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Biomedical subjects

F J Song

Publications and source records attributed to F J Song.

8 recordsLinked to original sources
PubMed2004

Identification and assessment of ongoing trials in health technology assessment reviews.

OBJECTIVES: To assess the importance of ongoing trials in health technology assessment reviews (HTARs) for the National Institute for Clinical Excellence and to provide practical recommendations for identifying ongoing trials and assessing their possible impact. DATA SOURCES: Electronic databases. REVIEW METHODS: Ongoing trials (or trials in progress) were defined as any trials that have started but where the results are not yet available or only interim results are available for HTARs. This methodological review included: (1) an assessment of ongoing trials in HTARs completed by the end of August 2002, (2) a survey and assessment of trial registers and other sources of ongoing trials and (3) a summary and assessment of available methods for assessing the possible impacts of ongoing trials. RESULTS: The identification of ongoing trials is a common phenomenon in reviews of health technology assessment. Twenty-three of the 32 HTARs identified one or more ongoing trials and in eight of these the information on identified ongoing trials was not considered in the evidence synthesis and research recommendations. All but one HTAR that considered the potential impact of ongoing trials adopted a narrative approach. Trial registers and grey literature are important sources of information on ongoing trials. All 32 HTARs explicitly or implicitly searched for unpublished studies, and/or ongoing trials and/or grey literature and trial registers. The assessment of six commonly used trial registers suggested that most registers provided sufficient information for reviewers to decide the relevance of identified ongoing trials. However, it is sometimes extremely difficult to know whether ongoing trials identified from different sources (registers) are the same trials or belong to the same multicentre trials. The ISRCTN (the International Standard Randomised Controlled Trial Number) is the most reliable system but it has not been widely adopted. The qualitative assessment of ongoing trials compared major features of completed and ongoing trials, providing information about the possible impact of ongoing trials in terms of relevance, validity, reliability and generalisability. Quantitative methods to assess the impact of ongoing trials include cumulative meta-analysis related methods, fail-safe N, Bayesian data monitoring, and Bayesian interim predictions. The most useful method may be the Bayesian predictive probability, which estimates predictive probabilities for any possible values of treatment effect. A case study indicated that the appropriate use of quantitative methods would strengthen findings from narrative assessment of possible impact of ongoing trials. CONCLUSIONS: Identification of ongoing trials is common in HTARs. Searching for ongoing trials in effectiveness reviews should be more thorough and explicit. Conversely, primary researchers, in particular those working with in multicentre trials, should label ongoing trials more clearly, preferably by ISRCTN. Qualitative assessment of identified ongoing trials is crucial and informative. Available quantitative methods could be used to strengthen findings from narrative assessment, although further research and more empirical examples are required. Information from ongoing trials may contribute to syntheses of results, conclusions and recommendations for future research. Future research is suggested into the identification and assessment of ongoing trials in other systematic reviews of effectiveness of health care interventions; existing and new methods for incorporating information on ongoing trials; comparing estimated impacts with the actual results of ongoing trials; and to incorporate findings from the assessment of ongoing trials into decision models.

Bayes Theorem↗
PubMed2003

Screening for fragile X syndrome: a literature review and modelling study.

OBJECTIVES: To compare the effectiveness, estimate the associated costs, and summarise available evidence about the feasibility and acceptability of different screening strategies in England and Wales. Also to establish a model for estimating effectiveness and costs of these different strategies. DATA SOURCES: Literature searches were restricted to MEDLINE and EMBASE, as well as citations in included papers. A broad search strategy was used involving all aspects of fragile X syndrome (FXS) and covered all relevant literature published between 1991 and 2001. REVIEW METHODS: An assessment was conducted of published literature and efforts focused on the development of a model that could be used to synthesise data from various sources, estimate cost-effectiveness of different strategies, and conduct sensitivity analyses according to different assumptions. RESULTS: The identified screening programmes were effective in detecting carriers, but a comparison of different strategies was not possible. Simulation results by the FXS Model showed that, over the first 10 years, 4% of premutation (PM) females and 70% of full mutation (FM) females could be detected by active cascade screening; it is 10% and 58%, respectively, by prenatal screening. The maximal detection rate for FM carriers by active cascade screening is higher than that by prenatal screening (91% versus 71%). However, the maximal rate of detection of female PM carriers by active cascade screening (6%) is much lower than that by prenatal screening (60%). During the first 10 years of simulation, the estimated direct cost per year to the NHS in England and Wales is 0.7-0.2 million pounds sterling by active cascade screening and 14.5-9.1 million pounds sterling by a programme of prenatal screening. The incremental cost per extra carrier detected (using current practice as the reference standard) is on average only 165 pounds sterling by active cascade screening and 7543 pounds sterling by prenatal screening. The incremental cost per FXS birth avoided is on average 8494 pounds sterling by active cascade screening and 284,779 pounds sterling by prenatal screening. CONCLUSIONS: The empirical evidence suggests that both prenatal screening and cascade screening are feasible and acceptable. Population-based prenatal screening is more efficacious, but it will cost more than active cascade screening. The active cascade screening of affected families is more efficient, cheaper, but less effective than a population-based prenatal screening. It is suggested that both strategies be evaluated in large-scale trials, which might also help to determine whether and how the different strategies could be simultaneously or sequentially combined.

England↗
PubMed1999

[Evidence for involvement of NO/NOS-cGMP signal system in morphine dependence].

The present study was undertaken to observe changes in cGMP contents, calcium-dependent and non-calcium-dependent NOS activities in brain regions isolated from morphine-dependent mice as well as the effect of NOS inhibitor (L-NMMA) on the development of this dependence. It was found that (1) cGMP contents in cerebellum, striatum, hippocampus and cerebral cortex were significantly decreased. (2) Calcium-dependent NOS activity was noticeably increased in striatum and cerebral cortex, which was inhibited by PKA inhibitor. No similar changes were found in cerebellum and hippocampus. Changes of non-calcium-dependent NOS activity did not occur in morphine-dependent mice brain. (3) In the striatum and cerebral cortex of morphine-dependent mice, the level of 150 kD protein phosphorylation in vitro was noticeably decreased, which was inhibited by IP20 (PKA inhibitor). (4) NOS inhibitor injected (icv) 15 min prior to daily morphine injection could prevent the development of morphine dependence. (5) All the changes above were not observed in mice treated with naloxone 30 min prior to daily morphine injection. Our data suggest that the reduction of cGMP contents and the increase of calcium-dependent NOS activity in striatum and cerebral cortex isolated from morphine-dependent mice may be mediated by opioid receptors and involved in the development of morphine-dependence. Why the increase of NOS activity was in association with the reduction of cGMP contents remains to be answered and it implies that the effect of NO/NOS involved in morphine-dependence may be produced through other mechanisms other than those producing cGMP signal. NOS phosphorylation in some other brain regions, which may be regulated by PKA, probably contributes to the increase of NOS activity in morphine-dependent mice.

Animals↗
PubMed1993

Association between HLA antigens and families with psoriasis vulgaris.

This paper typed HLA-A, B, C and DR antigens in patients with psoriasis vulgaris and healthy persons in 12 families. The phenotype frequencies of HLA-A1, B13, B17, Cw4 and Cw6 in the patients were higher than those in the controls. The analysis of haplotype segregation showed that HLA haplotypes in families with more psoriatic cases were marked deviation from random distribution. One or two HLA haplotypes sharing among affected siblings occurred more frequently than expected. The result of Lods score for six families showed that there was a close linkage between the gene of psoriasis vulgaris and HLA antigens. The gene of psoriasis was coincided with the recessive hereditary mode.

Family Health↗