Julie K. Cremeans-Smith

Sleep Disruptions Mediate the Relationship Between Early Postoperative Pain and Later Functioning Following Total Knee Replacement Surgery

Despite relatively standardized surgical procedures, patients undergoing total knee replacement (TKR) surgery differ dramatically in the speed of their recovery. Previous research has suggested a relationship between the experience of pain and sleep disruptions among patients with chronic pain or those undergoing surgery, such that more severe pain is associated with more frequent awakenings throughout the night. This study examined sleep disruptions 1 month following surgery as a mediator of the relationship between pain 1 month following surgery and functional limitations 3 months following surgery. A total of 110 patients scheduled to undergo unilateral TKR were examined at three time points: 2–3 weeks prior to surgery, 1 month following surgery, and 3 months following surgery. After controlling for presurgical levels of pain, sleep disruptions, and functional limitations, sleep disruptions 1 month following surgery partially mediated the relationship between pain 1 month following surgery and functional limitations 3 months following surgery. The present findings underscore the importance of adequate sleep during postsurgical recovery and suggest that interventions targeting sleep disruptions may improve the speed and quality of patients’ recovery from TKR and other surgical procedures.

In-hospital levels of C-reactive protein and IL-6 predict post-operative depressive symptoms among patients undergoing total knee replacement surgery

Behavioral changes observed following immune system activation are similar to many of the hallmark symptoms of major depressive disorder (MDD), including appetite change, lethargy, fatigue, negative mood and anhedonia. Acute phase proteins, such as interleukin-6 (IL-6) and C-reactive protein (CRP) have been implicated in the production of sickness behavior, and research has revealed significant differences in the levels of these acute phase proteins between depressed and non-depressed individuals. The current study examined whether early post-operative IL-6 and CRP levels predicted subsequent depressive symptoms in 110 patients undergoing total knee replacement surgery (TKR). In-hospital levels of IL-6 and CRP predicted depressive symptoms at three-months following surgery, as indicated by significant main effects and a significant interaction term. Specifically, lower levels of in-hospital CRP and higher levels of IL-6 in-hospital predicted more depressive symptoms three-months following surgery. The finding that levels of acute phase proteins soon after surgery predict subsequent depressive symptoms, if replicated, extends prior research on the relationships between IL-6, CRP, and depression. Further, this predictive relationship suggests the possibility of early identification of individuals at risk for the subsequent development of post-operative depression.

Symptoms of postsurgical distress following total knee replacement and their relationship to recovery outcomes

OBJECTIVE Prior research has suggested that posttraumatic stress symptoms may occur in the context of medical events. Further, these symptoms are often comorbid with conditions associated with pain. Therefore, the current study examined the occurrence of distress following arthroplastic surgery and the relationship of these symptoms to postoperative recovery. METHODS Patients (N =110) undergoing unilateral, total knee replacement (TKR) surgery were assessed at three time points proximal to their surgery: approximately 2 weeks prior to surgery (T1), 1 month following surgery (T2) and 3 months following surgery (T3). Patients completed survey assessments of recovery outcomes (Western Ontario and McMaster Universities Osteoarthritis Index) and distress (The Impact of Event Scale [IES]) following surgery (T2 and T3). RESULTS A significant percentage (20%) of patients undergoing TKR reported noteworthy levels of postsurgical stress 1 and 3 months following surgery. Further, this distress was associated with a more difficult recovery following TKR, characterized by more severe pain and greater functional limitations. After controlling for potential confounding variables, regression analyses suggested that postsurgical stress was cross-sectionally related to pain perception and longitudinally predicted subsequent functional limitations and global assessments of recovery. DISCUSSION To our knowledge, this is the first study to examine postoperative distress (using the IES) following TKR. The present study adds to the growing body of literature documenting the impact of psychological processes on postoperative recovery.

Zymosan: induction of sickness behavior and interaction with lipopolysaccharide

The yeast particulate zymosan (Zy) activates innate immune system cells and induces cytokine secretion. There is also evidence that Zy can affect biologic responses to bacterial lipopolysaccharide (LPS) and that the pathways by which these two agents act upon immune cells are only partially distinct. The present experiments assessed the ability of Zy to elicit CNS-mediated sickness symptoms and to alter their responses to LPS. In Experiment 1, Zy induced elements of the sickness behavior syndrome dose-responsively in Long-Evans rats, as indicated by reductions in consumption of a highly palatable bait and in body temperature. In Experiment 2, Zy exerted a priming effect, sensitizing animals to subsequent LPS as measured by reductions in bait consumption, 24-h laboratory chow intake, and body temperature. Experiment 3 failed to provide evidence for LPS-to-Zy cross-tolerance but did indicate that the administration of Zy disrupts previously acquired LPS tolerance. These results suggest that the specifics of exposure to microbially derived innate immune activators have to be taken into account in investigating the biologic bases of sickness behaviors and developing models of coinfection.

Predicting symptoms of post-traumatic stress among patients undergoing orthopedic surgery on the basis of routinely collected cardiovascular data

The present study examined whether in-hospital assessments of heart rate and blood pressure predicted symptoms of post-traumatic stress (PTS) in 110 patients undergoing total knee replacement surgery. After controlling for conceptually relevant factors, in-hospital cardiovascular functioning predicted symptoms of PTS three months following surgery. Specifically, lower pre-surgical and post-surgical systolic and diastolic blood pressure predicted more symptoms of avoidance and PTS (total). In contrast, higher heart rate prior to and shortly following surgery predicted marginally more intrusive thoughts. The present findings suggest that routinely collected medical data may provide a means to identify patients at risk for problematic outcomes following surgery.

Physiological Indices of Stress Prior to and Following Total Knee Arthroplasty Predict the Occurrence of Severe Post-Operative Pain

OBJECTIVE The severe pain and disability associated with osteoarthritis often motivate individuals to undergo arthroplastic surgery. However, a significant number of surgical patients continue to experience pain following surgery. Prior research has implicated both the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) in the sensitization of pain receptors and chronic pain conditions. This study uses a prospective, observational, cohort design to examine whether physiological stress responses before and after surgery could predict post-operative pain severity. SUBJECTS Participants included 110 patients undergoing total knee arthroplasty. METHODS Physiological indices of stress included the measurement of catecholamine and cortisol levels in 15-hour urine samples collected prior to and 1 month following surgery, as well as in-hospital heart rate and blood pressure (before and after surgery), which were abstracted from medical records. Patients completed the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [Bellamy et al., J Orthop Rheumatol 1: , 95 (1988)] 2.5 weeks prior to surgery and at a 3-month follow-up. RESULTS Contrary to expectations, lower stress hormone levels at baseline were related to more severe post-operative pain. Data at later time points, however, supported our hypothesis: cardiovascular tone shortly before surgery and urinary levels of epinephrine 1 month following surgery were positively related to pain severity 3 months later. CONCLUSION Results suggest that the occurrence of post-operative pain can be predicted on the basis of stress physiology prior to and following arthroplastic surgery.

Using established predictors of post-traumatic stress to explain variations in recovery outcomes among orthopedic patients

The present studies examine whether information contained in medical records can be used to predict outcomes following two orthopedic procedures: repair of hip fracture and total knee replacement. Study 1 reports the acute, in-hospital recovery data from the medical records of 119 hip fracture patients. Study 2 is a prospective, longitudinal investigation of 3-month postoperative recovery of 110 total knee replacement patients. Patients characterized by a greater number of post-traumatic stress risk factors experienced poorer outcomes following orthopedic surgery. Our results suggest that patients at risk for negative outcomes can be identified by information readily available to medical personnel.

The impact of gender and hypothalamic pituitary adrenal activity on depressive symptoms following surgical stress.

The impact of gender and cortisol levels on depression following planned surgery was examined in 95 men and women. Patients were assessed prior to surgery and at one and three months following surgery. Higher cortisol levels conferred greater risk for depression at one and three months following surgery. This effect was stronger for men than women at one month following surgery, but did not differ between genders at three months post-surgery. Results support a mechanistic role of HPA alterations in depression following a surgical stressor that differs in strength between men and women.

Fear of pain and the frequency with which healthy individuals engage in physical activity

Despite noted health benefits of physical activity, many adults engage in a sedentary lifestyle. The current study examines relationships between fear of pain, expectations regarding physical activity, and frequency of activity engagement among a healthy sample. We hypothesised that individuals with a greater fear of pain would express negative expectations and report less frequent engagement in physical activity. Participants were 162 undergraduate students who completed surveys assessing the aforementioned variables, as well as depressive symptoms and general health. We report herein that fear of pain was related to expectations regarding physical activity, which in turn predicted the frequency of activity engagement. These relationships differed by gender, such that fear of pain was negatively related to females’ perceived benefits but positively related to males’ frequency of exercise. Based on the current findings, we suggest that interventions aimed at reducing fear of pain may be particularly successful in addressing cognitive factors influencing females’ participation in physical activity.

Interpersonal Pain Dynamics in Couples: Interactions Between Spouses’ Physical Health Predict Caregiver Outcomes

Pain is a private experience which patients may express through verbal or behavioral means. The communication of such suffering can result in the individual’s pain potentially becoming a social stressor. Patients’ verbal or nonverbal pain behaviors may elicit social support from others, frequently including their spouse. In high quality marriages, spouses engage in shared efforts to cope with the stress of one partner’s painful condition. However, prior research on the interpersonal dynamics of pain among couples has focused on the impact of one partner’s health condition while ignoring the potential that both spouses may be coping with a chronic health condition. Congruence frequently occurs between marital partners in respect to health behaviors and diagnoses. Herein, the interactions between the physical health of 101 older women with osteoarthritis and their caregiving husbands are considered. Results illustrate significant interactions between spouses’ physical health, which predict the behavior and mental health of the caregiving spouse. Further, husbands’ provision of emotional support and depressive symptoms are influenced by actor effects, while provision of instrumental support and life satisfaction are associated with partner effects. Therefore, future research on interpersonal dynamics of pain within married couples should consider the health status of both spouses.