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Random Effect Model (random + effect_model)
Selected AbstractsOutcome of secondary root canal treatment: a systematic review of the literatureINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2008Y.-L. Ng Abstract Aims, (i) To investigate the effects of study characteristics on the reported success rates of secondary root canal treatment (2°RCT or root canal retreatment); and (ii) to investigate the effects of clinical factors on the success of 2°RCT. Methodology, Longitudinal human clinical studies investigating outcome of 2°RCT which were published upto the end of 2006 were identified electronically (MEDLINE and Cochrane database 1966,2006 Dec, week 4). Four journals (Dental Traumatology, International Endodontic Journal, Journal of Endodontics, Oral Surgery Oral Medicine Oral Pathology Endodontics Radiology), bibliographies of all relevant papers and review articles were hand-searched. Two reviewers (Y-LN, KG) independently assessed and selected the studies based on specified inclusion criteria and extracted the data onto a pre-designed proforma, independently. The criteria were: (i) Clinical studies on 2°RCT; (ii) Stratified analyses available for 2°RCT where 1°RCT data included; (iii) Sample size given and larger than 10; (iv) At least 6-month post-operative review; (v) Success based on clinical and/or radiographic criteria (strict = absence of apical radiolucency; loose = reduction in size of radiolucency); and (vi) Overall success rate given or could be calculated from the raw data. Three strands of evidence or analyses were used to triangulate a consensus view. The reported findings from individual studies, including those excluded for quantitative analysis, were utilized for the intuitive synthesis which constituted the first strand of evidence. Secondly, the pooled weighted success rates by each study characteristic and potential prognostic factor were estimated using the random effect model. Thirdly, the effects of study characteristics and prognostic factors (expressed as odds ratios) on success rates were estimated using fixed and random effects meta-analysis with DerSimonean and Laird's methods. Meta-regression models were used to explore potential sources of statistical heterogeneity. Study characteristics considered in the meta-regression analyses were: decade of publication, study-specific criteria for success (radiographic, combined radiographic & clinical), unit of outcome measure (tooth, root), duration after treatment when assessing success (,at least 4 years' or ,<4 years'), geographic location of the study (North American, Scandinavian, other countries), and qualification of the operator (undergraduate students, postgraduate students, general dental practitioners, specialist or mixed group). Results, Of the 40 papers identified, 17 studies published between 1961 and 2005 were included; none were published in 2006. The majority of studies were retrospective (n = 12) and only five prospective. The pooled weighted success rate of 2°RCT judged by complete healing was 76.7% (95% CI 73.6%, 89.6%) and by incomplete healing, 77.2% (95% CI 61.1%, 88.1%). The success rates by ,decade of publication' and ,geographic location of study' were not significantly different at the 5% level. Eighteen clinical factors had been investigated in various combinations in previous studies. The most frequently and thoroughly investigated were ,periapical status' (n = 13), ,size of lesion' (n = 7), and ,apical extent of RF' (n = 5) which were found to be significant prognostic factors. The effect of different aspects of primary treatment history and re-treatment procedures has been poorly tested. Conclusions, The pooled estimated success rate of secondary root canal treatment was 77%. The presence of pre-operative periapical lesion, apical extent of root filling and quality of coronal restoration proved significant prognostic factors with concurrence between all three strands of evidence whilst the effects of 1°RCT history and 2°RCT protocol have been poorly investigated. [source] Outcome of secondary root canal treatment , Systematic review of the literatureINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2007Y.-L. Ng Aims, To assess the success rates of secondary root canal treatment (2oRCT) and identify factors influencing outcome. Methodology, Longitudinal clinical studies investigating outcome of 2oRCT were identified by electronic (medline) and hand searches. Inclusion criteria were data on: number of samples, those successful and definition of success. Two reviewers independently assessed the studies and extracted the data onto a proforma. The pooled weighted success rates by each potential prognostic factor were estimated using the binomial random effect model (MLwiN version 2.02) whilst their pooled effects (expressed as odds ratio) on success rates were estimated using fixed and random effects meta-analysis with DerSimonean and Laird's methods (Stata version 9.2). Meta-regression models were used to explore potential sources of statistical heterogeneity. Study characteristics considered in the meta-regression analyses were: decade of publication, study-specific criteria for success (radiographic, combined radiographic & clinical), unit of outcome measure (tooth and root), duration after treatment when assessing success (at least 4 years or shorter), geographic location of the study (North American, Scandinavian and other countries), and qualification of the operator (undergraduate students, postgraduate students, general dental practitioners, specialist or mixed group). Results, Of the 41 studies identified, 18 studies published between 1921 and 2005 were included. The majority of studies were retrospective (n = 13) and only five prospective. The pooled weighted success rate of 2oRCT judged by complete healing was 77.6% (95% CI 73.2%, 81.4%) and by incomplete healing, 77.4% (95% CI 64.1%, 86.7%). The success rates were similar by ,year of publication' and ,country of study'. Eighteen clinical factors were investigated in various combinations in previous studies. The most frequently investigated were ,periapical status' (n = 13), ,size of lesion' (n = 7), ,culture results prior to RF' (n = 5), and ,apical extent of root filling (RF)' (n = 4). The effect of different aspects of previous treatment and re-treatment technique has been poorly tested. Conclusions, The pooled weighted estimated success rate of 2oRCT was 77%, which was significantly (P , 0.001) influenced by the presence and size of pre-operative periapical lesion. The effects of existing canal content, procedural error and re-treatment technique were poorly investigated. [source] ,-Blockers protect against spontaneous bacterial peritonitis in cirrhotic patients: a meta-analysisLIVER INTERNATIONAL, Issue 8 2009Marco Senzolo Abstract Introduction: Bacterial infections have been hypothetized to be a trigger of variceal bleeding in cirrhotic patients and ,-blockers may have a protective effect by decreasing bacterial translocation, reducing portal pressure. The aim of our study was to evaluate the possible role of ,-blockers in preventing spontaneous bacterial peritonitis (SBP) in patients with liver cirrhosis and ascites. Materials and Methods: Extensive search of the literature including randomized controlled trial (RCT) and non-RCT of primary and secondary prophylaxis for variceal bleeding in cirrhotics using ,-blockers were evaluated. We performed a meta-analysis using the occurrence of SBP as endpoint in all the studies, using the random effect model. Results: Three RCT and three retrospective studies in which ,-blockers were evaluated against no treatment for the prevention of SBP in ascitic cirrhotics were included. There was a statistically significant difference of 12.1%, P<0.001 in favour of propranolol in preventing SBP, which was confirmed by sensitivity analysis evaluating only RCTs (7.8% difference). The effect was still present when haemodynamic responders were compared with non-responders. Conclusions: This analysis suggests a role of ,-blockers in preventing SBP in ascitic cirrhotics, independent of haemodynamic response. Further formal RCTs are needed to confirm this finding. [source] Original Article: A systematic review and meta-analysis of tumor necrosis factor ,-308 polymorphism and Kawasaki diseasePEDIATRICS INTERNATIONAL, Issue 4 2010Sakda Arj-Ong Abstract Background:, There have been genetic studies assessing the association between tumor necrosis factor (TNF)-,-308 and Kawasaki disease (KD) but the results have been conflicting due to lack of power. Therefore, a systematic review and meta-analysis was conducted to increase the power for identifying the association between the TNF-,-308 polymorphism and KD. Method:, Studies were identified from MEDLINE and EMBASE databases and were included if the subjects were children and the frequencies between TNF-,-308 and KD were reported. Data were pooled using a random effect model if heterogeneity between studies was present. Results:, Thirteen studies were identified however only six studies were included. The pooled prevalence of minor A allele was 5.2% (95% confidence interval [CI]: 0.1%,9.5%). Gene effect was assessed using per-allele and per-genotype approaches. The pooled odds ratio of G versus A with the random effect model was 1.13 (95%CI: 0.34,3.27). The genotype effects for GG versus GA+AA was estimated and the pooled odds ratio was 1.08 (95%CI: 0.42,2.92). Conclusion:, This review suggests a trend of association between the TNF-,-308 G-allele and KD. However, the gene effects are heterogeneous and assessing sources of heterogeneity are limited. An updated meta-analysis is needed if more studies are published. [source] Bootstrapping data with multiple levels of variationTHE CANADIAN JOURNAL OF STATISTICS, Issue 4 2008Christopher A. Field Abstract The authors consider general estimators for the mean and variance parameters in the random effect model and in the transformation model for data with multiple levels of variation. They show that these estimators have different distributions under the two models unless all the variables have Gaussian distributions. They investigate the asymptotic properties of bootstrap procedures designed for the two models. They also report simulation results and illustrate the bootstraps using data on red spruce trees. Rééchantillonnage de données à variation multiniveau Les auteurs s'intéressent à des estimateurs généraux des paramètres de moyenne et variance dans le modèle à effets aléatoires et le modèle de transformation pour des données à variation multiniveau. Ils montrent que la loi de ces estimateurs dépend du modèle sauf si toutes les variables sont gaussiennes. Ils explorent les propriétés asymptotiques de procédures bootstrap propres aux deux modèles. Ils présentent des résultats de simulation et illustrent l'emploi de ces bootstraps à l'aide de données sur l'épinette rouge. [source] | ||||||||||