Liver fibrosis in chronic liver disease refers to the body’s repair response to sustained repeated necrosis or inflammation of liver cells, which results in fibrosis accompanied by relative or absolute lack of fiber degradation and deposition of extracellular matrix in the liver. Early and timely diagnosis and treatment of hepatic fibrosis are of great importance to patients with liver disease. A rational and complete diagnostic model of liver fibrosis should involve clinical pathology and histology, imaging, and serum biochemical markers. Liver biopsy has been regarded as the "gold standard" for the diagnosis of liver fibrosis and as a reference standard for other non-invasive diagnostic tests of liver fibrosis. Since it is invasive, liver biopsy is difficult to implement in clinical practice and a second liver biopsy is even more difficult. As for the non-invasive diagnosis of liver fibrosis, clinical symptoms and signs are not specific. The sensitivity and specificity of individual serum biochemical markers are still very weak, and imaging studies also lack specificity. The mathematical model “FibroTest” of serum biochemical markers has better diagnostic accuracy, but the calculation is complicated, making it difficult to achieve widespread use. There is insufficient evidence to suggest that the "gold standard" of liver biopsy can be replaced. Therefore, further research is needed to investigate how best to balance the benefits and harms of different tests, to identify the best combination, to simplify any calculation steps, to reduce costs, to avoid liver biopsy, and to find new, more specific and sensitive markers.
Some statistical measures in evidence-based medicine, such as RRR, ARR and NNTwere introduced.
In this paper, we introduce theory and practice method about combining independent studies of Diagnostic test into a summary ROC curve. This is a useful and easily applied by clinicians to analyse the data of diagnostic test. It’s referance for user and doer of EBM in China.
We described our understanding of EBM, the ‘three principles＇ and ‘five steps＇ to practice it. EBM is an embodiment of human moral rule and axiom in clinical medicine; it is an advanced clinical model and medical practical methodology; it results from a basis of developed and perfected clinical research methodology, best evidence database, information technology. We also discussed the relationship between EBM and traditional Chinese medicine （TCM） modernization. The definition of modernization of TCM was suggested as scientifical standardization and internationalization. TCM theory in fact is not a basic but a clinical practice theory. EBM model should become the standard model of TCM practice to accelarate the standardization of TCM diagnostic technique and therapy. The key is not try to explain TCM theories with modern medical theroies, but work out common effectiveness evaluation criteria. Only when the effectiveness is intemationally acknowledged, can TCM be internationalized.
In this paper, we introduce meaning and purpose of confidence interval (CI) in evidence-based medicine, For example, RRR ,ARR ,NNT. It s referance for user and doer of EBM in China.
A mean of systematic review of diagnostic tests based on The Bayes Library of Diagnostic Studies and Reviews (2nd edition 2002) and Bayes Library are introduced to Chinese readers who are interesting on diagnostic test and screening systematic review.
In this paper , the statistic significance and clinical application of forest plots in a meta-analysis have been fully discussed. If the horizontal line represents the 95% confidence interval of the indexes including odds ratio, relative risk, weighted mean difference, and standard mean difference crosses the vertical line, the effect of test group is not signficant with that of control group; if the horizontal line lies to the right of the vertical line, it indicates that the test group is significantly effctive. If the horizontal line lies to the left of the vertical line, it indicates that the control group is more effective. In addition, it doesn’t mean that clinical application is more beneficial, if the treatment study has more effect, because experimental factor can be positive or negative.
NNT defines the number of patients who need to be treated in order to achieve one additional favorable outcome, and NNH is defined as the number of patients who must be treated with a therapy in order to have one additional patient suffer an adverse effect compared with the control treatment. This is the most important thing that should beconsidered before administering a treatment. NNT can also be used to assess the relative benefit or harm in the comparison of intervention versus positive control. If the effect is smaller in the intervention group than that in the control group, NNT should be used; if the effect is bigger in the intervention group than that in the control group, NNH should be used. When comparison is made between an intervention versus placebo, NNT and NNH are absolute outcomes; when an intervention is compared to a positive control, NNT and NNH are relative outcomes. RR or OR or RD may help to judge which comparator has bigger or smaller effect, and whether NNT or NNH should be used.
Backgroud Iodine deficiency is the main cause for potentially preventable mental retardation in childhood and is still prevalent in large parts of the world. Objectives To assess the effects of iodised salt in comparison with other forms of iodine supplementation or placebo in the prevention of iodine deficiency disorders.Search strategy We searched the Cochrane Library, Medline, the Register of Chinese trials developed by the Chinese Cochrane Centre, and the Chinese Med Database. We performed handsearching of a number of journals (Chinese Journal of Control of Endemic Diseases, Chinese Journal of Epidemiology, Chinese Journal of Preventive Medicine, and Studies of Trace Elements and Health up to February 2001), and searched reference lists, databases of ongoing trials and the Internet. Date of latest search: November 2001. Selection Criteria We included prospective controlled studies of iodised salt versus other forms of iodine supplementation or placebo in people living in areas of iodine deficiency. Studies reported mainly goitre rates and urinary iodine excretion as outcome measures. Data collection amp; analysis As the studies identified were not sufficiently similar and not of sufficient quality, we did not do a meta-analysis but summarised the data in a narrative format. Main results We found six prospective controlled trials relating to our question. Four of these were described as randomised controlled trials, one was a prospective trial that did not specify allocation to comparison groups, and one was a large population-based study comparing different interventions. Comparison interventions included non-iodised salt, iodised water, iodised oil, iodation with potassium iodide versus potassium iodate. Numbers of participants in the trials ranged from 35 to 334; over 20 000 people were included in the population-based study. There was a tendency towards goitre reduction with iodised salt, although this was not significant in all studies. There was aim an improved iodine status in most studies (except in small children in one of the studies), although urinary iodine excretion did not always reach the levels recommended by the WHO. Reviewers’ conclusions The results suggest that iodised salt is an effective and safe means of improving iodine status. However, high quality controlled studies are needed to address questions of dosage and best means of iodine supplementation in different population groups.
Objective To evaluate the quality of studies assessing the value of serum hyaluronic acid in the diagnosis of liver fibrosis, to analyze the sources of bias and variation, and to estimate the accuracy of serum hyaluronic acid in diagnosing early liver cirrhosis and liver fibrosis in patients with chronic viral hepatitis.Methods We searched MEDLINE (1966 to June 2006), EMbase (1974 to June 2006), CBMdisc (1978 to April 2005), CNKI (2005 to June 2006) and VIP (2005 to June 2006) for studies assessing the diagnostic value of serum hyaluronic acid for liver fibrosis in patients with chronic viral hepatitis. We checked the references in the reports of included studies. QUADAS items were used for quality assessment. Meta-disc software was used to analyze sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic test odds ratio for the pooled analysis and heterogeneity test. DPS2005 software was used to draw SROC curves for those without heterogeneity. Results In total 24 studies were included: 12 published in Chinese and 12 published in English. Results of the pooled analysis showed that, as for radioimmunoassay (RIA), the pooled LR+ of the studies involving the diagnosis of liver cirrhosis and the differentiation of absent/present liver fibrosis were 7.029 and 3.608; and the pooled LR- were 0.198 and 0.319, respectively. As for enzyme-linked immunosorbent assay (ELISA), the pooled LR+ of the studies involving the diagnosis of liver cirrhosis, the differentiation of mild/severe and absent/present liver fibrosis were 6.093, 9.806 and 4.308; and the pooled LR- were 0.354, 0.347 and 0.563, respectively. Conclusion The biases identified from the 24 studies are mainly due to reference standard review bias. By both RIA and ELISA methods, serum hyaluronic acid has a sound value in diagnosing live cirrhosis. Its value in differentiating absent/present liver fibrosis is also acceptable. However, its value in differentiating mild/severe liver fibrosis needs to be further studied.