***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 Laparoscopic adhesiolysis for chronic abdominal pain is controversial and is not evidence based . We aim ed to test our hypothesis that laparoscopic adhesiolysis leads to substantial pain relief and improvement in quality of life in patients with adhesions and chronic abdominal pain . METHODS Patients had diagnostic laparoscopy for chronic abdominal pain attributed to adhesions ; other causes for their pain had been excluded . If adhesions were confirmed during diagnostic laparoscopy , patients were r and omly assigned either to laparoscopic adhesiolysis or no treatment . Treatment allocation was concealed from patients , and assessors were unaware of patients ' treatment and outcome . Pain was assessed for 1 year by visual analogue score ( VAS ) score ( scale 0 - 100 ) , pain change score , use of analgesics , and quality of life score . Analysis was by intention to treat . FINDINGS Of 116 patients enrolled for diagnostic laparoscopy , 100 were r and omly allocated either laparoscopic adhesiolysis ( 52 ) or no treatment ( 48 ) . Both groups reported substantial pain relief and a significantly improved quality of life , but there was no difference between the groups ( mean change from baseline of VAS score at 12 months : difference 3 points , p=0.53 ; 95 % CI -7 to 13 ) . INTERPRETATION Although laparoscopic adhesiolysis relieves chronic abdominal pain , it is not more beneficial than diagnostic laparoscopy alone . Therefore , laparoscopic adhesiolysis can not be recommended as a treatment for adhesions in patients with chronic abdominal pain Background It is an inherent assumption in r and omised controlled trials that the drug effect can be estimated by subtracting the response during placebo from the response during active drug treatment . Objective To test the assumption of additivity . The primary hypothesis was that the total treatment effect is smaller than the sum of the drug effect and the placebo effect . The secondary hypothesis was that non-additivity was most pronounced in participants with large placebo effects . Methods We used a within-subject r and omised blinded balanced placebo design and included 48 healthy volunteers ( 50 % males ) , mean ( SD ) age 23.4 ( 6.2 ) years . Experimental pain was induced by injections of hypertonic saline into the masseter muscle . Participants received four injections with hypertonic saline along with lidocaine or matching placebo in r and omised order : A : received hypertonic saline/told hypertonic saline ; B : received hypertonic saline+lidocaine/told hypertonic saline ; C : received hypertonic saline+placebo/told hypertonic saline+pain killer ; D : received hypertonic saline+lidocaine/told hypertonic saline+pain killer . The primary outcome measure was the area under the curve ( AUC , mm2 ) of pain intensity during injections . Results There was a significant difference between the sum of the drug effect and the placebo effect ( mean AUC 6279 mm2 ( 95 % CI , 4936–7622 ) ) and the total treatment effect ( mean AUC 5455 mm2 ( 95 % CI , 4585–6324 ) ) ( P = 0.049 ) . This difference was larger for participants with large versus small placebo effects ( P = 0.015 ) , and the difference correlated significantly with the size of the placebo effect ( r = 0.65 , P = 0.006 ) . Conclusion Although this study examined placebo effects and not the whole placebo response as in r and omised controlled trials , it does suggest that the additivity assumption may be incorrect , and that the estimated drug effects in r and omised controlled trials may be underestimated , particularly in studies reporting large placebo responses . The implication s for r and omised controlled trials and systematic review s need to be discussed Background : Endoscopic treatment for gastro-oesophageal reflux disease ( GORD ) is rapidly emerging , but there is a great need for r and omised controlled trials to evaluate the efficacy . Design and setting : A single-centre , double-blind , r and omised , sham-controlled trial of endoscopic gastroplication by the Endocinch suturing system . Patients and interventions : 60 patients with GORD were r and omly assigned to three endoscopic gastroplications ( n = 20 ) , a sham procedure ( n = 20 ) or observation ( n = 20 ) . The research nurse and patients in the active and sham groups were blinded to the procedure assignment . After 3 months , open-label active treatment was offered to all patients . Outcome measures : The primary outcome measures were proton pump inhibitor ( PPI ) use and GORD symptoms , and secondary measures were quality of life , 24-h oesophageal acid exposure , oesophageal manometry and adverse events . Follow-up assessment s were performed at 3 , 6 and 12 months . Results : At 3 months , the percentage of patients who had reduced drug use by ⩾50 % was greater in the active treatment group ( 65 % ) than in the sham ( 25 % ) or observation groups ( 0 % ) ( p<0.02 ) . Symptoms ( heartburn and to a lesser extent regurgitation ) improved more in the active group than in the sham group . Three Short Form-20 quality of life subscales ( role function , general health and bodily pain perception ) improved in the active group versus sham . Oesophageal acid exposure was modestly decreased after active treatment ( p<0.02 ) , but not significantly greater than after the sham procedure ( p = 0.61 ) . The active treatment effects on PPI use , symptoms and quality of life persisted after 6 and 12 months of open-label follow-up ( n = 41 ) , but 29 % of patients were retreated in this period . No serious adverse events occurred . Conclusions : Endoscopic gastroplication , using the Endocinch device , reduced acid-inhibitory drug use , improved GORD symptoms and improved the quality of life at 3 months compared with a sham procedure . The effects persisted up to 12 months . However , the reduction in oesophageal acid exposure was not greater after endoscopic treatment than after a sham procedure Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more & NA ; The objective was to investigate the relationship between pain relief scores produced by placebo and by active interventions in r and omised controlled trials ( RCTs ) . Individual patient categorical pain relief scores from 5 placebo‐controlled single‐dose parallel‐group RCTs in acute postoperative pain were used to calculate the percentage of the maximum possible pain relief score ( % maxTOTPAR ) for the different treatments . One hundred and thirty of the 525 patients in the 5 trials had a placebo .  Individual patients ' scores with placebo varied from 0 to 100 % of the maximum possible pain relief . The proportion who obtained more than 50 % of the maximum possible pain relief with placebo varied from 7 % to 37 % across the trials ; with the active drugs the variation was from 5 to 63 % . Mean placebo scores were related to the mean score for the active treatments in each study ; the higher the mean active score , the higher the mean placebo score . This relationship disappeared when median values were used . Medical folklore has it that the amount of relief obtained with placebo is one‐third of the maximum possible ( and does not vary ) , and that one‐third of patients respond to placebo . The results show that the amount of relief obtained with placebo varies considerably between patients , that 38 % of patients obtained more than 10 % of the maximum possible relief , and 16 % obtained greater than 50 % . In double‐blind , r and omised parallel‐group studies of high quality placebo scores should not vary . Despite these conditions being met the placebo scores did vary . The previous explanation , of a relationship between the mean placebo scores and the mean scores for the active treatments was not supported BACKGROUND Vertebroplasty has become a common treatment for painful osteoporotic vertebral fractures , but there is limited evidence to support its use . METHODS We performed a multicenter , r and omized , double-blind , placebo-controlled trial in which participants with one or two painful osteoporotic vertebral fractures that were of less than 12 months ' duration and unhealed , as confirmed by magnetic resonance imaging , were r and omly assigned to undergo vertebroplasty or a sham procedure . Participants were stratified according to treatment center , sex , and duration of symptoms ( < 6 weeks or > or = 6 weeks ) . Outcomes were assessed at 1 week and at 1 , 3 , and 6 months . The primary outcome was overall pain ( on a scale of 0 to 10 , with 10 being the maximum imaginable pain ) at 3 months . RESULTS A total of 78 participants were enrolled , and 71 ( 35 of 38 in the vertebroplasty group and 36 of 40 in the placebo group ) completed the 6-month follow-up ( 91 % ) . Vertebroplasty did not result in a significant advantage in any measured outcome at any time point . There were significant reductions in overall pain in both study groups at each follow-up assessment . At 3 months , the mean ( + /-SD ) reductions in the score for pain in the vertebroplasty and control groups were 2.6+/-2.9 and 1.9+/-3.3 , respectively ( adjusted between-group difference , 0.6 ; 95 % confidence interval , -0.7 to 1.8 ) . Similar improvements were seen in both groups with respect to pain at night and at rest , physical functioning , quality of life , and perceived improvement . Seven incident vertebral fractures ( three in the vertebroplasty group and four in the placebo group ) occurred during the 6-month follow-up period . CONCLUSIONS We found no beneficial effect of vertebroplasty as compared with a sham procedure in patients with painful osteoporotic vertebral fractures , at 1 week or at 1 , 3 , or 6 months after treatment . ( Australian New Zeal and Clinical Trials Registry number , ACTRN012605000079640 . Abstract Objective To investigate whether a sham device ( a vali date d sham acupuncture needle ) has a greater placebo effect than an inert pill in patients with persistent arm pain . Design A single blind r and omised controlled trial created from the two week placebo run-in periods for two nested trials that compared acupuncture and amitriptyline with their respective placebo controls . Comparison of participants who remained on placebo continued beyond the run-in period to the end of the study . Setting Academic medical centre . Participants 270 adults with arm pain due to repetitive use that had lasted at least three months despite treatment and who scored ≥3 on a 10 point pain scale . Interventions Acupuncture with sham device twice a week for six weeks or placebo pill once a day for eight weeks . Main outcome measures Arm pain measured on a 10 point pain scale . Secondary outcomes were symptoms measured by the Levine symptom severity scale , function measured by Pransky 's upper extremity function scale , and grip strength . Results Pain decreased during the two week placebo run-in period in both the sham device and placebo pill groups , but changes were not different between the groups ( −0.14 , 95 % confidence interval −0.52 to 0.25 , P = 0.49 ) . Changes in severity scores for arm symptoms and grip strength were similar between groups , but arm function improved more in the placebo pill group ( 2.0 , 0.06 to 3.92 , P = 0.04 ) . Longitudinal regression analyses that followed participants throughout the treatment period showed significantly greater downward slopes per week on the 10 point arm pain scale in the sham device group than in the placebo pill group ( −0.33 ( −0.40 to −0.26 ) v −0.15 ( −0.21 to −0.09 ) , P = 0.0001 ) and on the symptom severity scale ( −0.07 ( −0.09 to −0.05 ) v −0.05 ( −0.06 to −0.03 ) , P = 0.02 ) . Differences were not significant , however , on the function scale or for grip strength . Reported adverse effects were different in the two groups . Conclusions The sham device had greater effects than the placebo pill on self reported pain and severity of symptoms over the entire course of treatment but not during the two week placebo run in . Placebo effects seem to be malleable and depend on the behaviours embedded in medical rituals BACKGROUND Vertebroplasty is commonly used to treat painful , osteoporotic vertebral compression fractures . METHODS In this multicenter trial , we r and omly assigned 131 patients who had one to three painful osteoporotic vertebral compression fractures to undergo either vertebroplasty or a simulated procedure without cement ( control group ) . The primary outcomes were scores on the modified Rol and -Morris Disability Question naire ( RDQ ) ( on a scale of 0 to 23 , with higher scores indicating greater disability ) and patients ' ratings of average pain intensity during the preceding 24 hours at 1 month ( on a scale of 0 to 10 , with higher scores indicating more severe pain ) . Patients were allowed to cross over to the other study group after 1 month . RESULTS All patients underwent the assigned intervention ( 68 vertebroplasties and 63 simulated procedures ) . The baseline characteristics were similar in the two groups . At 1 month , there was no significant difference between the vertebroplasty group and the control group in either the RDQ score ( difference , 0.7 ; 95 % confidence interval [ CI ] , -1.3 to 2.8 
    Output:
    
Meta-regression analysis showed that duration of follow-up did not have a significant effect on the magnitude of the placebo response and that the strongest predictor of placebo response was subjectivity of the outcome .
Conclusions This is the first study to investigate the temporal changes of placebo response in surgical trials and the first to investigate the sources of heterogeneity of placebo response .
Placebo response in surgical trials was large for subjective outcomes , persisting as a time-invariant effect throughout blinded follow-up .
Therefore , placebo response can not be minimized in these types of outcomes through their appraisal at alternative time points .
The analyses suggest that objective outcomes may be preferable as trial end-points .