Distinguishing problematic from nonproblematic postsurgical pain: A pain trajectory analysis after total knee arthroplasty

The goal of this study was to follow a cohort of patients undergoing total knee arthroplasty over time to: (1) identify and describe the various pain trajectories beginning preoperatively and for up to 12 months after surgery, (2) identify baseline predictors of trajectory group membership, and (3) identify trajectory groups associated with poor psychosocial outcomes 12 months after surgery. One hundred seventy-three participants (female = 85 [49%]; mean age [years] = 62.9, SD = 6.8) completed pain and psychological questionnaires and functional performance tests preoperatively and 4 days, 6 weeks, and 3 and 12 months after total knee arthroplasty. Using growth mixture modeling, results showed that a 4-group model, with a quadratic slope and baseline pain data predicting trajectory group membership, best fit the data (Akaike information criterion = 2772.27). The first 3 pain trajectories represent various rates of recovery ending with relatively low levels of pain 12 months after surgery. Group 4, the constant high pain group, comprises patients who have a neutral or positive pain slope and do not show improvement in their pain experience over the first year after surgery. This model suggests that preoperative pain levels are predictive of pain trajectory group membership and moderate preoperative pain, as opposed to low or high pain, is a risk factor for a neutral or positive pain trajectory postoperatively. Consistent with previous studies, these results show that postoperative pain is not a homogeneous condition and point to the importance of examining intraindividual pain fluctuations as they relate to pain interventions and prevention strategies.M. G. Page´ is supported by a Canada Graduate Scholarship— Doctoral Award from the Canadian Institutes of Health Research (CIHR) and is a recipient of a Lillian-Wright Maternal-Child Health Scholarship from York University, a trainee member of Pain in Child Health and a CIHR Strategic Training Fellow in Pain: Molecules to Community. J. Katz is supported by a CIHR Canada Research Chair in Health Psychology at York University. H. A. Clarke is supported by a Merit Award from the Department of Anaesthesia at the University of Toronto and also supported by the STAGE Training Program in Genetic Epidemiology from the CIHR. The remaining authors have no conflicts of interest to declare

Just how much does it cost? A cost study of chronic pain following cardiac surgery

Objective: The study objective was to determine use of pain-related health care resources and associated direct and indirect costs over a two-year period in cardiac surgery patients who developed chronic post-surgical pain (CPSP). Methods: This multicentric observational prospective study recruited patients prior to cardiac surgery; these patients completed research assistant-administered questionnaires on pain and psychological characteristics at 6, 12 and 24 months post-operatively. Patients reporting CPSP also completed a one-month pain care record (PCR) (self-report diary) at each follow-up. Data were analyzed using descriptive statistics, multivariable logistic regression models, and generalized linear models with log link and gamma family adjusting for sociodemographic and pain intensity. Results: Out of 1,247 patients, 18%, 13%, and 9% reported experiencing CPSP at 6, 12, and 24 months, respectively. Between 16% and 28% of CPSP patients reported utilizing health care resources for their pain over the follow-up period. Among all CPSP patients, mean monthly pain-related costs were CAN$207 at 6 months and significantly decreased thereafter. More severe pain and greater levels of pain catastrophizing were the most consistent predictors of health care utilization and costs. Discussion: Health care costs associated with early management of CPSP after cardiac surgery seem attributable to a minority of patients and decrease over time for most of them. Results are novel in that they document for the first time the economic burden of CPSP in this population of patients. Longer follow-up time that would capture severe cases of CPSP as well as examination of costs associated with other surgical populations are warranted. Summary: Economic burden of chronic post-surgical pain may be substantial but few patients utilize resources. Health utilization and costs are associated with pain and psychological characteristics

Conducting gender-based analysis of existing databases when self-reported gender data are unavailable: the GENDER Index in a working population

Objectives Growing attention has been given to considering sex and gender in health research. However, this remains a challenge in the context of retrospective studies where self-reported gender measures are often unavailable. This study aimed to create and validate a composite gender index using data from the Canadian Community Health Survey (CCHS). Methods According to scientific literature and expert opinion, the GENDER Index was built using several variables available in the CCHS and deemed to be gender-related (e.g., occupation, receiving child support, number of working hours). Among workers aged 18–50 years who had no missing data for our variables of interest (n = 29,470 participants), propensity scores were derived from a logistic regression model that included gender-related variables as covariates and where biological sex served as the dependent variable. Construct validity of propensity scores (GENDER Index scores) were then examined. Results When looking at the distribution of the GENDER Index scores in males and females, they appeared related but partly independent. Differences in the proportion of females appeared between groups categorized according to the GENDER Index scores tertiles (p < 0.0001). Construct validity was also examined through associations between the GENDER Index scores and gender-related variables identified a priori such as choosing/avoiding certain foods because of weight concerns (p < 0.0001), caring for children as the most important thing contributing to stress (p = 0.0309), and ability to handle unexpected/difficult problems (p = 0.0375). Conclusion The GENDER Index could be useful to enhance the capacity of researchers using CCHS data to conduct gender-based analysis among populations of workers

Pregabalin reduces postoperative opioid consumption and pain for 1 week after hospital discharge, but does not affect function at 6 weeks or 3 months after total hip arthroplasty

BACKGROUND: This study examined whether a perioperative regimen of pregabalin added to celecoxib improved pain scores and functional outcomes postdischarge up to 3 months after total hip arthroplasty (primary outcome) and acute postoperative pain and adverse effects (secondary outcomes). METHODS: One hundred and eighty-four patients were enrolled in a randomized, double-blind, placebo-controlled study. Two hours before receiving a spinal anaesthetic and undergoing surgery, patients received celecoxib 400 mg p.o. and were randomly assigned to receive either pregabalin 150 mg p.o. or placebo p.o. After surgery, patients received pregabalin 75 mg or placebo twice daily in hospital and for 7 days after discharge. Patients also received celecoxib 200 mg every 12 h for 72 h and morphine i.v. patient-controlled analgesia for 24 h. Pain and function were assessed at baseline, 6 weeks, and 3 months after surgery. RESULTS: There was no difference between groups in physical function or incidence and intensity of chronic pain 3 months after total hip arthroplasty. The pregabalin group used less morphine [mean (sd): 39.85 (28.1) mg] than the placebo group [54.01 (31.2) mg] in the first 24 h after surgery (P<0.01). Pain scores were significantly lower in the pregabalin group vs the placebo group on days 1-7 after hospitaldischarge, and the pregabalin group required less adjunctive opioid medication (Percocet) 1 week after hospital discharge (P<0.05). CONCLUSIONS: Perioperative administration of pregabalin did not improve pain or physical function at 6 weeks or 3 months after total hip arthroplasty. Perioperative administration of pregabalin decreased opioid consumption in hospital and reduced daily pain scores and adjunct opioid consumption for 1 week after discharge.Department of Anaesthesia at the University of Toronto (Merit Awards to H.C. and C.M.); Canadian Institute of Health Research Fellowship (to H.C.); Canada Research Chair in Health Psychology at York University (to J. Katz); Pfizer Canada (physician-initiated peer-reviewed Neuropathic Pain Competition)

Factorial Validity of the English-Language Version of the Pain Catastrophizing Scale–Child Version

The Pain Catastrophizing Scale (PCS) was developed in English to assess 3 components of catastrophizing (rumination, magnification, helplessness). It has been adapted for use and validated with Flemish-speaking children (Pain Catastrophizing Scale for Children [PCS-C]) and French-speaking adolescents. The PCS-C has been back-translated to English and used extensively in research with English-speaking children; however, the factorial validity of the English PCS-C has not been empirically examined. This study assessed the factor structure of the English PCS-C among a community sample of 1,006 English-speaking children (aged 8–18 years). Exploratory factor analysis was conducted using a random subsample (n = 504) to assess the underlying factor structure. Items with poor factor loadings were removed. Confirmatory factor analysis, using the second subsample (n = 502), was used to cross-validate the factor structure revealed by exploratory factor analysis and compare it to the original 3-factor model and other model variants. Exploratory factor analysis revealed that the original PCS-C and a revised 3-factor model comprising 11 of the original 13 PCS-C items, all loading on their original factors, provided adequate fit to the data. The revised model provided statistically better fit to the data compared to all other model variants, suggesting that the English PCS-C may be better understood using a revised 11-item oblique 3-factor model. Perspective: This is the first examination of the factorial validity of the widely used English version of the PCS-C in a large community sample of English-speaking children. A revised 11-item, 3-factor model provided statistically better fit to the data compared to the original model and other model variants

Validation of the numerical rating scale for pain intensity and unpleasantness in pediatric acute postoperative pain: sensitivity to change over time

This study evaluates the construct validity (including sensitivity to change) of the numerical rating scale (NRS) for pain intensity (I) and unpleasantness (U) and participant pain scale preferences in children/adolescents with acute postoperative pain. Eighty-three children aged 8 to 18 years (mean = 13.8, SD = 2.4) completed 3 pain scales including NRS, Verbal Rating Scale (VRS), and faces scales (Faces Pain Scale-Revised [FPS-R] and Facial Affective Scale [FAS], respectively) for pain intensity (I) and unpleasantness (U) 48 to 72 hours after major surgery, and the NRS, VRS and Functional Disability Index (FDI) 2 weeks after surgery. As predicted, the NRSI correlated highly with the VRSI and FPS-R and the NRSU correlated highly with the VRSU and FAS 48 to 72 hours after surgery. The FDI correlated moderately with the NRS at both time points. Scores on the NRSI and NRSU at 48 to 72 hours were significantly higher than at 2 weeks after surgery. Children found the faces scales the easiest to use while the VRS was liked the least and was the hardest to use. The NRS has adequate evidence of construct validity including sensitivity for both pain intensity and unpleasantness. This study further supports the validity of the NRS as a tool to measure both intensity and unpleasantness of acute pain in children

Structure of Posttraumatic Stress Disorder Symptoms in Pain and Pain-Free Patients Scheduled for Major Surgery

Factor-analytic studies of the structure of posttraumatic stress disorder (PTSD) symptoms have yielded inconsistent results. One of the reasons for the inconsistency may be that PTSD is highly comorbid with other disorders; the observed factor structure might depend on the particular comorbid disorder. One such disorder is chronic pain. The goal of the present study was to investigate whether PTSD symptom structure differs between pain and pain-free patients scheduled to undergo major surgery. Four hundred and forty-seven patients who were approached 7 to 10 days prior to scheduled surgery completed the PTSD Checklist-Civilian (PCL-C) Version and the Current Pain and Pain History Questionnaire; the latter was used to divide patients into pain (N = 175) and pain-free (N = 272) groups. Results showed that in pain-free patients, PTSD symptoms were best expressed as 2 symptom clusters (re-experiencing/avoidance; emotional numbing/hyperarousal) accounting for 52.4% of the variance. In pain patients, PTSD symptoms were best expressed as a single symptom cluster accounting for 51.1% of the variance. These results suggest different interrelationships among PTSD symptoms in these 2 populations. Results reflect the need for (1) controlling for pain in studies looking at PTSD-symptom expression and (2) further research on PTSD-symptom expression in pain populations

Identification of pain-related psychological risk factors for the development and maintenance of pediatric chronic postsurgical pain

Background: The goals of this study were to examine the trajectory of pediatric chronic postsurgical pain (CPSP) over the first year after surgery and to identify acute postsurgical predictors of CPSP. Methods: Eighty-three children aged 8–18 years (mean 13.8, standard deviation 2.4) who underwent major orthopedic or general surgery completed pain and pain-related psychological measures at 48–72 hours, 2 weeks (pain anxiety and pain measures only), and 6 and 12 months after surgery. Results: Results showed that 1 year after surgery, 22% of children developed moderate to severe CPSP with minimal functional disability. Children who reported a Numeric Rating Scale pain-intensity score $ 3 out of 10 two weeks after discharge were more than three times as likely to develop moderate/severe CPSP at 6 months and more than twice as likely to develop moderate/severe CPSP at 12 months than those who reported a Numeric Rating Scale pain score , 3 (6-month relative risk 3.3, 95% confidence interval 1.2–9.0 and 12-month relative risk 2.5, 95% confidence interval 0.9–7.5). Pain unpleasantness predicted the transition from acute to moderate/severe CPSP, whereas anxiety sensitivity predicted the maintenance of moderate/severe CPSP from 6 to 12 months after surgery. Conclusions: This study highlights the prevalence of pediatric CPSP and the role played by psychological variables in its development/maintenance. Risk factors that are associated with the development of CPSP are different from those that maintain it.MGP is supported by a Canada Graduate Scholarship – Doctoral Award from the Canadian Institutes of Health Research (CIHR). MGP is a recipient of a Lillian-Wright Maternal-Child Health Scholarship from York University, a trainee member of Pain in Child Health and a CIHR Strategic Training Fellow in Pain: Molecules to Community. JS is supported by a Ministry of Health and Long-Term Care Career Scientist Award. JK is supported by a CIHR Canada Research Chair in Health Psychology at York University

Parental risk factors for the development of pediatric acute and chronic postsurgical pain: a longitudinal study

Background: The goal of this longitudinal study was to examine the associations among psychological factors and pain reports of children and their parents over the 12 month period after pediatric surgery. Materials and methods: Included in the study were 83 children aged 8–18 years undergoing major surgery. In each case, the child and one of their parents completed measures of pain intensity and unpleasantness, psychological function, and functional disability at 48–72 hours, 2 weeks (child only), 6 months, and 12 months after surgery. Results: The strength of the correlation coefficients between the psychological measures of the parent and their child increased significantly over time. There was a fair level of agreement between parent ratings of child acute and chronic pain (6 months after surgery) and the child’s actual ratings. Parent and child pain anxiety scores 48–72 hours after surgery interacted significantly to predict pain intensity, pain unpleasantness, and functional disability levels 2 weeks after discharge from hospital. Parent pain catastrophizing scores 48–72 hours after surgery predicted child pain intensity reports 12 months later. Conclusion: These results raise the possibility that as time from surgery increases, parents exert greater and greater influence over the pain response of their children, so that by 12 months postsurgery mark, parent pain catastrophizing (measured in the days after surgery) is the main risk factor for the development of postsurgical pain chronicity.MGP is supported by a Canada Graduate Scholarship – Doctoral Award from the Canadian Institutes of Health Research (CIHR). MGP is a trainee member of Pain in Child Health, a CIHR Strategic Training Fellow in Pain: Molecules to Community and a recipient of a Lillian-Wright Maternal-Child Health Scholarship from York University. JS is supported by a Ministry of Health and Long-term Care Career Scientist Award. JK is supported by a CIHR Canada Research Chair in Health Psychology at York University. Funds to conduct the study were provided by Dr Katz’s Canada Research Chair

Maternal family history of hypertension attenuates neonatal pain responsivity.

Reduced sensitivity to naturally occurring and laboratory pain stimuli has been observed in individuals with hypertension, high-normal blood pressure, and a family history of hypertension. The present study sought to extend these findings by examining the relationship between familial history of hypertension and pain responsivity in neonates. Eighty infants had intramuscular (IM) injections of vitamin K performed in the delivery room within 1 h of birth as per institutional practice. Video recordings of the injection procedure were used by trained observers to code infant pain responses using facial grimacing and cry duration. Prior to the birth of the child, the infants’ parents each completed a family blood pressure history survey and these responses were used to identify infants with and without a maternal and paternal family history of hypertension. As compared to infants without a maternal family history of hypertension, infants with a maternal family history of hypertension had significantly shorter crying times, F(1, 74) = 6.96, p = .01, η2 = .086, and marginally lower facial grimacing scores, F(1, 74) = 2.68, p = .10, η2 = .035, during vitamin K injection. The presence of attenuated responses to the IM injection in neonates with a maternal family history of hypertension provides important and novel evidence that reduced pain responding in individuals at risk for hypertension is not a learned response style, but rather may arise from prenatal or genetic influences