to play role in clearance bacteria originating from the intestinal lumen. Results presented here suggest a significant suppression in Con A-induced MLN cell proliferation and IL-2 production in uninjured aged mice compared with uninjured young mice. Following 24 h after injury, although, a significant decrease in lymph node cell proliferation and IL-2 production was observed in both young and aged mice compared with their respective sham-injured animals, the suppression was more in aged mice. In addition we found a reduction in IFN-gamma, a Th-1 cytokine by MLN T cells from aged burned mice relative to young burn (P<0.05) or sham-injured mice (P<0.01). The Th-2 cytokine IL-4, on the other hand, was significantly increased in both young and aged burn-injured mice MLN T cells compared with their respective sham-injured mice. These results show that burn injury causes a greater suppression in MLN T cells ability to proliferate and a more pronounced shift to Th-2 phenotype in aged mice as compared with young mice. Such decreases in T cell functions may impair MLN's ability to clear the bacterial pathogens originating from intestine and thereby contribute to increased pathogenesis in injured host.

Aging enhances lymphocyte cytokine defects after injury

Mortality and sepsis after a traumatic injury is greater in the elderly than in young individuals. The altered lymphocyte response observed to occur in healthy aged individuals is proposed to be a contributing factor to increased mortality. The immune response associated with the increased mortality was explored using a murine scald injury model. In the absence of injury, aged mice had depressed delayed-type hypersensitivity (DTH) and splenocyte proliferative responses relative to young mice. There was also an increase with age in the production of the TH2 cytokines interleukin (IL)-4 and IL-10 by splenocytes. There was no change in the TH1 cytokines IFNgamma or IL-12 with age. However, IL-2 production was significantly lower. Following injury, there was a further decrease in the DTH response of aged injured mice, compared with aged sham mice. In addition, there was a decrease in all of the cytokines examined, regardless of age. In contrast, IFNgamma and IL-2 were significantly lower in the aged injured animals compared with the young injured animals. These results suggest that the lack of an adequate amount of TH1 cytokines shortly after injury in the aged mice may parallel the increased incidence of sepsis and death that occurs in aged burn patients.

Effects of age on mortality and antibiotic efficacy in cecal ligation and puncture

The incidence and mortality of sepsis increase with age, consequently, 80% of the clinical mortality from sepsis occurs in patients over age 65. Despite this aged clinical population, most research models of sepsis use 6- to 16-week-old mice as patient surrogates. This age range of mice corresponds to human ages 10 to 17 years. To assess the influence of age on rodent CLP and on antibiotic therapy, we studied young (4 month), mature (12 month), and aged (24 month) mice. Male C57BL/6 mice (n = 27-30 in each age group) were subjected to cecal ligation and puncture (CLP), two punctures with a 25-gauge needle. Mice were observed untreated for 10 days. Young mice had 20% mortality, mature mice had 70% mortality (P = 0.0013 vs. young), and aged mice had 75% mortality (P = 0.0001 vs. young). To assess the effects of age on antibiotic therapy, mice were subjected to CLP as above (n = 38-40 in each age group). Mice were then randomized to treatment with intraperitoneal injections of ceftriaxone and metronidazole or normal saline. Therapy was initiated 12 h after CLP, and injections were repeated every 12 h for 7 days. Young mice saw a 56% decrease in mortality from CLP with antibiotic therapy (P = 0.001), and mature mice had a 30% decrease in mortality (P = 0.06). Aged mice saw no benefit from antibiotic therapy. We also compared plasma cytokine levels between young and aged mice after CLP. When compared with young mice, aged mice had higher levels of IL-6 and TNF-alpha 24 h after CLP. However, high IL-6 was predictive of mortality at any age. Mice appear to have age-dependent responses to intra-abdominal sepsis and to appropriate therapy.

The association between gender and mortality among trauma patients as modified by age

BACKGROUND

Several studies have reported a null association between gender and mortality after traumatic injury, whereas others found an age-specific association between male gender and increased mortality. Relatively small sample sizes may have contributed to the heterogeneity among existing studies; therefore, a large-sample-size study was undertaken.

METHODS

The National Trauma Data Bank was queried, yielding data for over 150,000 patients involved in blunt or penetrating trauma. Crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the association between gender and mortality, both overall and according to mechanism of injury and age categories.

RESULTS

Among those who sustained blunt trauma, male patients had a significant increase in the risk of death compared with female patients (OR, 1.49; 95% CI, 1.39-1.59) that was most apparent for those > or = 50 years of age (OR, 1.97; 95% CI, 1.84-2.11). For penetrating trauma patients, essentially no significant association, either overall (OR, 1.03; 95% CI, 0.91-1.17) or by age category, was apparent.

CONCLUSION

This study found an association between gender and mortality among blunt trauma patients, particularly those aged > or = 50 years. Animal studies demonstrate that the sex hormones influence the inflammatory response to injury. These results may highlight the importance of sex hormones in traumatic injury outcomes.

Immunoprotection in proestrus females following trauma-hemorrhage: the pivotal role of estrogen receptors

Immune responses in proestrus females are not altered after trauma-hemorrhage, whereas they are markedly depressed in males. Elevated levels of female sex steroids appear to be responsible for maintaining immune responses but it remains unknown, whether estrogen per se is responsible. To study this, proestrus female C3H/HeN mice were subjected to laparotomy (i.e., soft tissue trauma) and hemorrhagic shock (35+/-5 mmHg for 90 min, then resuscitated) or sham operation and received the estrogen receptor antagonist EM-800 or vehicle during resuscitation. Two hours following trauma-hemorrhage, splenocyte proliferation, IL-2, IL-3, IFN-gamma release, and splenic macrophage IL-6 release was maintained in vehicle-treated females. In EM-800-treated females, however, these immune parameters were significantly depressed. Following trauma-hemorrhage, Kupffer cell TNF-alpha release and circulating TNF-alpha were increased only in EM-800-treated females. These findings indicate that the ability of proestrus females to maintain immune function following trauma-hemorrhage is estrogen-dependent and mediated via estrogen receptors.

Sex differences in infection and sepsis

Sex and gender-based differences in responses to infection and sepsis are evident. Estrogens increase immune function, sometimes to the point of inducing autoimmune disease. Testosterone suppresses immune function, sometimes leading to a worsened outcome following traumatic injury. Therapies using sex hormones to improve outcomes after sepsis and hemorrhagic shock and to reduce exacerbations of autoimmune diseases are being studied. Differences in sex hormone levels may not tell the whole story. Studies of immune function in girls and boys before puberty may be helpful. Differences found early might indicate that factors other than estrogen and androgen levels are contributing. Variations in societal role acculturation and exposures that are gender based also may be involved. Clinicians must consider sex and gender when attempting to determine the risk of infection, sepsis, and immune dysfunction in populations. Clinical applications of sex and gender differences are just beginning to occur with the genesis of sex hormone-based treatments. The large-scale efficacy of such treatments has yet to be reported. Innovative strategies based on sex or gender differences in immune responses may soon be available and may lead to essential data for clinical decision making. The impact of sex and gender differences on long-term health outcomes remains to be seen.

Age-related gender differential in outcome after blunt or penetrating trauma

Although laboratory studies indicate that female rodents better tolerate the deleterious consequences of trauma and have higher survival rates than male rodents, it remains unclear whether a similar gender dimorphic pattern is evident in humans. In view of this, the association between gender and mortality in trauma patients admitted to a University Level I Trauma Center was assessed. All adult patients admitted to the University of Alabama at Birmingham Trauma Center with blunt or penetrating injury between July 1996 and March 2001 were selected for analysis. Patients were categorized by mechanism (blunt or penetrating), and odds ratios (ORs) were used to compare the risk of death among males compared with females. The ORs were stratified according to age and were adjusted for demographic, medical, and injury characteristics. Male blunt trauma patients <50 years old had a 2.5 times (95% CI 1.3-4.9) higher risk of death than females; however, for those > or = 50 years old, a smaller, nonstatistically significant difference was apparent (OR 1.4, 95% CI 0.8-2.3). Conversely, for penetrating trauma, males <50 years old exhibited an increased yet nonsignificant risk of death (OR 1.8, 95% CI 0.6-5.4), whereas those > or = 50 years old had a survival advantage (OR 0.1, 95% CI 0.02-0.5). Laboratory studies have demonstrated that estrogens are salutary and androgens are detrimental for survival following trauma-hemorrhage. The results of this study suggest that the physiologic pattern of premenopausal adult female sex hormones may provide a survival advantage in blunt trauma patients; however, the converse pattern prevails for the penetrating trauma patients.

Young versus Old: Factors Affecting Mortality After Blunt Traumatic Injury

Advanced age predicts poor outcome after trauma. We have previously demonstrated that prolonged occult hypoperfusion (POH), defined as serum lactic acid >2.4 mmol/L persisting for >12 hours, is also associated with worse outcomes. We hypothesized that older patients—a group with potentially less physiologic reserve—would be at greater risk from POH. Prospective data from adult blunt trauma patients admitted to a surgical/trauma intensive care unit from January 1, 1998 through December 31, 1999 were analyzed. Mortality, POH, Injury Severity Score (ISS), chronic health designation (CH) from the Acute Physiology and Chronic Health Evaluation, emergency department Glasgow Coma Scale score (EDGCS), emergency department systolic blood pressure (EDSBP), and gender were compared between older (>55 years) and younger (<56 years) patients and then between nonsurvivors and survivors within age cohorts. Two hundred sixty-four patients were analyzed: 195 younger and 69 older. Mortality was 8.3 per cent (22/264). Older patients had higher mortality (20.3% vs 4.1%, P < 0.05), higher CH (42.9% ± 1.3 vs 8.4% ± 0.6), lower ISS (22.6 ± 1.5 vs 25.6 ± 0.8, P < 0.05), higher EDGCS (12.9 ± 0.5 vs 10.7 ± 0.4, P < 0.05), and higher EDSBP (141.5 ± 4.1 vs 129.3 ± 2.2). There were no differences in incidence of POH and gender. Within both age cohorts nonsurvivors had higher ISS, lower EDGCS, and higher CH. Older patients with POH had 34.6 per cent mortality as compared with 11.6 per cent for no POH ( P < 0.05). Mortality in younger patients was no different in the presence of POH, and all nonsurvivors were male. Despite lower ISS and higher EDGCS and EDSBP older patients had five times the mortality of younger patients. Age-specific mortality was influenced by POH and gender. POH was associated with higher mortality only in older patients. With less physiologic reserve older patients may not have been able to adequately compensate for POH; this emphasizes the importance of rapidly correcting serum lactic acid as an endpoint in resuscitation in this population.

Sexual dimorphism in the spontaneous recovery from spinal cord injury: a gender gap in beneficial autoimmunity?

Immune cells have been shown to contribute to spontaneous recovery from central nervous system (CNS) injury. Here we show that adult female rats and mice recover significantly better than their male littermates from incomplete spinal cord injury (ISCI). This sexual dimorphism is wiped out and recovery is worse in adult mice deprived of mature T cells. After spinal cord contusion in adult rats, functional recovery (measured by locomotor scores in an open field) was significantly worse in females treated with dihydrotestosterone prior to the injury than in placebo-treated controls, and significantly better in castrated males than in their noncastrated male littermates. Post-traumatic administration of the testosterone receptor antagonist flutamide promoted the functional recovery in adult male rats. These results, in line with the known inhibitory effect of testosterone on cell-mediated immunity, suggest that androgen-mediated immunosuppression plays a role in ISCI-related immune dysfunction and can therefore partly explain the worse outcome of ISCI in males than in female. We suggest that females, which are more prone to develop autoimmune response than males, benefit from this response in cases of CNS insults.

Gender differences in mortality following burn injury

Clinical and experimental studies have demonstrated higher mortality following nonthermal trauma among males compared with females. To date, few clinical retrospective studies have focused on gender differences in outcome following burn injury with respect to age. All patients admitted to the University of Alabama at Birmingham (UAB) Burn Center between January 1994 and December 2000 were selected for inclusion in the study. Gender differences in demographic, clinical, and outcome characteristics were compared. Unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the association between mortality and gender, both overall and stratified by age. Over the 7-year study period, 1229 males and 382 females were admitted to the UAB Burn Center, and mortality rates were 7.2% and 13.4%, respectively (P = 0.0002). Female patients were more likely to be older, of the black race, and in poorer health. In addition, females were more likely to suffer flame and scald burns. The association between mortality and gender was modified by age. Up to age 60, mortality rates among females were over twice that of males (OR 2.3, 95% Cl 1.4-3.8); however, no difference was noted among those 60 and older (OR 0.9, 95% Cl 0.5-1.6). These associations persisted following adjustment for potentially confounding variables. Causes and timing of death were similar for males and females. Women less than 60 years of age who sustain burn injuries have an increased risk of death compared with males. Differences in the natural history of nonthermal trauma and burn injury may provide insight regarding these divergent findings.

The c-Jun N-terminal kinases in cerebral microglia: immunological functions in the brain

The c-Jun N-terminal kinases (JNKs) exert a pleiotrophy of physiological and pathological actions. This is also true for the immune system. Disruption of the JNK locus results in substantial functional deficits of peripheral T-cells. In contrast to circulating immune cells and the role of p38, the presence and function of JNKs in the immune cells of the brain remain to be defined. Here, we report on the expression and activation of JNKs in cultivated microglia from neonatal rats and from mice with targeted disruption of the JNK locus and the N-terminal mutation of c-Jun (c-JunAA), respectively. JNK1, 2 and 3 mRNA and proteins were all expressed in microglia. Following stimulation with LPS (100 ng/mL), a classical activator of microglia, JNKs were rapidly activated and this activation returns to basal levels within 4 hr. Following LPS and other stimuli such as thrombin (10-50 unit/mL), the activation of JNKs went along with the N-terminal phosphorylation of c-Jun which persisted for at least 8 hr. Indirect inhibition of JNK by CEP-11004 (0.5-2 microM), an inhibitor of mixed-lineage kinases (MLK), reduced the LPS-induced phosphorylation of both, JNK and c-Jun, by around 50%, and attentuated the LPS-induced the alterations in microglial morphology. Finally, JNKs are involved in the control of cytokine release since both, incubation with CEP-11004 and disruption of the JNK1 locus enhanced the release of TNFalpha, IL-6 and IL-12. Our findings provide insight in so far unknown functions of JNKs in cerebral immune cells. These observations are also important for the wide spread efforts to develop JNK-inhibitors as neuroprotective drugs which, however, might trigger pro-inflammatory processes.

Androgen- and estrogen-dependent sex differences in host resistance to Strongyloides venezuelensis infection in Wistar rats

The effects of male and female sex hormones on the protective capacity of Wistar rats against infection with Strongyloides venezuelensis were investigated. Male rats were more susceptible than females in terms of worm recovery from the lungs. Orchidectomy of male animals significantly reduced the plasma testosterone concentration and increased host resistance to the migratory stages of S. venezuelensis larvae. In contrast, ovariectomy of female animals significantly decreased host resistance in association with a significant reduction of estrogen levels. To examine the direct effect of sex hormones, exogenous testosterone and estrogen were implanted into animals. Susceptibility significantly increased or decreased in ovariectomized females given testosterone or estrogen, respectively. These results suggest that male and female sex hormones are important in the down- and up-regulation of host resistance against S. venezuelensis in Wistar rats.

Can the interleukin-6 response to endotoxin be predicted? Studies of the influence of a promoter polymorphism of the interleukin-6 gene, gender, the density of the endotoxin receptor CD14, and inflammatory cytokines

OBJECTIVES

To evaluate whether the -174 G/C promoter polymorphism of the interleukin-6 gene, gender, the monocyte density of the endotoxin receptor CD14, or the inflammatory cytokines tumor necrosis factor-alpha or interleukin-1beta influence the interleukin-6 response of whole blood to endotoxin.

DESIGN

Analysis of interleukin-6 release from endotoxin-stimulated human whole blood.

SETTING

Medical research laboratory.

PATIENTS

Healthy human blood donors.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The interleukin-6 -174 G/C and the tumor necrosis factor -308 G/A promoter polymorphisms were determined by real-time polymerase chain reaction assay by using specific fluorescence labeled hybridization probes. Monocyte CD14 expression was assessed by flow cytometry. After incubation of whole blood with endotoxin, plasma concentrations of interleukin-6, tumor necrosis factor-alpha, and interleukin-1beta were measured by means of chemiluminescence. The interleukin-6 concentrations were lower (p = .005) in individuals who were CG heterozygotes compared with individuals homozygous for the C or the G. The difference between C and G homozygotes was not significant (p = .67). The interleukin-6 response was enhanced in men compared with women (p = .015). There was no correlation between interleukin-6 concentrations and monocyte CD14 density. Interleukin-6 concentrations correlated with the concentrations of tumor necrosis factor-alpha (r = .59, p = .01) and interleukin-1beta (r = .47, p = .01). There was no linkage between the tumor necrosis factor -308 and the interleukin-6 -174 polymorphisms.

CONCLUSIONS

The interleukin-6 response to endotoxin was influenced by gender and correlated with the concentrations of more proximal cytokine tumor necrosis factor-alpha and interleukin-1beta. The interleukin-6 -174 G/C promoter polymorphism can only partly predict the interleukin-6 response of human whole blood to endotoxin stimulation, and the results were different from previous reporter gene assays that reported higher interleukin-6 concentrations for the G allele. Tumor necrosis factor -308 G homozygotes produce the lowest tumor necrosis factor concentrations. The number of tumor necrosis factor -308 G homozygotes was not higher among interleukin-6 -174 heterozygotes, and thus this cannot account for their significantly smaller interleukin-6 production.

Postinjury malaria: a study of trauma victims in cambodia

BACKGROUND

The pattern of host defense against plasmodium is comparable to the immune response to bacterial infection. Posttraumatic immunosuppression may therefore cause relapses of malaria secondary to trauma and trauma surgery in asymptomatic carriers of the parasites in endemic areas. To our knowledge this has not been validated in epidemiologic studies.

METHODS

Postinjury malaria was registered retrospectively in 342 land mine and war victims from malaria-endemic areas in Cambodia. The incidence rate was analyzed in terms of age, gender, preinjury endemicity, evacuation times, anatomic injury severity, systolic blood pressure at admission, blood transfusion, and duration of the first surgical intervention as independent variables.

RESULTS

The rate of postinjury malaria in the study patients was 33.3% (95% CI, 28.3-38.3%). Injury Severity Score (ISS) and surgical operation time were risk factors (area under the curve in receiver operating characteristic plots were 0.73 and 0.79, respectively). The impact of the other risk factors was nonsignificant.

CONCLUSION

Despite difficulties in diagnosing postoperative malaria in endemic areas, the study demonstrates that the rate of postinjury malaria is high. The results legitimate controlled trials of immediate postinjury chemoprophylaxis to severely injured in endemic areas. The authors recommend staged surgical operations with brief primary interventions in victims with severe injuries.

Interleukin-8 release during early reperfusion predicts graft function in human lung transplantation

Cytokines have been shown to play an important role in promoting inflammation in the setting of ischemia-reperfusion injury. However, their role in human lung transplantation has not been systematically explored. This study was undertaken to examine the kinetics of cytokine release in 18 consecutive human lung transplantation procedures and to examine the relationships between their levels and donor factors, length of ischemic time, and allograft function. TNF-alpha, IFN-gamma, IL-10, IL-12, and IL-18 were found at higher levels during the ischemic time, whereas IL-8 predominantly increased after reperfusion. IL-8 levels after 2 h of reperfusion correlated with lung function assessed by the Pa(O2 )/FI(O(2)) ratio, the mean airway pressure, and the APACHE score during the first 24 postoperative hours. The length of ICU stay also correlated with IL-8 levels after 2 h of reperfusion. Longer ischemic time was associated with significantly higher levels of IL-18 before reperfusion, and older donors had significantly lower levels of IL-10 after reperfusion. We have demonstrated the importance of IL-8 in predicting early graft function after human lung transplantation. In addition, we showed that donor age and ischemic time may influence release of specific cytokines during ischemia-reperfusion.

Female sex hormones regulate macrophage function after trauma-hemorrhage and prevent increased death rate from subsequent sepsis

OBJECTIVE

To determine whether reduction of circulating female sex hormones by ovariectomy causes suppression of macrophage (Mphi) function after trauma-hemorrhage and increases susceptibility to subsequent sepsis.

SUMMARY BACKGROUND DATA

Studies indicate that immune functions are markedly depressed in males but not in proestrus females after trauma-hemorrhage. Although male sex steroids are immunosuppressive, it remains unknown whether female sex hormones are immunoprotective after trauma-hemorrhage.

METHODS

Circulating female sex hormones were reduced by ovariectomy of 8-week-old female CBA/J mice. Two weeks afterward, ovariectomy and proestrus sham-ovariectomy mice were subjected to laparotomy (i.e., soft tissue trauma) and hemorrhagic shock (35 +/- 5 mm Hg for 90 minutes, then resuscitated) or sham operation. Two hours afterward, splenic and peritoneal Mphi and Kupffer cells were isolated and cytokine production was assessed. In a second series of experiments, animals were subjected to sepsis by cecal ligation and puncture at 24 hours after trauma-hemorrhage or sham operation, and survival was assessed.

RESULTS

Release of interleukin-1 and interleukin-6 by splenic and peritoneal Mphi from proestrus mice was maintained after trauma-hemorrhage, whereas release of interleukin-1 and interleukin-6 by Mphi from ovariectomized mice was depressed by approximately 50%. In contrast, trauma-hemorrhage resulted in a fourfold increase of Kupffer cell release of tumor necrosis factor-alpha in ovariectomized females and a fivefold increase in plasma concentrations of tumor necrosis factor-alpha. Release of tumor necrosis factor-alpha and plasma concentrations were unchanged in proestrus mice under such conditions. When proestrus and ovariectomized animals were subjected to sepsis by cecal ligation and puncture at 24 hours after trauma-hemorrhage or sham operation, ovariectomized mice had a significantly higher death rate than proestrus mice.

CONCLUSIONS

These findings suggest that female sex hormones play a critical role in maintaining immune responses after trauma-hemorrhage by suppressing the elaboration of tumor necrosis factor-alpha and prevent the increased lethality from subsequent sepsis. Thus, female sex hormones may be a useful adjunct in preventing trauma-induced immunodepression and increased susceptibility to subsequent sepsis.

Relationship between oxidative burst activity and CD11b expression in neutrophils and monocytes from healthy individuals: effects of race and gender

Oxidative burst activity and the expression of adhesion molecules have been used as indicators of leukocyte activation status. The aim of the study was to delineate the relationship of oxidative burst activity and the expression of adhesion molecules in neutrophils and monocytes from a pool of healthy volunteers (n = 96). We also tested the potential role of gender and a racial background in the individual response differences. Basal and phorbol myristate acetate (PMA)-stimulated oxidative burst and CD11b expression were determined using dihydrorhodamine 123 and phycoerythrin (PE)-conjugated anti-CD11b monoclonal antibodies. PMA markedly increased CD11b expression and cellular oxidant content in neutrophils and monocytes in all samples. However, the responses showed considerable variability among individuals. A positive correlation was observed between the responsiveness of neutrophils and monocytes in their basal or PMA-stimulated CD11b expressions and PMA-stimulated oxidative burst activities. In contrast, no correlation was found between the level of adhesion molecule expression and cellular oxidant content in monocytes or neutrophils either under basal or under PMA-stimulated conditions. The reactivity of oxidative burst (i.e., PMA-stimulated over basal) was significantly lower in neutrophils from African American males compared with cells from African American females, white females, or white males. In contrast, reactivity of monocytes was significantly elevated in white males compared with all other groups. These findings indicate that leukocytes with a relatively high degree of adhesion molecule expression may display an average or decreased oxidative burst activity, and vice versa. Our findings also indicate that ethnic background may influence the oxidative burst activity in neutrophils and monocytes. This needs consideration in clinical studies utilizing healthy volunteers with mixed gender and ethnic backgrounds.

Gender differences in the inflammatory response and survival following haemorrhage and subsequent sepsis

Studies have shown gender dimorphism in cell-mediated immune responses following haemorrhage, with depressed responses in young males and maintained or enhanced responses in proestrus females. However, it remains unknown whether or not the sexually dimorphic immune response to haemorrhage provides any protection against a subsequent in vivo polymicrobial septic challenge. To study this, male and proestrus female C3H/HeN mice were subjected to haemorrhage (35+/-5 mmHg for 90 min followed by fluid resuscitation) or sham operation. Twenty-four hours thereafter, all mice were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP) and survival was assessed over a 10 day period. Haemorrhage prior to CLP significantly increased mortality in males as compared to shams. In contrast, mortality in females following CLP was comparable between the sham and haemorrhage groups. Plasma levels of interleukin (IL-)6, tumour necrosis factor (TNF)-alpha and prostaglandin E(2)(PGE(2)) at 5 h after CLP were significantly increased in males subjected to prior haemorrhage. In contrast, plasma levels of IL-6 and TNF-alpha in females did not increase under such conditions. PGE(2)levels were comparable in males and females following CLP, however prior haemorrhage significantly reduced PGE(2)levels in females, whereas no change was observed in males. Liver and splenic expression of cyclooxygenase-2 protein paralleled the changes in plasma PGE(2). Female sex hormones, therefore, appear to play an important role not only in maintaining immune function following haemorrhage, but also provide a survival advantage against subsequent septic challenge.

The importance of gender on outcome after major trauma: functional and psychologic outcomes in women versus men

BACKGROUND

Outcome after major trauma is an increasingly important focus of injury research. The effect of gender on functional and psychological outcomes has not been examined. The Trauma Recovery Project is a large, prospective, epidemiologic study designed to examine multiple outcomes after major trauma, including quality of life, functional outcome, and psychological sequelae such as depression and early symptoms of acute stress reaction. The specific objectives of the present report are to examine gender differences in short- and long-term functional and psychological outcomes in the Trauma Recovery Project population.

METHODS

Between December 1, 1993, and September 1, 1996, 1,048 eligible trauma patients triaged to four participating trauma center hospitals in the San Diego Regionalized Trauma System were enrolled in the study. The enrollment criteria for the study included age 18 years and older, admission Glasgow Coma Scale score of 12 or greater, and length of stay greater than 24 hours. Quality of life was measured after injury using the Quality of Well-being scale, a sensitive index to the well end of the functioning continuum (range, 0 = death to 1.000 = optimum functioning). Depression was assessed using the Center for Epidemiologic Studies Depression scale and early symptoms of acute stress reaction were assessed using the Impact of Events scale. Patient outcomes were assessed at discharge and at 6, 12, and 18 months after discharge.

RESULTS

Functional outcome was significantly worse at each follow-up time point in women (n = 313) versus men (n = 735). Quality of Well-being scale scores were markedly and significantly lower at 6-month follow-up in women compared with those in men (0.606 vs. 0.646, p < 0.0001). This association persisted at 12-month (0.637 vs. 0.6685, p < 0.0001) and 18-month (0.646 vs. 0.6696, p < 0.0001) follow-up. Women were also significantly more likely to be depressed at all follow-up time points (discharge odds ratio [OR] = 1.4, p < 0.05; 6-month follow-up OR = 2.2, p < 0.01; 12-month follow-up OR = 2.0, p < 0.01; 18-month follow-up OR = 2.2, p < 0.01) and to have early symptoms of acute stress reaction at discharge (OR = 1.4, p < 0.05). These differences remained significant and independent after adjusting for injury severity, mechanism, age, and sociodemographic factors.

CONCLUSION

Women are at risk for markedly worse functional and psychological outcomes after major trauma than men, independent of injury severity and mechanism. Gender differences in short- and long-term trauma outcomes have important implications for future studies of recovery from trauma.