• Title/Summary/Keyword: Risk of Bias

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Effect of direct-fed microbials on culturable gut microbiotas in broiler chickens: a meta-analysis of controlled trials

  • Heak, Chhaiden;Sukon, Peerapol;Sornplang, Pairat
    • Asian-Australasian Journal of Animal Sciences
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    • v.31 no.11
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    • pp.1781-1794
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    • 2018
  • Objective: This meta-analysis was conducted to evaluate the overall effect of direct-fed microbial (DFM) or probiotic supplementation on the log concentrations of culturable gut microbiota in broiler chickens. Methods: Relevant studies were collected from PubMed, SCOPUS, Poultry Science Journal, and Google Scholar. The studies included controlled trials using DFM supplementation in broiler chickens and reporting log concentrations of the culturable gut microbiota. The overall effect of DFM supplementation was determined using standardized mean difference (SMD) with a random-effects model. Subgroups were analyzed to identify pre-specified characteristics possibly associated with the heterogeneity of the results. Risk of bias and publication bias were assessed. Results: Eighteen taxa of the culturable gut microbiota were identified from 42 studies. The overall effect of DFM supplementation on the log concentrations of all 18 taxa did not differ significantly from the controls (SMD = -0.06, 95% confidence interval [-0.16, 0.04], p = 0.228, $I^2=85%$, n = 699 comparisons), but the 18 taxa could be further classified into three categories by the direction of the effect size: taxa whose log concentrations did not differ significantly from the controls (category 1), taxa whose log concentrations increased significantly with DFM supplementation (category 2), and taxa whose log concentrations decreased significantly with DFM supplementation (category 3). Category 1 comprised nine taxa, including total bacterial counts. Category 2 comprised four taxa: Bacillus, Bifidobacterium, Clostridium butyricum, and Lactobacillus. Category 3 comprised five taxa: Clostridium perfringens, coliforms, Escherichia coli, Enterococcus, and Salmonella. Some characteristics identified by the subgroup analysis were associated with result heterogeneity. Most studies, however, were present with unclear risk of bias. Publication bias was also identified. Conclusion: DFM supplementation increased the concentrations of some beneficial bacteria (e.g. Bifidobacterium and Lactobacillus) and decreased those of some detrimental bacteria (e.g. Clostridium perfringens and Salmonella) in the guts of broiler chickens.

Efficacy of ketamine in the treatment of migraines and other unspecified primary headache disorders compared to placebo and other interventions: a systematic review

  • Chah, Neysan;Jones, Mike;Milord, Steve;Al-Eryani, Kamal;Enciso, Reyes
    • Journal of Dental Anesthesia and Pain Medicine
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    • v.21 no.5
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    • pp.413-429
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    • 2021
  • Background: Migraine headaches are the second leading cause of disability worldwide and are responsible for significant morbidity, reduction in the quality of life, and loss of productivity on a global scale. The purpose of this systematic review and meta-analysis was to evaluate the efficacy of ketamine on migraines and other primary headache disorders compared to placebo and other active interventions, such as midazolam, metoclopramide/diphenhydramine, and prochlorperazine/diphenhydramine. Methods: An electronic search of databases published up to February 2021, including Medline via PubMed, EMBASE, Web of Science, and Cochrane Library, a hand search of the bibliographies of the included studies, as well as literature and systematic reviews found through the search was conducted to identify randomized controlled trials (RCTs) investigating ketamine in the treatment of migraine/headache disorders compared to the placebo. The authors assessed the risk of bias according to the Cochrane Handbook guidelines. Results: The initial search strategy yielded 398 unduplicated references, which were independently assessed by three review authors. After evaluation, this number was reduced to five RCTs (two unclear risk of bias and three high risk of bias). The total number of patients in all the studies was 193. Due to the high risk of bias, small sample size, heterogeneity of the outcomes reported, and heterogeneity of the comparison groups, the quality of the evidence was very low. One RCT reported that intranasal ketamine was superior to intranasal midazolam in improving the aura attack severity, but not duration, while another reported that intranasal ketamine was not superior to metoclopramide and diphenhydramine in reducing the headache severity. In one trial, subcutaneous ketamine was superior to saline in migraine severity reduction; however, intravenous (I.V.) ketamine was inferior to I.V. prochlorperazine and diphenhydramine in another study. Conclusion: Further double-blind controlled studies are needed to assess the efficacy of ketamine in treating acute and chronic refractory migraines and other primary headaches using intranasal and subcutaneous routes. These studies should include a long-term follow-up and different ketamine dosages in diagnosed patients following international standards for diagnosing headache/migraine.

The Effectiveness and Safety of Acupuncture for Recovery of Patients with Vertebral Compression Fractures: A Systematic Review and Meta-analysis (척추 압박 골절 환자의 회복에 대한 침 치료의 유효성 및 안전성 평가: 체계적 문헌 고찰과 메타분석)

  • Bae, Ji min;Lee, Myeong su;Choi, Ji won;Yang, Gi young;Kim, Kun hyung
    • Korean Journal of Acupuncture
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    • v.36 no.1
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    • pp.1-18
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    • 2019
  • Objectives : The purpose of this study was to evaluate the effectiveness and safety of acupuncture treatment for recovery of patients with vertebral compression fracture(VCF). Methods : We searched ten English and Chinese and seven Korean database up to April 2018. Randomised controlled trials(RCTs), quasi-RCTs, non-radomised Controlled Trials(CCTs) were eligible. Quasi-RCTs and CCTs were assessed only for safety assessment. Pain and adverse events were primary outcome of this review. Quality of life, dysfunction, patient satisfaction, incidence of new vertebral compression fracture were regarded as secondary outcomes. The risk of bias was assessed by two independent authors using the Cochrane risk of bias tool. Level of evidence was tabulated using the GRADE methods. Results : Of 1656 screened, 15 RCTs, 1 quasi-RCT and 3 CCTs were included. Number of participants per study ranged from 45 to 135. Most of the studies had unclear or high risk of bias and considerable heterogeneity in terms of type of intervention, comparison and time-points for outcome measurement. Compared to usual care alone, acupuncture combined with usual care showed short-term favorable results for pain relief in patients with VCF(5 studies, n=252, MD -1.05 point on a 0 to 10 point scale, 95% CI -1.45 to -0.65, $I^2=74%$). Four studies reported mild and temporary adverse events, and no serious adverse events were reported. One study descriptively reported that acupuncture was effective for improving quality of life without providing numerical outcomes. There were no reports of patient satisfaction and incidence of new VCF. Conclusions : Level of evidence is very low for the effectiveness and safety of acupuncture for pain, harms and other clinical outcomes in patients with VCF. Included studies suffered from incomplete reporting, high or unclear risk of bias and substantial heterogeneity between studies. Future high-quality RCTs are needed to assess whether acupuncture is beneficial for recovery of patients with VCF.

Effectiveness of Acupotomy for Migraine: A Systematic Review (편두통의 침도 치료에 대한 체계적 문헌고찰)

  • Seok-Hee Jeon;Soo-Min Jeong;Jeong-Cheol Shin
    • Korean Journal of Acupuncture
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    • v.40 no.3
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    • pp.62-78
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    • 2023
  • Objectives : This study aims to assess the impact of acupotomy on migraine through an examination of clinical studies conducted since 2015. Methods : We conducted a comprehensive search for randomized controlled trials (RCTs) and non-randomized controlled trials (nRCTs) related to acupotomy treatment for migraine, utilizing five Korean online databases (OASIS, Science ON, DBPIA, KISS, RISS), as well as four foreign online databases (CNKI, PubMed, EMBASE, Cochrane Library). We identified a total of 10 relevant studies for analysis. Participants characteristics, treatment points, combination treatments, treatment cycles or frequencies, evaluation indices, efficacy, and adverse events were analyzed. The risk of bias in the 10 RCTs was assessed using the Revised Cochrane risk-of-bias tool for randomized trials (RoB 2.0). Results : A total of 931 participants were included in 10 studies. In the intervention group, the average duration of migraine morbidity ranged from 15.5±4.5 months to 15.9±4.2 years. Six studies based their diagnoses on the International Classification of Headache Disorders (ICHD), while five studies relied on Chinese diagnostic criteria. All studies specified the treatment area as the region exhibiting tenderness or induration on the head and neck. Treatment cycles ranged from a minimum of 2 days to a maximum of 1 week, with the number of days per treatment course varied from 5 days to 4 weeks. The diameter of acupuncture needles used varied between 0.3 mm and 1 mm. Of the eight studies specifying needle length, the shortest was 20 mm, and the longest was 40 mm. A total of eight evaluation indices were employed, with total efficacy rate (TER) and visual analogue scale (VAS) being the most frequently used. Statistically, all intervention groups showed more significant results compared to the control groups. Adverse events were reported in only two studies within the intervention group. Overall, the risk of bias assessment for the selected RCTs ranged from 'some concerns' to 'high risk of bias.' Conclusions : This study showed that acupotomy treatments for migraine were effective.

Acceptable Values of Kappa for Comparison of Two Groups

  • Seigel Daniel G.;Podgor Marvin J.;Remaley Nancy A.
    • 대한예방의학회:학술대회논문집
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    • 1994.02b
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    • pp.129-136
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    • 1994
  • A model was developed for a simple clinical trial in which graders had defined probabilities of misclassifying pathologic material to disease present or absent. The authors compared Kappa between graders, and efficiency and bias in the clinical trial in the presence of misclassification. Though related to bias and efficiency, Kappa did not predict these two statistics well. These results pertain generally to evaluation of systems for encoding medical information, and the relevance of Kappa in determining whether such systems are ready for use in comparative studies. The authors conclude that, by itself, Kappa is not informative Enough to evaluate the appropriateness of a grading scheme for comparative studies. Additional, and perhaps difficult, questions must be addressed for such evaluation.

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Depression and the Risk of Breast Cancer: A Meta-Analysis of Cohort Studies

  • Sun, Hui-Lian;Dong, Xiao-Xin;Cong, Ying-Jie;Gan, Yong;Deng, Jian;Cao, Shi-Yi;Lu, Zu-Xun
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.8
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    • pp.3233-3239
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    • 2015
  • Background: Whether depression causes increased risk of the development of breast cancer has long been debated. We conducted an updated meta-analysis of cohort studies to assess the association between depression and risk of breast cancer. Materials and Methods: Relevant literature was searched from Medline, Embase, Web of Science (up to April 2014) as well as manual searches of reference lists of selected publications. Cohort studies on the association between depression and breast cancer were included. Data abstraction and quality assessment were conducted independently by two authors. Random-effect model was used to compute the pooled risk estimate. Visual inspection of a funnel plot, Begg rank correlation test and Egger linear regression test were used to evaluate the publication bias. Results: We identified eleven cohort studies (182,241 participants, 2,353 cases) with a follow-up duration ranging from 5 to 38 years. The pooled adjusted RR was 1.13(95% CI: 0.94 to 1.36; $I^2=67.2%$, p=0.001). The association between the risk of breast cancer and depression was consistent across subgroups. Visual inspection of funnel plot and Begg's and Egger's tests indicated no evidence of publication bias. Regarding limitations, a one-time assessment of depression with no measure of duration weakens the test of hypothesis. In addition, 8 different scales were used for the measurement of depression, potentially adding to the multiple conceptual problems concerned with the definition of depression. Conclusions: Available epidemiological evidence is insufficient to support a positive association between depression and breast cancer.

Periodontal health status, oral microbiome, white-spot lesions and oral health related to quality of life-clear aligners versus fixed appliances: A systematic review, meta-analysis and meta-regression

  • Ana Sandra Llera-Romero;Milagros Adobes-Martin;Jose Enrique Iranzo-Cortes;Jose Maria Montiel-Company;Daniele Garcovich
    • The korean journal of orthodontics
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    • v.53 no.6
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    • pp.374-392
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    • 2023
  • Objective: Assess and evaluate the different indicators of oral health-related quality of life (OHRQoL) among patients treated with clear aligners (CAs) versus those treated with conventional fixed orthodontics (FAs). Methods: An electronic search was performed on the database is Web of Science, Scopus, and Embase databases. Randomized and non-randomized control trials, cross-sectional, prospective cohort and retrospective trials were included. Quality was assessed with risk of bias tool and risk of bias in non-randomised studies. Meta-analyses were performed with random effects models, estimating the standardized and non-standardized mean differences, odds ratio and risk ratio as the measure of effect. The effect on time was determined using a meta-regression model. Results: Thirty one articles were included in the qualitative synthesis and 17 in the meta-analysis. CAs had a significantly lower negative impact on QoL, with an "important" effect size, while the influence of time was not significant. Periodontal indicators plaque index (PI), gingival index (GI), probing depth (PD), and bleeding on probing show significantly better values in patients treated with CAs, with moderate to large effect sizes. PI and GI have a significant tendency to improve over time. In microbiological indicators, CAs present a lower biofilm mass without differences in the percentage of patients with high counts of Streptococcus mutans and Lactobacilli bacteria. The risk of white spot lesion onset is ten times lower in carriers of CAs. Conclusions: Patients wearing CAs show better periodontal indicators, less risk of white spot development, less biofilm mass and a better QoL than patients with FAs.

A Study on Uncertainty of Risk of Failure Based on Gumbel Distribution (Gumbel 분포형을 이용한 위험도에 관한 불확실성 해석)

  • Heo Jun-Haeng;Lee Dong-Jin;Shin Hong-Joon;Nam Woo-Sung
    • Journal of Korea Water Resources Association
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    • v.39 no.8 s.169
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    • pp.659-668
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    • 2006
  • The uncertainty of the risk of failure of hydraulic structures can be determined by estimating the variance of the risk of failure based on the methods of moments, probability weighted moments, and maximum likelihood assuming that the underlying model is the Gumbel distribution. In this paper, the variance of the risk of failure was derived. Monte Carlo simulation was peformed to verify the characteristics of the derived formulas for various sample size, design life, nonexceedance probability, and variation coefficient. As the results, PWM showed the smallest relative bias and root mean square error than the others while ML showed the smallest ones for relatively large sample siBes regardless of design life and nonexceedance probability. Also, it was found that variation coefficient does not effect on the relative bias and relative root mean square error.

Does a Debiasing Manipulation Reduce Over-estimation of Emotional Reaction to Risky Objects? (위험 대상에 대한 충격 편향은 탈 편향 조작에 의해 감소하는가?)

  • Yoon, Ji-Won;Lee, Young-Ai
    • Korean Journal of Cognitive Science
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    • v.22 no.1
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    • pp.39-55
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    • 2011
  • People tend to overestimate their emotional reactions to events such as physical handicap and buying a new car in the future. Students overestimate their reactions to a future grade as compared to their reactions after receiving the grade. Impact bias refers to people's tendency to overestimate the intensity and the duration of emotional reactions to a future event. The present study explored whether impact bias occurs to risky objects such as nuclear energy, genetically engineered food, and mobile phone. Participants were asked to predict their emotional reactions at three time points, that is, at the present, a week after, and a year after. They predicted their reactions before and after two debiasing tasks. The present study demonstrated a different pattern of impact bias at three time points: A largest bias was observed a week after the present. A defocalism manipulation has eliminated the impact bias whereas an adaptation manipulation has not. Several points were discussed regarding the difference between the previous and the present work.

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Computational procedures for exponential life model incorporating Bayes and shrinkage techniques

  • Al-Hemyari, Zuhair A.;Al-Dabag, H.A.;Al-Humairi, Ali Z.
    • International Journal of Reliability and Applications
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    • v.16 no.2
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    • pp.55-79
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    • 2015
  • It is well known that using any additional information in the estimation of unknown parameters with new sample of observations diminishes the sampling units needed and minimizes the risk of new estimators. There are many rational reasons to assure that the existence of additional information in practice and there exists many practical cases in which additional information is available in the form of target value (initial value) about the unknown parameters. This article is described the problem of how the prior initial value about the unknown parameters can be utilized and combined with classical Bayes estimator to get a new combination of Bayes estimator and prior value to improve the properties of the new combination. In this article, two classes of Bayes-shrinkage and preliminary test Bayes-shrinkage estimators are proposed for the scale parameter of exponential distribution. The bias, risk and risk ratio expressions are derived and studied. The performance of the proposed classes of estimators is studied for different choices of constants engaged in the estimators. The comparisons, conclusions and recommendations are demonstrated.