human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Pain is the primary indication for both primary and revision total knee arthroplasty ( TKA ) ; however , most arthroplasty outcome measures do not take pain into account . OBJECTIVE To document the prospect i ve pain experience following TKA , with subjective pain-specific question naires to determine if comorbidities , preoperative pain or preoperative pain catastrophizing scores are predictive of long-term pain outcomes . METHODS Fifty-five patients with a primary diagnosis of osteoarthritis of the knee , who were scheduled to undergo TKA , were asked to fill out the McGill Pain Question naire ( MPQ ) and the Pain Catastrophizing Scale ( PCS ) preoperatively and at three , 12 and 24 months follow-up . Comorbidities were extracted from the Queen Elizabeth II Health Sciences Centre health information system . RESULTS The overall response rate ( return of completed question naires ) was 84 % . There was a significant decrease in the MPQ scores ( P<0.05 ) postoperatively . PCS scores did not change over time . Receiver operating characteristic curves revealed the number of comorbidities per patient predicted the presence of pain postoperatively , as documented by the numerical rating subscale of the MPQ at 24 months ( P<0.05 ) . Receiver operating characteristic curves for preoperative PCS and rumination subscale scores predicted the presence of pain , as measured by the Pain Rating Index subscale of the MPQ at 24 months ( P<0.05 ) . Preoperative PCS scores and comorbidities were significantly higher in the persistent pain group ( P<0.05 ) . CONCLUSIONS The number of comorbidities predicted the presence of pain at 24 months follow-up and , for the first time , preoperative PCS scores were shown to predict chronic postoperative pain . This may enable the identification of knee arthroplasty patients at risk for persistent postoperative pain , thus allowing for efficient administration of preoperative interventions to improve arthroplasty outcomes BACKGROUND The relief of pain and the restoration of functional activities are the main outcomes of primary total knee arthroplasty for the treatment of osteoarthritis . This paper examines the preoperative predictors of pain and functional outcome at one and two years following total knee arthroplasty . METHODS Patients were recruited for a prospect i ve observational study of primary total knee arthroplasty for the treatment of osteoarthritis from centers in the United States , the United Kingdom , and Australia . Research assistants recruited the patients and collected the clinical history and physical examination data preoperatively and at three , twelve , and twenty-four months postoperatively . The Western Ontario and McMaster University Osteoarthritis Index ( WOMAC ) , Short Form-36 ( SF-36 ) , and demographic data were obtained by self-administered patient question naires . RESULTS We recruited 860 patients and obtained one-year WOMAC data on 759 patients ( 88 % ) and two-year data on 701 ( 82 % ) . The mean age was seventy years , and 59 % of the patients were female . Using hierarchical regression models , we found that the most significant preoperative predictors of worse scores on the pain and function domains of the WOMAC scale and on the physical functioning domain of the SF-36 at one and two years postoperatively were low preoperative scores , a higher number of comorbid conditions , and a low SF-36 mental health score . After adjusting for these predictors , we found that the functional status of the patients from the United Kingdom was significantly worse than that of the patients from the other countries and the difference was clinical ly important at both the one-year and two-year follow-up examination ( p < 0.0005 ) . The mean WOMAC pain scores for the three countries were not significantly different at one year , and , although they were significantly different at two years ( p = 0.025 ) , the difference was not clinical ly important . CONCLUSIONS Patients who have marked functional limitation , severe pain , low mental health score , and other comorbid conditions before total knee arthroplasty are more likely to have a worse outcome at one year and two years postoperatively . After adjusting for these predictors , it was found that patients from the United Kingdom had significantly worse functional outcomes but similar pain relief compared with those from the United States and Australia & NA ;  Pain intensity is frequently measured on an 11‐point pain intensity numerical rating scale ( PI‐NRS ) , where 0=no pain and 10=worst possible pain . However , it is difficult to interpret the clinical importance of changes from baseline on this scale ( such as a 1‐ or 2‐point change ) . To date , there are no data driven estimates for clinical ly important differences in pain intensity scales used for chronic pain studies . We have estimated a clinical ly important difference on this scale by relating it to global assessment s of change in multiple studies of chronic pain . Data on 2724 subjects from 10 recently completed placebo‐controlled clinical trials of pregabalin in diabetic neuropathy , postherpetic neuralgia , chronic low back pain , fibromyalgia , and osteoarthritis were used . The studies had similar design s and measurement instruments , including the PI‐NRS , collected in a daily diary , and the st and ard seven‐point patient global impression of change ( PGIC ) , collected at the endpoint . The changes in the PI‐NRS from baseline to the endpoint were compared to the PGIC for each subject . Categories of ‘ much improved ’ and ‘ very much improved ’ were used as determinants of a clinical ly important difference and the relationship to the PI‐NRS was explored using graphs , box plots , and sensitivity/specificity analyses . A consistent relationship between the change in PI‐NRS and the PGIC was demonstrated regardless of study , disease type , age , sex , study result , or treatment group . On average , a reduction of approximately two points or a reduction of approximately 30 % in the PI‐NRS represented a clinical ly important difference . The relationship between percent change and the PGIC was also consistent regardless of baseline pain , while higher baseline scores required larger raw changes to represent a clinical ly important difference . The application of these results to future studies may provide a st and ard definition of clinical ly important improvement in clinical trials of chronic pain therapies . Use of a st and ard outcome across chronic pain studies would greatly enhance the comparability , validity , and clinical applicability of these studies To describe the natural history of pain after total knee arthroplasty and to identify factors predicting excessive postoperative pain , we used a prospect i ve , observational study assessing clinical and radiographic variables preoperatively and at 1 , 3 , 6 , and 12 months after knee replacement .  Data sources included the visual analog pain scale and other measures of patient health , psychologic state , and component reliability . Regression analyses were conducted to identify specific factors predictive of postoperative pain , controlling for ine quality of variables , and confirmed using regression diagnostics . For 116 patients ( 149 knees ; mean age , 66 years ; 55.2 % women ) , significant pain was reported by 72.3 % , 44.4 % , 22.6 % , 18.4 % , and 13.1 % , respectively . No intergroup differences existed for anesthesia , weight , age , or gender . Patients with greater preoperative pain had more postoperative pain , used more home therapy , and postoperative manipulations . Preoperative depression and anxiety were associated with heightened pain at 1 year . Pain after knee replacement resolves quickly , declining to approximately 1/2 by 3 months . However , one in eight patients report moderate to severe pain 1 year after surgery despite an absence of clinical or radiographic abnormalities . Development of office-based preoperative screening tools and interventions for these patients may reduce postoperative costs and improve patient-perceived outcomes Through empirical methods we now characterize patients with chronic pain as either dysfunctional , interpersonally distressed , or adaptive copers . Study ing factors that differentiate these groups may reveal the behavioral processes that determine adjustment to pain . Subjects for this study were 190 patients referred for treatment of chronic pain . They were classified as dysfunctional ( n = 41 ) , interpersonally distressed ( n = 28 ) or adaptive copers ( n = 59 ) based on the Multidimensional Pain Inventory ( Kerns , R.D. , Turk , D.C. and Rudy , T.E. , The West Haven-Yale Multidimensional Pain Inventory ( WHYMPI ) , Pain , 23 ( 1985 ) 345 - 356 ) and compared on measures of  pain-related anxiety and pain acceptance .  Our analyses showed that the dysfunctional group reported greater pain-related anxiety and less acceptance of pain than the other groups . Additional analyses , statistically controlling for pain severity and depression , showed that the patient subtypes continued to differ on pain-related anxiety and acceptance . Discriminant function analyses including pain-related anxiety and acceptance correctly classified 72.5 % of dysfunctional and 90.9 % of adaptive copers . Again , anxiety and acceptance contributed uniquely to classification independent of depression and pain intensity . Pain-related anxiety and acceptance of pain appear to be unique behavioral dimensions of adjustment to chronic pain . Decreasing anxiety and increasing acceptance may ' move ' patients with chronic pain from the dysfunctional to the adaptive coper category Objectives : This study was a prospect i ve investigation of the extent to which psychologic variables could be predictive of postoperative pain . Study aims were : 1 ) to evaluate whether an assessment of pre-operative distress factors could predict the intensity of postoperative pain ; and 2 ) to characterize the unique pattern in which anxiety and pain catastrophizing scores relate to postoperative pain . Methods : The Pain Catastrophizing Scale and the State-Trait Anxiety Inventory were administered to 38 patients scheduled for elective abdominal surgery .  The question naires were completed on the day of admission , a day before the operation . On day 1 and day 2 following the operation , perception of pain intensity at the surgical wound was assessed by visual analog scale . Results : The Pain Catastrophizing Scale and State-Trait Anxiety Inventory scores were significantly correlated with the postoperative pain scores . A linear regression analysis showed that Pain Catastrophizing Scale predicted the level of postoperative pain intensity even after controlling for state anxiety and that trait anxiety was not a significant predictor . In addition , analysis of the unique pattern of each predictor related to postoperative pain intensity indicated a linear curve for the Pain Catastrophizing Scale and curvilinear curve for the state anxiety . Discussion : The results are discussed in light of appraisal and coping theories . It is suggested that a simple assessment of preoperative catastrophizing tendency and anxiety scores may assist medical teams in postoperative pain management UNLABELLED The aim of this study was to examine whether treatments based on different theories change pain catastrophizing and internal control of pain , and whether changes in these factors mediate treatment outcome . Participants were 211 patients with nonspecific chronic low back pain ( CLBP ) participating in a r and omized controlled trial , attending active physical treatment ( APT , n = 52 )  , cognitive-behavioral treatment ( CBT , n = 55 ) , treatment combining the APT and CBT ( CT , n = 55 ) , or waiting list ( WL , n = 49 ) . Pain catastrophizing decreased in all 3 active treatment groups and not in the WL . There was no difference in the change in internal control across all 4 groups . In all the active treatment groups , patients improved regarding perceived disability , main complaints , and current pain at post-treatment , and no changes were observed in the WL group . Depression only changed significantly in the APT group . Change in pain catastrophizing mediated the reduction of disability , main complaints , and pain intensity . In the APT condition , pain catastrophizing also mediated the reduction of depression . Not only cognitive-behavioral treatments but also a physical treatment produced changes in pain catastrophizing that seemed to mediate the outcome of the treatment significantly . The implication s and limitations of these results are discussed . PERSPECTIVE This article shows that treatment elements that do not deliberately target cognitive factors can reduce pain catastrophizing . Reduction in pain catastrophizing seemed to mediate the improvement of functioning in patients with chronic low back pain . The results might contribute to the development of more effective interventions Within the context of a double blind r and omized controlled parallel trial of 2 nonsteroidal antiinflammatory drugs , we vali date d WOMAC , a new multidimensional , self-administered health status instrument for patients with osteoarthritis of the hip or knee . The pain , stiffness and physical function subscales fulfil conventional criteria for face , content and construct validity , reliability , responsiveness and relative efficiency . WOMAC is a disease-specific purpose built high performance instrument for evaluative research in osteoarthritis clinical trials & NA ; The purpose of this study was to determine the levels of change on st and ard pain scales that represent clinical ly important differences to patients . Data from analgesic studies are often difficult to interpret because the clinical importance of the results is not obvious . Differences between groups , as summarized by a change in mean values over time , can be difficult to apply to clinical care . Baseline scores vary widely and group mean differences could reflect large changes in a few patients , small changes in many patients , or any combination of these outcomes . Determination of the proportion of patients who have a clinical ly important improvement in their pain would provide a more interpretable result with direct clinical implication s. However , determining a clinical ly important outcome requires information about the degree of change over time that is clinical ly important . Data from the titration phase of a multiple cross‐over r and omized clinical trial of oral transmucosal fentanyl citrate ( OTFC )  for the treatment of cancer‐related breakthrough pain were re‐analyzed to examine the differences in pain scores between treatment episodes that did and did not yield adequate pain relief . The scales evaluated were absolute pain intensity difference ( PID , 0–10 scale ) , percentage pain intensity difference ( PID% , 0–1 
    Output:
    
agent
This study provides moderate-level evidence for pain catastrophizing as an independent predictor of chronic pain post-TKA .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Pain is the primary indication for both primary and revision total knee arthroplasty ( TKA ) ; however , most arthroplasty outcome measures do not take pain into account . OBJECTIVE To document the prospect i ve pain experience following TKA , with subjective pain-specific question naires to determine if comorbidities , preoperative pain or preoperative pain catastrophizing scores are predictive of long-term pain outcomes . METHODS Fifty-five patients with a primary diagnosis of osteoarthritis of the knee , who were scheduled to undergo TKA , were asked to fill out the McGill Pain Question naire ( MPQ ) and the Pain Catastrophizing Scale ( PCS ) preoperatively and at three , 12 and 24 months follow-up . Comorbidities were extracted from the Queen Elizabeth II Health Sciences Centre health information system . RESULTS The overall response rate ( return of completed question naires ) was 84 % . There was a significant decrease in the MPQ scores ( P<0.05 ) postoperatively . PCS scores did not change over time . Receiver operating characteristic curves revealed the number of comorbidities per patient predicted the presence of pain postoperatively , as documented by the numerical rating subscale of the MPQ at 24 months ( P<0.05 ) . Receiver operating characteristic curves for preoperative PCS and rumination subscale scores predicted the presence of pain , as measured by the Pain Rating Index subscale of the MPQ at 24 months ( P<0.05 ) . Preoperative PCS scores and comorbidities were significantly higher in the persistent pain group ( P<0.05 ) . CONCLUSIONS The number of comorbidities predicted the presence of pain at 24 months follow-up and , for the first time , preoperative PCS scores were shown to predict chronic postoperative pain . This may enable the identification of knee arthroplasty patients at risk for persistent postoperative pain , thus allowing for efficient administration of preoperative interventions to improve arthroplasty outcomes BACKGROUND The relief of pain and the restoration of functional activities are the main outcomes of primary total knee arthroplasty for the treatment of osteoarthritis . This paper examines the preoperative predictors of pain and functional outcome at one and two years following total knee arthroplasty . METHODS Patients were recruited for a prospect i ve observational study of primary total knee arthroplasty for the treatment of osteoarthritis from centers in the United States , the United Kingdom , and Australia . Research assistants recruited the patients and collected the clinical history and physical examination data preoperatively and at three , twelve , and twenty-four months postoperatively . The Western Ontario and McMaster University Osteoarthritis Index ( WOMAC ) , Short Form-36 ( SF-36 ) , and demographic data were obtained by self-administered patient question naires . RESULTS We recruited 860 patients and obtained one-year WOMAC data on 759 patients ( 88 % ) and two-year data on 701 ( 82 % ) . The mean age was seventy years , and 59 % of the patients were female . Using hierarchical regression models , we found that the most significant preoperative predictors of worse scores on the pain and function domains of the WOMAC scale and on the physical functioning domain of the SF-36 at one and two years postoperatively were low preoperative scores , a higher number of comorbid conditions , and a low SF-36 mental health score . After adjusting for these predictors , we found that the functional status of the patients from the United Kingdom was significantly worse than that of the patients from the other countries and the difference was clinical ly important at both the one-year and two-year follow-up examination ( p < 0.0005 ) . The mean WOMAC pain scores for the three countries were not significantly different at one year , and , although they were significantly different at two years ( p = 0.025 ) , the difference was not clinical ly important . CONCLUSIONS Patients who have marked functional limitation , severe pain , low mental health score , and other comorbid conditions before total knee arthroplasty are more likely to have a worse outcome at one year and two years postoperatively . After adjusting for these predictors , it was found that patients from the United Kingdom had significantly worse functional outcomes but similar pain relief compared with those from the United States and Australia & NA ;  Pain intensity is frequently measured on an 11‐point pain intensity numerical rating scale ( PI‐NRS ) , where 0=no pain and 10=worst possible pain . However , it is difficult to interpret the clinical importance of changes from baseline on this scale ( such as a 1‐ or 2‐point change ) . To date , there are no data driven estimates for clinical ly important differences in pain intensity scales used for chronic pain studies . We have estimated a clinical ly important difference on this scale by relating it to global assessment s of change in multiple studies of chronic pain . Data on 2724 subjects from 10 recently completed placebo‐controlled clinical trials of pregabalin in diabetic neuropathy , postherpetic neuralgia , chronic low back pain , fibromyalgia , and osteoarthritis were used . The studies had similar design s and measurement instruments , including the PI‐NRS , collected in a daily diary , and the st and ard seven‐point patient global impression of change ( PGIC ) , collected at the endpoint . The changes in the PI‐NRS from baseline to the endpoint were compared to the PGIC for each subject . Categories of ‘ much improved ’ and ‘ very much improved ’ were used as determinants of a clinical ly important difference and the relationship to the PI‐NRS was explored using graphs , box plots , and sensitivity/specificity analyses . A consistent relationship between the change in PI‐NRS and the PGIC was demonstrated regardless of study , disease type , age , sex , study result , or treatment group . On average , a reduction of approximately two points or a reduction of approximately 30 % in the PI‐NRS represented a clinical ly important difference . The relationship between percent change and the PGIC was also consistent regardless of baseline pain , while higher baseline scores required larger raw changes to represent a clinical ly important difference . The application of these results to future studies may provide a st and ard definition of clinical ly important improvement in clinical trials of chronic pain therapies . Use of a st and ard outcome across chronic pain studies would greatly enhance the comparability , validity , and clinical applicability of these studies To describe the natural history of pain after total knee arthroplasty and to identify factors predicting excessive postoperative pain , we used a prospect i ve , observational study assessing clinical and radiographic variables preoperatively and at 1 , 3 , 6 , and 12 months after knee replacement .  Data sources included the visual analog pain scale and other measures of patient health , psychologic state , and component reliability . Regression analyses were conducted to identify specific factors predictive of postoperative pain , controlling for ine quality of variables , and confirmed using regression diagnostics . For 116 patients ( 149 knees ; mean age , 66 years ; 55.2 % women ) , significant pain was reported by 72.3 % , 44.4 % , 22.6 % , 18.4 % , and 13.1 % , respectively . No intergroup differences existed for anesthesia , weight , age , or gender . Patients with greater preoperative pain had more postoperative pain , used more home therapy , and postoperative manipulations . Preoperative depression and anxiety were associated with heightened pain at 1 year . Pain after knee replacement resolves quickly , declining to approximately 1/2 by 3 months . However , one in eight patients report moderate to severe pain 1 year after surgery despite an absence of clinical or radiographic abnormalities . Development of office-based preoperative screening tools and interventions for these patients may reduce postoperative costs and improve patient-perceived outcomes Through empirical methods we now characterize patients with chronic pain as either dysfunctional , interpersonally distressed , or adaptive copers . Study ing factors that differentiate these groups may reveal the behavioral processes that determine adjustment to pain . Subjects for this study were 190 patients referred for treatment of chronic pain . They were classified as dysfunctional ( n = 41 ) , interpersonally distressed ( n = 28 ) or adaptive copers ( n = 59 ) based on the Multidimensional Pain Inventory ( Kerns , R.D. , Turk , D.C. and Rudy , T.E. , The West Haven-Yale Multidimensional Pain Inventory ( WHYMPI ) , Pain , 23 ( 1985 ) 345 - 356 ) and compared on measures of  pain-related anxiety and pain acceptance .  Our analyses showed that the dysfunctional group reported greater pain-related anxiety and less acceptance of pain than the other groups . Additional analyses , statistically controlling for pain severity and depression , showed that the patient subtypes continued to differ on pain-related anxiety and acceptance . Discriminant function analyses including pain-related anxiety and acceptance correctly classified 72.5 % of dysfunctional and 90.9 % of adaptive copers . Again , anxiety and acceptance contributed uniquely to classification independent of depression and pain intensity . Pain-related anxiety and acceptance of pain appear to be unique behavioral dimensions of adjustment to chronic pain . Decreasing anxiety and increasing acceptance may ' move ' patients with chronic pain from the dysfunctional to the adaptive coper category Objectives : This study was a prospect i ve investigation of the extent to which psychologic variables could be predictive of postoperative pain . Study aims were : 1 ) to evaluate whether an assessment of pre-operative distress factors could predict the intensity of postoperative pain ; and 2 ) to characterize the unique pattern in which anxiety and pain catastrophizing scores relate to postoperative pain . Methods : The Pain Catastrophizing Scale and the State-Trait Anxiety Inventory were administered to 38 patients scheduled for elective abdominal surgery .  The question naires were completed on the day of admission , a day before the operation . On day 1 and day 2 following the operation , perception of pain intensity at the surgical wound was assessed by visual analog scale . Results : The Pain Catastrophizing Scale and State-Trait Anxiety Inventory scores were significantly correlated with the postoperative pain scores . A linear regression analysis showed that Pain Catastrophizing Scale predicted the level of postoperative pain intensity even after controlling for state anxiety and that trait anxiety was not a significant predictor . In addition , analysis of the unique pattern of each predictor related to postoperative pain intensity indicated a linear curve for the Pain Catastrophizing Scale and curvilinear curve for the state anxiety . Discussion : The results are discussed in light of appraisal and coping theories . It is suggested that a simple assessment of preoperative catastrophizing tendency and anxiety scores may assist medical teams in postoperative pain management UNLABELLED The aim of this study was to examine whether treatments based on different theories change pain catastrophizing and internal control of pain , and whether changes in these factors mediate treatment outcome . Participants were 211 patients with nonspecific chronic low back pain ( CLBP ) participating in a r and omized controlled trial , attending active physical treatment ( APT , n = 52 )  , cognitive-behavioral treatment ( CBT , n = 55 ) , treatment combining the APT and CBT ( CT , n = 55 ) , or waiting list ( WL , n = 49 ) . Pain catastrophizing decreased in all 3 active treatment groups and not in the WL . There was no difference in the change in internal control across all 4 groups . In all the active treatment groups , patients improved regarding perceived disability , main complaints , and current pain at post-treatment , and no changes were observed in the WL group . Depression only changed significantly in the APT group . Change in pain catastrophizing mediated the reduction of disability , main complaints , and pain intensity . In the APT condition , pain catastrophizing also mediated the reduction of depression . Not only cognitive-behavioral treatments but also a physical treatment produced changes in pain catastrophizing that seemed to mediate the outcome of the treatment significantly . The implication s and limitations of these results are discussed . PERSPECTIVE This article shows that treatment elements that do not deliberately target cognitive factors can reduce pain catastrophizing . Reduction in pain catastrophizing seemed to mediate the improvement of functioning in patients with chronic low back pain . The results might contribute to the development of more effective interventions Within the context of a double blind r and omized controlled parallel trial of 2 nonsteroidal antiinflammatory drugs , we vali date d WOMAC , a new multidimensional , self-administered health status instrument for patients with osteoarthritis of the hip or knee . The pain , stiffness and physical function subscales fulfil conventional criteria for face , content and construct validity , reliability , responsiveness and relative efficiency . WOMAC is a disease-specific purpose built high performance instrument for evaluative research in osteoarthritis clinical trials & NA ; The purpose of this study was to determine the levels of change on st and ard pain scales that represent clinical ly important differences to patients . Data from analgesic studies are often difficult to interpret because the clinical importance of the results is not obvious . Differences between groups , as summarized by a change in mean values over time , can be difficult to apply to clinical care . Baseline scores vary widely and group mean differences could reflect large changes in a few patients , small changes in many patients , or any combination of these outcomes . Determination of the proportion of patients who have a clinical ly important improvement in their pain would provide a more interpretable result with direct clinical implication s. However , determining a clinical ly important outcome requires information about the degree of change over time that is clinical ly important . Data from the titration phase of a multiple cross‐over r and omized clinical trial of oral transmucosal fentanyl citrate ( OTFC )  for the treatment of cancer‐related breakthrough pain were re‐analyzed to examine the differences in pain scores between treatment episodes that did and did not yield adequate pain relief . The scales evaluated were absolute pain intensity difference ( PID , 0–10 scale ) , percentage pain intensity difference ( PID% , 0–1 
    Output:
    