***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: In symposia highlighting results from r and omized trials of antiretroviral drugs  , and in discussion sections of papers presenting such findings , a statement along the following lines is often encountered : ‘ there is no r and omized trial comparing regimens A and B but regimen A , in one trial , produced 75 % with viral load , 50 copies/ml at 48 weeks while regimen B , in a different trial , produced 85 % with , 50 copies/ml ’ . Although caution is usually expressed about making such cross-trial comparisons ( for examples [ 1–5 ] ) , the implicit message is that we have at least some evidence that regimen B is more effective than regimen A. Many of us are , at times , tempted to draw this conclusion , so it is helpful to remind ourselves of why such inferences will often be misleading A system has been constructed to evaluate the design , implementation , and analysis of  r and omized control trials ( RCT ) . The degree of quadruple blinding ( the r and omization process , the physicians and patients as to therapy , and the physicians as to ongoing results ) is considered to be the most important aspect of any trial . The analytic techniques are scored with the same emphasis as is placed on the control of bias in the planning and implementation of the studies . Description of the patient and treatment material s and the measurement of various controls of quality have less weight . An index of quality of a RCT is proposed with its pros and cons . If published papers were to approximate these principles , there would be a marked improvement in the quality of r and omized control trials . Finally , a reasonable st and ard design and conduct of trials will facilitate the interpretation of those with conflicting results and help in making valid combinations of undersized trials Multi-parameter evidence synthesis is a generalization of meta- analysis in which several parameters are estimated jointly . Here this approach is applied to a common form of data structure in which mixed pairwise comparisons are made between treatments in a ' chain of evidence ' structure . The data set investigated here , which first appeared in the confidence profile method literature , features three types of data relating to thrombolytic treatment following acute myocardial infa rct ion . There is information on reperfusion ( coronary patency ) following treatment , information on survival in reperfused and non-reperfused patients ( conditional survival ) , and independent information on the effect of treatment on survival without specifying reperfusion state ( overall survival ) . The objective of this study is to explore models for combining these three types of evidence within a single model , and some of the evidence consistency issues that arise . Bayesian Markov chain Monte Carlo methods are used to fit two models . The first , proposed in the confidence profile literature , assumes there are no differences between studies in baseline effects ( equal study effects ) . The second model assumes fixed treatment effects but allows for study differences in baseline reperfusion and conditional survival rates by assuming r and om study effects . The equal study effects model fits the data poorly , and cross-validation shows that the overall survival evidence is not consistent with the reperfusion and conditional survival evidence under this model . The evidence appears to be consistent within the more loosely structured r and om study effects model , but results are sensitive to prior assumptions about the between- study variance . The inconsistency between the three evidence types relates to overall survival , rather than to the effect of treatment on survival . Multi-parameter evidence synthesis , with suitable checks for evidence consistency , can be used to help determine whether chains of evidence ' add up ' epidemiologically within an overall model , and to construct parameter distributions for an entire model simultaneously , consistent with all the available data We devised 33 rules for the evaluation of  r and om control trials ( RCT ) and used them to assess 56 RCTs listed in Index Medicus during 1980–82 on antibiotic prophylaxis of surgical wound infection . We asked 15 questions about design and conduct , 10 about analysis and 8 about presentation . Out of a maximum score of 100 only 16 papers scored over 70 , the highest being 89 and the lowest 34 . Defects in presentation were not common , and 17 papers scored over 90 per cent . Defects in analysis included the incorrect use of statistical tests and ignoring the Type II error in ‘ negative ’ trials ; only 13 papers scored over 70 per cent . Defects in design and conduct included transgressions of ethical principles , inappropriate regimens , ill‐defined end points and biased r and omization or assessment ; only 20 papers scored over 70 per cent . We conclude that there is room for improvement in the performance of RCT and that the application of the 33 rules would be helpful not only to research ers but also to editors and referees of scientific journals , and to their readers The methodology of r and omized control trials ( RCTs ) of the primary treatment of early breast cancer has been review ed using a quantitative method . Sixty-three RCTs comparing various treatment modalities tested on over 34,000 patients and reported in 119 papers were evaluated according to a st and ardized scoring system . A percentage score was developed to assess the internal validity of a study ( referring to the quality of its design and execution ) and its external validity ( referring to presentation of information required to determine its generalizability ) . An overall score was also calculated as the combination of the two . The mean overall score for the 63 RCTs was 50 % ( 95 % confidence interval [ CI ] = 46 % to 54 % ) with small and nonstatistically significant differences between types of trial . The most common method ologic deficiencies encountered in these studies were related to the r and omization process ( only 27 of the 63 RCTs adopted a truly blinded procedure ) , the h and ling of withdrawals ( only 26 RCTs included all patients in the analyses ) , the description of the follow-up schedule ( only 12 RCTs reported adequately ) , the report of side effects ( adequate information given in 33 RCTs ) , and the description of the patient population ( satisfactory in 29 RCTs ) . Telephone calls to the principal investigators improved the quality scores by seven points on a scale of 100 , indicating that some of the deficiencies lay in reporting rather than performance . There was evidence that quality has improved over time and that the increasing tendency of involving a biostatistician in the research team was positively associated with the improvement of the internal validity but not with the external A clinical trial can not be adequately interpreted without information about the methods used in the design of the study and the analysis of the results . To determine the frequency of reporting what we consider 11 important aspects of design and analysis , we surveyed all 67 clinical trials published in the New Engl and Journal of Medicine , the Lancet , and the British Medical Journal from July through December 1979 and in the Journal of the American Medical Association from July 1979 through June 1980 . Of all 11 items in the 67 trials published in all four journals , 56 per cent were clearly reported , 10 per cent were ambiguously mentioned , and 34 per cent were not reported at all . At least 80 per cent of the 67 trials reported information about  statistical analyses , statistical methods used , and  r  and  om allocation  of subjects , yet only 19 per cent reported the method of r and omization . Loss to follow-up was discussed in 79 per cent of the articles , treatment complications in 64 per cent , and admission of subjects before allocation in 57 per cent , but eligibility criteria for admission to the trial appeared in only 37 per cent . Although information about whether patients were blind to treatment was given in 55 per cent , information about whether there was blind assessment of outcome was reported in only 30 per cent . The statistical power of the trial to detect treatment effects was discussed in only 12 per cent of the articles . The clinical trials published in The New Engl and Journal of Medicine reported 71 per cent of the 11 items , those in the Journal of the American Medical Association 63 per cent , those in the British Medical Journal 52 per cent , and those in the Lancet 46 per cent . These rates are significantly different ( P less than 0.001 ) . We recommend that editors improve the reporting of clinical trials by giving authors a list of the important items to be reported 
    Output:
    
Some valid approaches for aggregate data that could be applied using st and ard software were found : the adjusted indirect comparison , meta-regression and , for binary data only , multiple logistic regression ( fixed effect models only ) .
Simulation studies showed that the naive method is liable to bias and also produces over-precise answers .
Several methods provide correct answers if strong but unverifiable assumptions are fulfilled .
Detailed case studies comparing direct and indirect comparisons of the same effect show considerable statistical discrepancies , but the direction of such discrepancy is unpredictable .