***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: 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 Abstract A previously established relationship for deriving dichotomous from continuous information in r and omised controlled trials ( RCTs ) of analgesics has been tested using an independent data set . Individual patient information from 18 RCTs of parallel‐group design in acute postoperative pain ( after abdominal , gynaecological and oral surgery ) was used to calculate the percentage of the maximum possible pain relief score  ( % maxTOTPAR ) and the proportion of patients with > 50%maxTOTPAR for the different treatments . The relationship between the measures was investigated in 85 treatments with over 3400 patients . In 80 of 85 treatments ( 94 % ) agreement between calculated and actual number of patients with > 50%maxTOTPAR was within four patients per treatment and in 72 ( 85 % ) was within three ( average of 40 patients per treatment , range 21–58 patients ) . Summing the positive and negative differences between actual and calculated numbers of patients with > 50%maxTOTPAR gave an average difference of 0.30 patients per treatment arm . Reports of RCTs of analgesics frequently describe results of studies in the form of mean derived indices , rather than using discontinuous events , such as number or proportion of patients with 50 % pain relief . Because mean data inadequately describe information with a non‐normal distribution , combining mean data in systematic review s may compromise the results . Showing that dichotomous data can reliably be derived from mean data in acute pain studies enables data published as means to be used for quantitative systematic review s which require data in dichotomous form & NA ; Reports of RCTs of analgesics frequently describe results of studies in the form of mean derived indices , rather than using discontinuous events — such as number or proportion of patients with 50 % pain relief . Because mean data inadequately describe information with a non‐normal distribution , combining mean data in systematic review s may compromise the results . Showing that dichotomous data can reliably be derived from mean data , at least in acute pain models , indicates that more meaningful overviews or meta‐ analysis may be possible . This study investigated the relationship between continuous and dichotomous analgesic measures in a set of individual patient data , and then used that relationship to derive dichotomous from continuous information in r and omised controlled trials ( RCTs ) of analgesics .  Individual patient information from 13 RCTs of parallel‐group and crossover design in acute postoperative pain was used to calculate the percentage of the maximum possible pain relief score ( % maxTOTPAR ) and the proportion of patients with greater than 50 % pain relief ( > 50%maxTOTPAR ) for the different treatments . The relationship between the measures was investigated in 45 actual treatments and 10 000 treatments simulated using the underlying actual distribution ; 1283 patients had 45 separate treatments . Mean % maxTOTPAR correlated with the proportion of patients with > 50%maxTOTPAR ( r2 = 0.90 ) . The relationship calculated from all the 45 treatments predicted to within three patients the number of patients with more than 50 % pain relief in 42 of 45 treatments , and 98.8 % of 10 000 simulated treatments . For seven effective treatments , actual numbers‐needed‐to‐treat ( NNT ) to achieve > 50%maxTOTPAR compared with placebo were very similar to those derived from calculated data & NA ; A data base of r and omised  clinical trials ( RCTs ) in pain research published from 1950 to 1990 was created following an extensive literature search . By applying a refined MEDLINE search strategy from 1966 to 1990 and by h and ‐ search ing more than 1 000 000 pages of a total of 40 biomedical journals published during the period 1950–1990 , more than 8000 RCTs were identified . The RCTs were published in more than 800 journals and over 85 % appeared between 1976 and 1990 . If the trend of the last 15 years persists , a total of more than 15 000 RCTs will be published in pain relief by the year 2000 . A detailed description of methods to ensure efficient use of re sources during the identification , retrieval and management of the information in pain relief and other fields is given . Emphasis is made on the importance of refining MEDLINE search strategies , on the use of volunteers to h and ‐ search journals and on careful monitoring of each of the steps of the process . The potential uses of the data base to guide clinical and research decisions are discussed Abstract One way to ensure adequate sensitivity for analgesic trials is to test the intervention on patients who have established pain of moderate to severe intensity . The usual criterion is at least moderate pain on a categorical pain intensity scale . When visual analogue scales ( VAS ) are the only pain measure in trials we need to know what point on a VAS represents moderate pain , so that these trials can be included in meta‐ analysis when baseline pain of at least moderate intensity is an inclusion criterion . To investigate this we used individual patient data from 1080 patients from r and omised controlled trials of various analgesics .  Baseline pain was measured using a 4‐point categorical pain intensity scale and a pain intensity VAS under identical conditions . The distribution of the VAS scores was examined for 736 patients reporting moderate pain and for 344 reporting severe pain .  The VAS scores corresponding to moderate or severe pain were also examined by gender . Baseline VAS scores recorded by patients reporting moderate pain were significantly different from those of patients reporting severe pain . Of the patients reporting moderate pain 85 % scored over 30 mm on the corresponding VAS , with a mean score of 49 mm . For those reporting severe pain 85 % scored over 54 mm with a mean score of 75 mm . There was no difference between the corresponding VAS scores of men and women . Our results indicate that if a patient records a baseline VAS score in excess of 30 mm they would probably have recorded at least moderate pain on a 4‐point categorical scale 
    Output:
    
AUTHORS ' CONCLUSIONS In the absence of evidence of efficacy , at present , for oral nabumetone in acute postoperative pain , its use in this indication is not justified .