***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 & AIMS The study objective was to determine the risk of all-cause and cause-specific mortality as well as to examine the predictors of mortality in chronic hepatitis B infection . METHODS We performed a prospect i ve cohort study of 23,820 persons ( age , 30 - 65 y ) recruited between 1991 and 1992 and followed up through 2004 from 7 townships in Taiwan . The main outcomes were all-cause and liver-related mortality rates . Mortality analyses used time-to-events methods , and survival curves were derived by the Kaplan-Meier method . Cox proportional hazard models were used to estimate multivariable-adjusted hazard ratios . RESULTS There were 1814 deaths during a mean follow-up period of 12.5 years ( 282,323.7 person-years of follow-up evaluation ) . Persons positive for hepatitis B surface antigen ( HBsAg ) had significantly ( P < .01 ) higher adjusted hazard ratios for all causes of mortality ( 1.7 ; 95 % confidence interval [ CI ] , 1.5 - 1.9 ) , liver cancer mortality ( 22.4 ; 95 % CI , 15.2 - 32.9 ) , and chronic liver disease and cirrhosis mortality ( 5.4 ; 95 % CI , 3.5 - 8.4 ) . When compared with HBsAg-negative persons , hepatitis B virus (HBV)-infected persons with HBV DNA levels less than 10(4 ) had a high risk of hepatocellular carcinoma mortality ( 4.4 ; 95 % CI , 2.4 - 8.2 ) . In HBsAg-positive persons , the mortality rate increased with cohort entry serum HBV DNA level . Liver cancer mortality ranged from 72.8 per 100,000 person-years for subjects with HBV DNA levels less than 300 copies/mL to 815.6 per 100,000 person-years for those with HBV DNA levels of 1 million copies/mL or greater . Chronic liver disease and cirrhosis deaths ranged from 9.1 to 267.4 per 100,000 person-years . CONCLUSIONS Chronic HBV infection is associated with significant preventable excess mortality risk . This mortality risk is correlated strongly with the level of viral replication among other factors Objectives : To investigate the effectiveness of screening for liver cancer in reducing mortality from the disease in a high-risk population in China . Setting : A r and omised controlled trial was carried out among men aged 30 - 69 who were chronic carriers of hepatitis-B virus ( HBsAg positive ) during the period 1989 - 1995 in Qidong county , Jiangsu Province , China . Methods : 5581 HBsAg carriers were identified by population screening and r and omly assigned to a screening group ( group A , 3712 men ) , and controls ( group B , 1869 men ) . Screening was planned to be six monthly alpha-fetoprotein ( AFP ) assays , with follow-up of subjects having an abnormal ( ≥20 μg/l ) test . All subjects were followed up for liver cancer and /or death until 31 December 1995 . Results : The overall sensitivity and specificity of the programme was 55.3 % and 86.5 % , respectively ; in subjects who complied with all scheduled screening tests , the values were 80.0 % and 80.9 % . Three hundred and seventy-four primary liver cancer ( PLC ) cases were diagnosed . The percentage of cases in stage I was significantly higher in group A ( 29.6 % ) than in group B ( 6.0 % ) . The one- , three- , and five-year relative survival rates were 23.7 % , 7.0 % , and 4.0 % in group A , and 9.7 % , 4.0 % , and 4.1 % in group B respectively , with no difference in five-year survival between the groups . The mortality rate in the screened group ( 1138 per 100,000 person-years ) was not significantly different from that in the controls ( 1114 per 100,000 ) . A Poisson regression model showed that the probability of death ( rate ratio ) in the screening group was 0.83 ( 95 % CI 0.68 - 1.03 ) relative to the control group . Conclusions : Screening with AFP result ed in earlier diagnosis of liver cancer , but the gain in lead time did not result in any overall reduction in mortality , because therapy for the patients found by screening was ineffective . Further studies using improved methods of screening , diagnosis and treatment are indicated Background Clinical evidence continues to exp and and is increasingly difficult to overview . We aim ed at conceptualizing a visual assessment tool , i.e. , a matrix for overviewing studies and their data in order to assess the clinical evidence at a glance . Methods A four-step matrix was constructed using the three dimensions of systematic error , r and om error , and design error . Matrix step I ranks the identified studies according to the dimensions of systematic errors and r and om errors . Matrix step II orders the studies according to the design errors . Matrix step III assesses the three dimensions of errors in studies . Matrix step IV assesses the size and direction of the intervention effect . Results The application of this four-step matrix is illustrated with two examples : peri-operative beta-blockade initialized in relation to surgery versus placebo for major non-cardiac surgery , and antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation .  When clinical evidence is deemed both internally and externally valid , the size of the intervention effect is to be assessed . Conclusion The error matrix provides an overview of the validity of the available evidence at a glance , and may assist in deciding which interventions to use in clinical practice OBJECTIVES To analyze sources search ed in Cochrane review s , to determine the proportion of trials included in review s that are indexed in major data bases , and to compare the quality of these trials with those from other sources . METHODS All new systematic review s in the Cochrane Library , Issue1 2001 , that were restricted to r and omized controlled trials ( RCTs ) or quasi- RCTs were selected . The sources search ed in the review s were recorded , and the trials included were checked to see whether they were indexed in four major data bases . Trials not indexed were checked to determine how they could be identified . The quality of trials found in major data bases was compared with those found from other sources . RESULTS The range in the number of data bases search ed per review ranged between one and twenty-seven . The proportion of the trials in the four data bases were Cochrane Controlled Trials Register = 78.5 % , MEDLINE = 68.8 % , Embase = 65.0 % , and Science/Social Sciences Citation Index = 60.7 % . Search ing another twenty-six data bases after Cochrane Controlled Trials Register ( CCTR ) , MEDLINE , and Embase only found 2.4 % additional trials . There was no significant difference between trials found in the CCTR , MEDLINE , and Embase compared with other trials , with respect to adequate allocation concealment or sample size . CONCLUSIONS There was a large variation between review s in the exhaustiveness of the literature search es . CCTR was the single best source of RCTs . Additional data base search ing retrieved only a small percentage of extra trials . Contacting authors and manufacturers to find unpublished trials appeared to be a more effective method of obtaining the additional better quality trials OBJECTIVE To prospect ively determine the prevalence and annual incidence of hepatocellular carcinoma in hepatitis B carriers in a heterogeneous urban North American population and to assess the diagnostic accuracy of tests used for screening for this cancer . DESIGN Prospect i ve cohort study of 1,069 chronic carriers of hepatitis B virus using screening with alpha-fetoprotein alone or in combination with ultrasonography every 6 months . RESULTS The mean age of the cohort was 39 + /- 12 years ( + /- SD ) , 65 % were men , 71 % were Asians . At the first screening visit , serum alpha-fetoprotein was > or = 20 micrograms/L in 4 % . In those subjects who were also screened by ultrasonography during the first visit , 9 % were found to have focal lesions . Only 3 subjects were found to have hepatocellular carcinoma at the first screening , giving a prevalence of 281/100,000 chronic carriers of hepatitis B virus . The cohort was followed for 2,340 person-years ( mean , 26 months follow-up , with a range from 6 to 60 months ) . During this period , 11 more subjects , 10 men and 1 woman , were diagnosed to have hepatocellular carcinoma ( annual incidence , 470/100,000 ) . In men only , the annual incidence was 657/100,000 . During the study , 5 subjects died from hepatocellular carcinoma ( annual mortality rate , 214/100,000 ) . Sensitivity and specificity of serum alpha-fetoprotein > 20 micrograms/L were 64.3 % and 91.4 % , respectively . For ultrasonography , sensitivity was 78.8 % and specificity 93.8 % . CONCLUSIONS These data suggest that the incidence and prevalence of hepatocellular carcinoma in hepatitis B carriers in our area , an urban North American setting , are as high as in countries where hepatitis B is endemic . Current screening tests have significant false-positive and false-negative rates raising questions about the cost-benefit of screening for hepatocellular carcinoma in our study population BACKGROUND The most widely accepted end point in r and omized cancer screening trials is disease-specific mortality . The validity of this end point , however , rests on the assumption that cause of death can be determined accurately . An alternative end point is all-cause mortality , which depends only on the accurate ascertainment of deaths and when they occur . We compared disease-specific and all-cause mortality in published r and omized cancer-screening trials to indirectly assess the validity of the disease-specific mortality end point . METHODS We examined all 12 published r and omized trials of cancer screening for which both end points were available ( seven of mammography , three of fecal occult blood detection , and two of chest x-ray screening for lung cancer ) . For each r and omized trial , we subtracted disease-specific mortality observed in the screened group from that observed in the control group and all-cause mortality in the screened group from that in the control group . We then compared the differences in these two mortality measures . RESULTS In five of the 12 trials , differences in the two mortality rates went in opposite directions , suggesting opposite effects of screening . In four of these five trials , disease-specific mortality was lower in the screened group than in the control group , whereas all-cause mortality was the same or higher . In two of the remaining seven trials , the mortality rate differences were in the same direction but their magnitudes were inconsistent ; i.e. , the difference in all-cause mortality exceeded the disease-specific mortality in the control group . Thus , results of seven of the 12 trials were inconsistent in their direction or magnitude . CONCLUSION Major inconsistencies were identified in disease-specific and all-cause mortality end points in r and omized cancer screening trials . Because all-cause mortality is not affected by bias in classifying the cause of death , it should be examined when interpreting the results of r and omized cancer-screening trials This study prospect ively evaluates the accuracy of contrast-enhanced ultrasound ( CEUS ) and dynamic magnetic resonance imaging ( MRI ) for the diagnosis of nodules 20 mm or smaller detected during ultrasound ( US ) surveillance . We included 89 patients with cirrhosis [ median age , 65 years ; male 53 , hepatitis C virus 68 , Child-Pugh A 80 ] without prior hepatocellular carcinoma ( HCC ) in whom US detected a small solitary nodule ( mean diameter , 14 mm ) .  Hepatic MRI , CEUS , and fine-needle biopsy ( gold st and ard ) ( FNB ) were performed at baseline . Non-HCC cases were followed ( median 23 months ) by CEUS/3 months and MRI/6 months . FNB was repeated up to 3 times and on detection of change in aspect/size . Intense arterial contrast uptake followed by washout in the delayed/venous phase was registered as conclusive for HCC . Final diagnoses were : HCC ( n = 60 ) , cholangiocarcinoma ( n = 1 ) , and benign lesions ( regenerative/dysplastic nodule , hemangioma , focal nodular hyperplasia ) ( n = 28 ) . Sex , cirrhosis cause , liver function , and alpha-fetoprotein ( AFP ) levels were similar between HCC and non-HCC groups . HCC patients were older and their nodules significantly larger ( P < 0.0001 ) . First biopsy was positive in 42 of 60 HCC patients . Sensitivity , specificity , and positive and negative predictive values of conclusive profile were 61.7 % , 96.6 % , 97.4 % , and 54.9 % , for MRI , 51.7 % , 93.1 % , 93.9 % , and 50.9 % , for CEUS . Values for coincidental conclusive findings in both techniques were 33.3 % , 100 % , 100 % , and 42 % . Thus , diagnosis of HCC 20 mm or smaller can be 
    Output:
    
The incidence of hepatocellular cancer was higher in the four-monthly screening group .
It appears that the sensitivity and specificity of the screening modes were poor , accounting for a substantial number of false-positive and false-negative screening results .
There is not enough evidence to support or refute the value of alpha-foetoprotein or ultrasound screening , or both , of hepatitis B surface antigen ( HBsAg ) positive patients for hepatocellular carcinoma .