***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: Therapeutic trials often attempt to “ blind ” patient and investigator to the true nature of treatments received , reducing the influences of conscious or subconscious prejudices . In drug trials , this is accomplished with placebo tablets , but blinding in trials of physical treatments is more problematic . This issue arose in a clinical trial of transcutaneous electrical nerve stimulation ( TENS ) for patients with chronic low back pain . Several study design features were incorporated to promote blinding : use of sham TENS units visually identical with real units , exclusion of potential subjects with previous TENS experience , avoidance of a crossover design and use of identical visit frequency , instructions and modifications in electrode placement . Subjects were asked not to discuss treatments with the clinicians who performed outcome assessment s. Both patients and clinicians were asked to guess actual treatment assignments at the trial 's end . Every patient in the true TENS group believed the unit was functioning properly , but the degree of certainty varied . In the sham TENS group , 84 % also believed they had functioning units , but their certainty was significantly less than in the active treatment group . Differences in patient perceptions did not affect compliance , as the two groups had similar dropout rates , appointment compliance , days of TENS use and daily duration of TENS use . Clinicians guessed treatments correctly 61 % of the time ( as opposed to 50 % expected by chance ) , again suggesting partial success in blinding . These efforts at blinding may partly explain the negative trial results for TENS efficacy . We conclude that complete blinding is difficult to achieve because of sensory difference in treatment and unintended communication between patient and examiner . Nonetheless , trials of physical treatments can achieve partial blinding with the techniques described here , and the success of blinding can be assessed with simple questions at study completion Abstract  Variability  in patients ' response to interventions in pain and other clinical setting s is large . Many explanations such as trial methods , environment or culture have been proposed , but this paper sets out to show that the main cause of the variability may be r and om chance , and that if trials are small their estimate of magnitude of effect may be incorrect , simply because of the r and om play of chance . This is highly relevant to the questions of ‘ How large do trials have to be for statistical accuracy ? ’ and ‘ How large do trials have to be for their results to be clinical ly valid ? ’ The true underlying control event rate ( CER ) and experimental event rate ( EER ) were determined from single‐dose acute pain analgesic trials in over 5000 patients . Trial group size required to obtain statistically significant and clinical ly relevant ( 0.95 probability of number‐needed‐to‐treat within ±0.5 of its true value ) results were computed using these values . Ten thous and trials using these CER and EER values were simulated using varying group sizes to investigate the variation due to r and om chance alone . Most common analgesics have EERs in the range 0.4–0.6 and CER of about 0.19 . With such efficacy , to have a 90 % chance of obtaining a statistically significant result in the correct direction requires group sizes in the range 30–60 . For clinical relevance nearly 500 patients are required in each group . Only with an extremely effective drug ( EER>0.8 ) will we be reasonably sure of obtaining a clinical ly relevant NNT with commonly used group sizes of around 40 patients per treatment arm . The simulated trials showed substantial variation in CER and EER , with the probability of obtaining the correct values improving as group size increased . We contend that much of the variability in control and experimental event rates is due to r and om chance alone . Single small trials are unlikely to be correct . If we want to be sure of getting correct ( clinical ly relevant ) results in clinical trials we must study more patients . Credible estimates of clinical efficacy are only likely to come from large trials or from pooling multiple trials of conventional ( small ) size BACKGROUND Fibromyalgia is a chronic pain syndrome associated with sleep disorders , fatigue and psychological symptoms . Combinations therapies , such as electrotherapy and therapeutic exercises have been used in the clinical practice . AIM To assess the efficacy of high-frequency transcutaneous electrical nerve stimulation ( TENS ) as an adjuvant therapy to aerobic and stretching exercises , for the treatment of fibromyalgia . DESIGN Controlled clinical trial . SETTING Unit of rehabilitation of a public hospital . POPULATION Twenty-eight women aged 52.4±7.5 years , with fibromyalgia . METHODS A visual analogue scale measured pain intensity ; tender points pain threshold , by dolorimetry ; and quality of life , by the Fibromyalgia Impact Question naire . All subjects participated in an eight-week program consisting of aerobic exercises , followed by static stretching of muscle chains . In TENS group , high-frequency ( 150 Hz ) was applied on bilateral tender points of trapezium and supraspinatus . RESULTS TENS group had a greater pain reduction ( mean change score=-2.0±2.9 cm ) compared to Without TENS group ( -0.7±3.7 cm ) . There was a difference between mean change scores of each group for pain threshold ( right trapezium : 0.2±1 kg/cm² in TENS group and -0.2±1.2 kg/cm² in Without TENS group ) . In the evaluation of clinical ly important changes , patients receiving TENS had relevant improvement of pain , work performance , fatigue , stiffness , anxiety and depression compared to those not receiving TENS . CONCLUSION It has suggested that high-frequency TENS as an adjuvant therapy is effective in relieving pain , anxiety , fatigue , stiffness , and in improving ability to work of patients with fibromyalgia . CLINICAL REHABILITATION IMPACT High-frequency TENS may be used as a short-term complementary treatment of fibromyalgia UNLABELLED Transcutaneous electrical nerve stimulation ( TENS ) is an electrophysical modality used for pain management . This study investigated the dose response of different TENS intensities on  experimentally induced pressure pain . One hundred and thirty TENS naïve healthy individuals ( 18 - 64 years old ; 65 males , 65 females ) were r and omly allocated to 5 groups ( n = 26 per group ) :  Strong Non Painful TENS ; Sensory Threshold TENS ; Below Sensory Threshold TENS ; No Current Placebo TENS ; and Transient Placebo TENS . Active TENS ( 80 Hz ) was applied to the forearm for 30 minutes . Transient Placebo TENS was applied for 42 seconds after which the current amplitude automatically reset to 0 mA. Pressure pain thresholds ( PPT ) were recorded from 2 points on the h and and forearm before and after TENS to measure hypoalgesia . There were significant differences between groups at both the h and and forearm ( ANOVA ; P = .005 and .002 ) . At 30 minutes , there was a significant hypoalgesic effect in the Strong Non Painful TENS group compared to : Below Sensory Threshold TENS , No Current Placebo TENS and Transient Placebo TENS groups ( P < .0001 ) at the forearm ; Transient Placebo TENS and No Current Placebo TENS groups at the h and ( P = .001 ) . There was no significant difference between Strong Non Painful TENS and Sensory Threshold TENS groups . The area under the curve for the changes in PPT significantly correlated with the current amplitude ( r(2 ) = .33 , P = .003 ) . These data therefore show that there is a dose-response effect of TENS with the largest effect occurring with the highest current amplitudes . PERSPECTIVE This study shows a dose response for the intensity of TENS for pain relief with the strongest intensities showing the greatest effect ; thus , we suggest that TENS intensity should be titrated to achieve the strongest possible intensity to achieve maximum pain relief Summary Pain and fatigue during movement , but not at rest , are reduced by a onetime 30‐m treatment with active transcutaneous electrical nerve stimulation ( TENS ) in individuals with fibromyalgia . Abstract Because transcutaneous electrical nerve stimulation ( TENS ) works by reducing central excitability and activating central inhibition pathways , we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition . The current study used a double‐blinded r and omized , placebo‐controlled cross‐over design to test the effects of a single treatment of TENS with people with fibromyalgia . Three treatments were assessed in r and om order : active TENS , placebo TENS and no TENS . The following measures were assessed before and after each TENS treatment : pain and fatigue at rest and in movement ; pressure pain thresholds , 6‐m walk test , range of motion ; 5‐time sit‐to‐st and test , and single‐leg stance . Conditioned pain modulation was completed at the end of testing . There was a significant decrease in pain and fatigue with movement for active TENS compared to placebo and no TENS . Pressure pain thresholds increased at the site of TENS ( spine ) and outside the site of TENS ( leg ) when compared to placebo TENS or no TENS . During active TENS  , conditioned pain modulation was significantly stronger compared to placebo TENS and no TENS . No changes in functional tasks were observed with TENS . Thus , the current study suggests TENS has short‐term efficacy in relieving symptoms of fibromyalgia while the stimulator is active . Future clinical trials should examine the effects of repeated daily delivery of TENS , similar to the way in which TENS is used clinical ly on pain , fatigue , function , and quality of life in individuals with fibromyalgia Adequate reporting of r and omized , controlled trials ( RCTs ) is necessary to allow accurate critical appraisal of the validity and applicability of the results . The CONSORT ( Consoli date d St and ards of Reporting Trials ) Statement , a 22-item checklist and flow diagram , is intended to address this problem by improving the reporting of RCTs . However , some specific issues that apply to trials of nonpharmacologic treatments ( for example , surgery , technical interventions , devices , rehabilitation , psychotherapy , and behavioral intervention ) are not specifically addressed in the CONSORT Statement . Furthermore , considerable evidence suggests that the reporting of nonpharmacologic trials still needs improvement . Therefore , the CONSORT group developed an extension of the CONSORT Statement for trials assessing nonpharmacologic treatments . A consensus meeting of 33 experts was organized in Paris , France , in February 2006 , to develop an extension of the CONSORT Statement for trials of nonpharmacologic treatments . The participants extended 11 items from the CONSORT Statement , added 1 item , and developed a modified flow diagram . To allow adequate underst and ing and implementation of the CONSORT extension , the CONSORT group developed this elaboration and explanation document from a review of the literature to provide examples of adequate reporting . This extension , in conjunction with the main CONSORT Statement and other CONSORT extensions , should help to improve the reporting of RCTs performed in this field Fibromyalgia is characterized by a range of symptoms that include muscle pain , fatigue and sleep disorders . Transcutaneous electrical nerve stimulation ( TENS ) is an established method for pain relief . The purpose of the study was to evaluate the effectiveness and safety of the use of two simultaneously new TENS devices for fibromyalgia pain . After Ethics approval and informed consent , 39 patients were prospect ively divided into three groups to evaluate TENS device , applied simultaneously in each patient : ( 1 ) at the lower back ( perpendicular to the vertebrae canal , at the level of the 5th lumbar vertebrae ) and ( 2 ) central ly above and below the space between the C7 and T1 spinous processes . The devices were applied for 20 min at 12-h interval during 7 consecutive days . For the placebo group ( PG ) , the devices did not transmitted electrical stimulus . The single-TENS group ( STG ) ( n = 13 ) had one active and one placebo TENS . The DTG applied both active TENS devices at the low back and cervical areas . Diclofenac was used as rescue analgesic . The efficacy measures were pain relief , reduction in use of daily analgesic tablets , quality of sleep and fatigue . The evaluation within groups revealed that patients from DPG refereed no pain relief when compared to their previous VAS pain score ( 8 cm , p > 0.05 ) , while patients from the STG refereed improvement of 2.5 cm in the pain VAS ( previous 8.5 cm compared to 6 cm after treatment ) ( p < 0.05 ) , and the DPG refereed daily maintained reduction of 4 cm in the VAS pain ( previous 8.5–4.3 cm ) ( p < 0.02 ) . Concurrent daily consumption of analgesic tablets was reduced in both STG ( p < 0.05 ) and DTG ( p < 0.02 ) . Comparison among groups revealed that analgesia , as well as quality of sleep and disposition , was DTG > STG > PG ( p < 0.05 ) . Participants subjectively found the active device useful . While the application of a single active TENS improved pain relief in fibromyalgia pain , pain and fatigue were further improved when two active devices were simultaneously applied at the low back and cervical area , with no side effects The aim of this study was to investigate the results of a supervised exercise with transcutaneous electrical nerve stimulation ( TENS ) in an exercise controlled study in women with fibromyalgia . Sixty-six women with fibromyalgia who admitted to the outpatient clinic of our hospital were r and omized into two treatment groups . The patients in both groups participated in a supervised combined exercise program for 12 weeks . The women in first group had additional TENS in the first 3 weeks of the study . All subjects were analyzed at the baseline , at the end of the 3rd and 12th 
    Output:
    
There were no significant differences between TENS and placebo for pain at rest .
There was insufficient high- quality evidence to support or refute the use of TENS for fibromyalgia .