***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: A common question in clinical consultations is : “ For this person , what are the likely effects of one treatment compared with another ? ” The central tenet of evidence based medicine is that this task is achieved by using the best evidence combined with consideration of that person 's individual needs.1 A further question then arises : “ What is the best evidence ? ” Two recent studies in the New Engl and Journal of Medicine have caused uproar in the research community by finding no difference in estimates of treatment effects between r and omised controlled trials and non-r and omised trials . The r and omised controlled trial and , especially , systematic review s of several of these trials are traditionally the gold st and ards for judging the benefits of treatments , mainly because it is conceptually easier to attribute any observed effect to the treatments being compared . The role of non-r and omised ( observational ) studies in evaluating treatments is contentious : deliberate choice of the treatment for each person implies that observed outcomes may be caused by differences among people being given the two treatments , rather than the treatments alone . Unrecognised confounding factors can always interfere with attempts to correct for identified differences between groups . These considerations have supported a hierarchy of evidence , with r and omised controlled trials and derivatives at the top , controlled QUESTIONS Does the PEDro scale measure only one construct ie , the method ological quality of clinical trials ? What is the hierarchy of items of the PEDro scale from least to most adhered to ? Is there any effect of year of publication of trials on item adherence ? Are PEDro scale ordinal scores equivalent to interval data ? DESIGN Rasch analysis of two independent sample s of 100 clinical trials from the PEDro data base scored using the PEDro scale . RESULTS Both sample s of PEDro data showed fit to the Rasch model with no item misfit . The  PEDro scale item hierarchy was the same in both sample s , ranging from the most adhered to item r and om allocation , to the least adhered to item therapist blinding . There was no differential item functioning by year of publication . Original PEDro ordinal scores were highly correlated with transformed PEDro interval scores ( r = 0.99 ) . CONCLUSION The PEDro scale is a valid measure of the method ological quality of clinical trials . It is valid to sum PEDro scale item scores to obtain a total score that can be treated as interval level measurement and subjected to parametric statistical analysis A controlled intervention trial , with the purpose of testing the hypothesis that the incidence of coronary heart disease ( CHD ) could be decreased by the use of a serum-cholesterol-lowering ( SCL ) diet , was carried out in two mental hospitals near Helsinki in 1959 - 71 . The subjects were hospitalized middle-aged women . One of the hospitals received the SCL diet , ie a diet low in saturated fats and cholesterol and relatively high in poly-unsaturated fats , while the other served as the control with a normal hospital diet . Six years later the diets were reversed , and the trial was continued another six years . The use of the SCL diet was associated with markedly lowered serum cholesterol values . The incidence of CHD , as measured by the appearance of certain electrocardiographic patterns and by the occurrence of coronary deaths , was in both hospitals during the SCL-diet periods lower than during the normal-diet periods . The differences , however , failed to reach statistical significance . An examination of a number of potential confounding variables indicated that the changes in them were small and failed to account for the reduction in the incidence of CHD . Although the results of this trial do not permit firm conclusions , they support the idea that also among female population s the SCL diet exerts a preventive effect on CHD A controlled intervention trial , with the purpose of testing the hypothesis that the incidence of coronary heart disease ( CHD ) could be decreased by the use of serum-cholesterol-lowering ( SCL ) diet , was carried out in 2 mental hospitals near Helsinki in 1959 - -71 . The subjects were hospitalized middle-aged men . One of the hospitals received the SCL diet , i.e. a diet low in saturated fats and cholesterol and relatively high in polyunsaturated fats , while the other served as the control with a normal hospital diet . Six years later the diets were reversed , and the trial was continued another 6 years . The use of the SCL diet was associated with markedly lowered serum-cholesterol values . The incidence of CHD , as measured by the appearance of certain electrocardiographic patterns and by the occurrence of coronary deaths , was in both hospitals during the SCL-diet periods about half that during the normal-diet periods . An examination of a number of potential confounding variables indicated that the changes in them were small and failed to account for the considerable reduction in the incidence of CHD . It is concluded that the use of the serum-cholesterol-lowering diet exerted a substantial preventive effect on CHD 
    Output:
    
There were no differences in all-cause mortality and non-significant differences in CHD mortality , result ing from the dietary interventions .
The reductions in mean serum cholesterol levels were significantly higher in the intervention groups ; this did not result in significant differences in CHD or all-cause mortality .
Dietary recommendations were introduced for 220 million US and 56 million UK citizens by 1983 , in the absence of supporting evidence from RCTs