***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: OBJECTIVE The goals of this study were to examine agreement and estimate differences in sensitivity between pain assessment scales . DESIGN  Multiple simultaneous pain assessment s by patients in acute pain after oral surgery were used to compare a four-category verbal rating scale ( VRS-4 ) and an 11-point numeric rating scale ( NRS-11 ) with a 100-mm visual analog scale ( VAS ) . The sensitivity of the scales ( i.e. , their ability [ power ] to detect differences between treatments ) was compared in a simulation model by sampling from true pairs of observations using varying treatment differences of predetermined size . RESULTS There was considerable variability in VAS scores within each VRS-4 or NRS-11 category both between patients and for repeated measures from the same patient . Simulation experiments showed that the VAS was systematic ally more powerful than the VRS-4 in all simulations performed . The sensitivity of the VAS and NRS-11 was approximately equal . CONCLUSIONS In this acute pain model , the VRS-4 was less sensitive than the VAS . The simulation results demonstrated similar sensitivity of the NRS-11 and VAS when comparing acute postoperative pain intensity . The choice between the VAS and NRS-11 can thus be based on subjective preferences & 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 Introduction This open-label , phase 3b study evaluated the effectiveness and tolerability of oral tapentadol prolonged release ( PR ; 50–250 mg twice daily [ b.i.d . ] ) for managing severe , chronic low back pain in patients responding to World Health Organization ( WHO ) step III opioids but tolerating treatment poorly . Equianalgesic ratios for tapentadol to prior strong opioids were calculated . Methods Patients rotated directly from prior WHO step III opioids to tapentadol .  Patients received tapentadol PR ( 50–250 mg b.i.d . ) during 5-week titration and 7-week maintenance periods . Tapentadol immediate release ( IR ) 50 mg ( ≤twice/day , ≥4 h apart ) was allowed ( total daily dose of tapentadol PR and IR ≤500 mg/day ) . The primary endpoint was responder rate 1 at week 6 ( percentage of patients with the same or less pain intensity [ 11-point numerical rating scale ( NRS ; 3-day average ) ] vs week −1 ) . Results Responder rate 1 at week 6 ( last observation carried forward [ LOCF ] ) was 80.9 % ( 76/94 ; P < 0.0001 vs. the null responder hypothesis rate [ < 60 % ] ) , result ing in a positive trial despite premature termination ( 136 recruited of 180 planned ) . Significant improvements from baseline in pain intensity and neuropathic pain symptoms were observed at weeks 6 and 12 with tapentadol PR ( P < 0.05 ) . Equianalgesic ratios were calculated for PR formulations alone and for PR and IR formulations combined for tapentadol  to oxycodone , buprenorphine , fentanyl , morphine , and hydromorphone . The prevalences of adverse events reported as the reason for switching to tapentadol  ( most commonly constipation and nausea ) decreased over time . Conclusions Tapentadol PR ( 50–250 mg b.i.d . ) provided at least comparable pain relief and improved tolerability versus prior strong opioids in patients with severe , chronic low back pain responding to WHO step III therapy . Conversion from strong opioids to tapentadol PR , with its two mechanisms of action , went smoothly considering overall effectiveness and tolerability outcomes . Equianalgesic ratios of tapentadol to oxycodone and other strong opioids were in line with other phase 3/3b studies Objective : To evaluate the efficacy and safety of tapentadol extended release ( ER ) for the management of moderate to severe chronic low back pain . Research design : Patients ( N = 981 ) were r and omized 1:1:1 to receive tapentadol ER 100 – 250 mg b.i.d . , oxycodone HCl controlled release ( CR ) 20 – 50 mg b.i.d . , or placebo over 15 weeks ( 3-week titration period , 12-week maintenance period ) . Main outcome measures : Efficacy was assessed as change from baseline in average pain intensity ( 11-point NRS ) at week 12 of the maintenance period and throughout the maintenance period ; last observation carried forward was used to impute missing pain scores . Adverse events ( AEs ) were monitored throughout the study . Results : Tapentadol ER significantly reduced average pain intensity versus placebo at week 12 ( least squares mean difference vs placebo [ 95 % confidence interval ] , −0.8 [ −1.22 , −0.47 ] ; p < 0.001 ) and throughout the maintenance period ( −0.7 [ −1.06,−0.35 ] ; p < 0.001 ) . Oxycodone CR significantly reduced average pain intensity versus placebo at week 12 ( −0.9 [ −1.24,−0.49 ] ; p < 0.001 ) and throughout the maintenance period ( −0.8 [ −1.16,−0.46 ] ; p < 0.001 ) . Tapentadol ER was associated with a lower incidence of treatment-emergent AEs ( TEAEs ) than oxycodone CR . Gastrointestinal TEAEs , including constipation , nausea , and vomiting , were among the most commonly reported TEAEs ( placebo , 26.3 % ; tapentadol ER , 43.7 % ; oxycodone CR , 61.9 % ) . The odds of experiencing constipation or the composite of nausea and /or vomiting were significantly lower with tapentadol ER than with oxycodone CR ( both p < 0.001 ) . Conclusions : Tapentadol ER ( 100 – 250 mg b.i.d . ) effectively relieved moderate to severe chronic low back pain over 15 weeks and had better gastrointestinal tolerability than oxycodone HCl CR ( 20 – 50 mg b.i.d . ) OBJECTIVE To establish basic epidemiological data on  chronic pain ( duration > 3 months ) in a defined population . Relationships between age , gender , and social class were tested . DESIGN A survey of pain symptoms , including location , intensity , duration , and functional capacity , was conducted by means of a mail question naire . SETTING General population s in two Swedish primary health care districts . Medical care was provided in a state health system . SUBJECTS A r and om sample ( from the population register ) of 15 % of the population aged 25 - 74 ( n = 1,806 ) . The response rate was 90 % . OUTCOME MEASURES Descriptive epidemiologic data in relation to objectives of the study . RESULTS Without sex differences , 55 % ( 95 % confidence interval , 53 - 58 % ) of the population had perceived persistent pain for 3 months and 49 % for 6 months . Among individuals with chronic pain , 90 % localized their pain to the musculoskeletal system to a variable extent . Women experienced more multiple localizations of pain and had pain in the neck , shoulder , arm , and thigh to a greater extent than men . Prevalence of pain increased by age up to 50 - 59 years for both genders and then slowly decreased . The neck-shoulder area was the most common site of pain ( 30.2 % ) , followed by the lower back ( 23.2 % ) . Even in the youngest age groups more than one of four reported chronic pain . Blue-collar workers and employers ( including farmers ) reported chronic pain to a greater extent than other groups . In 13 % of the population , manifest pain problems were associated with reduced functional capacity . CONCLUSION Chronic pain symptoms are common but unevenly distributed in a general population . The results may influence planning and consultation in primary health care as well as warranting selective prevention activities BACKGROUND Tapentadol is a novel , central ly acting analgesic with 2 mechanisms of action : µ-opioid receptor agonism and norepinephrine reuptake inhibition . This r and omized , open-label phase 3 study ( Clinical Trials.gov Identifier : NCT00361504 ) assessed the long-term safety and tolerability of tapentadol extended release ( ER ) in patients with chronic knee or hip osteoarthritis pain or low back pain . METHODS Patients were r and omized 4:1 to receive controlled , adjustable , oral , twice-daily doses of tapentadol ER ( 100 to 250 mg ) or oxycodone HCl controlled release ( CR ; 20 to 50 mg ) for up to 1 year . Efficacy evaluations included assessment s at each study visit of average pain intensity ( 11-point numerical rating scale ) over the preceding 24 hours . Treatment-emergent adverse events ( TEAEs ) and discontinuations were monitored throughout the study . RESULTS A total of 1,117 patients received at least 1 dose of study drug . Mean ( st and ard error ) pain intensity scores in the tapentadol ER and oxycodone CR groups , respectively , were 7.6 ( 0.05 ) and 7.6 ( 0.11 ) at baseline and decreased to 4.4 ( 0.09 ) and 4.5 ( 0.17 ) at endpoint . The overall incidence of TEAEs was 85.7 % in the tapentadol ER group and 90.6 % in the oxycodone CR group . In the tapentadol ER and oxycodone CR groups , respectively , TEAEs led to discontinuation in 22.1 % and 36.8 % of patients ; gastrointestinal TEAEs led to discontinuation in 8.6 % and 21.5 % of patients . CONCLUSION Tapentadol ER ( 100 to 250 mg bid ) was associated with better gastrointestinal tolerability than oxycodone HCl CR ( 20 to 50 mg bid ) and provided sustainable relief of moderate to severe chronic knee or hip osteoarthritis or low back pain for up to 1 year OBJECTIVE To evaluate via retrospective analysis the efficacy and tolerability of tapentadol extended release ( ER ; 100 - 250 mg bid ) based on patient-specific factors , including baseline pain intensity , prior opioid experience , gender , and body mass index ( BMI ) . DESIGN Data were pooled from three r and omized , double-blind phase III studies of similar design that evaluated the efficacy and tolerability of tapentadol ER for the management of moderate to severe , chronic osteoarthritis knee pain ( NCT00421928 , NCT00486811 ) or low back pain ( NCT00449176 ) . SETTING In the original trials , patients were recruited at primary , secondary , and tertiary care centers , institutional setting s , and private practice s in North America , Europe , Australia , and New Zeal and . PATIENTS Data were analyzed separately for groups of patients divided by baseline pain intensity , prior opioid experience , gender , and BMI . INTERVENTIONS Patients received twice-daily placebo , tapentadol ER ( 100 - 250 mg ) , or oxycodone HCl controlled release ( CR ; 20 - 50 mg ) for a 3-week titration and 12-week maintenance period . MAIN OUTCOME MEASURES Changes from baseline in average pain intensity ( 11-point numerical rating scale ) at week 12 of the maintenance period and for the overall maintenance period . RESULTS Efficacy and tolerability were evaluated in 2,968 and 2,974 patients , respectively . The efficacy of tapentadol ER was shown in sub population s divided by baseline 
    Output:
    
Tapentadol extended release is associated with a reduction in pain intensity in comparison to placebo and oxycodone .
Tapentadol is associated with a more favourable safety profile and tolerability than oxycodone