• Journal of the Korean Data and Information Science Society
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• v.22 no.3
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• pp.605-612
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• 2011

In multi-center randomized clinical trial the treatment eect may be changed over centers. It is thus important to investigate the heterogeneity in treatment eect between centers. For this, uncorrelated random-eect models assuming independence between random-eect terms have been often used, which may be a strong assumption. In this paper we propose a correlated frailty modelling approach of investigating such heterogeneity using the hierarchical-likelihood method when the outcome is time-to-event. In particular, we show how to construct a proper prediction interval for frailty, which explores graphically the potential heterogeneity for a treatment-by-center interaction term. The proposed method is illustrated via numerical studies based on data from the design of a multi-center clinical trial.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1429-1440
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• 2008

In a meta-analysis combining the results from different clinical trials, it is important to consider the possible heterogeneity in outcomes between trials. Such variations can be regarded as random effects. Thus, random-effect models such as HGLMs (hierarchical generalized linear models) are very useful. In this paper, we propose a HGLM framework for analyzing the binominal response data which may have variations in the odds-ratios between clinical trials. We also present the prediction intervals for random effects which are in practice useful to investigate the heterogeneity of the trial effects. The proposed method is illustrated with a real-data set on 22 trials about respiratory tract infections. We further demonstrate that an appropriate HGLM can be confirmed via model-selection criteria.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.79-83
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• 2002

A phase III clinical trial of a new drug for neutropenia induced by chemotherapy is presented and consider adding random effects in crossover design which was used in the clinical study. The diagnostics for its heteroscedasticity based on score statistic is derived for detecting homoscedasticity of errors in crossover design. A small simulation study is peformed to investigate the finite sample behaviour of the test statistic which is known to have an asymptotic chi-square distribution under the null hypothesis.

• Journal of Acupuncture Research
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• v.24 no.1
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• pp.127-135
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• 2007

Objectives: To evaluate the methodological quality of Korean Acupuncture Clinical trials Methods : Two independent researchers reviewed 12 protocols of Acupuncture clinical trials which were conducted in Korea 2006. Also, Survey Principal Investigator of those was conducted. We compare the results of protocol review with investigator reponses of actual practice. Quality assessment consisted of 5 items including random sequence generation, randomization method, allocation concealment, subject blinding, assessor blinding. Results : Randomization was performed using the proper procedure to insure that treatment assignment is unbiased and concealed from subjects in all clinical trials, According to protocols, 6(50%) of 12 clinical trials used computer-generated random numbers, 6(50%) remaining trials didn't describe the randomization method. Also all trials used appropriate randomization methods on the basis of the survey results: 8 trials used computer-generated random number, 2 used random table. Of 7 protocols in which allocation concealment was stated, 5(71%) reported appropriate method (Calling a central office or statisticians, Sealed opaque envelopes). However according to survey, 5(42%) of 12 trials used inappropriate allocation concealment (Keeping a master randomization list and referring to when subject entered the trial). In addition, the result of protocol review and survey response was not coincident in 5(42%) trials. Subject blinding was conducted in all except 1 clinical trials. Although 11(92%) of 12 trials were conducted using assessor blinding in actual practice, only 7(58%) reported that in protocol. Conclusion : Although randomization and blinding were conducted adequately, allocation concealment was used inadequately, Not only appropriate allocation concealment, but also every quality assessment item including randomization, blinding should be stated in more detail in protocol.

• 대한예방의학회:학술대회논문집
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• 1994.02b
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• pp.261-264
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• 1994

This paper proposes a new method for planning randomized clinical trials. This method is especially suited to comparison of a best standard or control treatment with an experimental treatment. Patients are allocated into two groups by a random or chance mechanism. Patients In the first group receive standard treatment; those in the second group are asked if they will accept the experimental therapy; if they decline. they receive the best standard treatment. In the analyses of results. all those in the second group. regardless of treatment. are compared with those in the first group. Any loss of statistical efficiency can be overcome by Increased numbers. This experimental plan is indeed a randomized clinical trial and has the advantage' that, before providing consent, a patient will know whether an experimental treatment is to be used.

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.381-389
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• 2004

Objective : To compare the efficacy between SKI306X and Diclofenac by using generalized estimating equations (GEE) methodology in the analysis of correlated bivariate binary outcome data in Osteoarthritis (OA) diseases. Methods : A randomized, double-blind, active comparator-controlled, non-inferiority clinical trial was conducted at 5 institutions in Korea with the random assignment of 248 patients aged 35 to 75 years old with OA of the knee and clinical evidence of OA. Patients were enrolled in this study if they had at least moderate pain in the affected knee joint and a score larger than 35mm as assessed by VAS (Visual Analog Scale). The main exposure variable was treatment (SKI 306X vs. Diclofenac) and other covariates were age, sex, BMI, baseline VAS, center, operation history (Yes/No), NSAIDS (Y/N), acupuncture (Y/N), herbal medicine (Y/N), past history of musculoskeletal disease (Y/N), and previous therapy related with OA (Y/N). The main study outcome was the change of VAS pain scores from baseline to the 2nd and 4th weeks after treatment. Pain scores were obtained as baseline, 2nd and 4th weeks after treatment. We applied GEE approach with empirical covariance matrix and independent(or exchangeable) working correlation matrix to evaluate the relation of several risk factors to the change of VAS pain scores with correlated binary bivariate outcomes. Results : While baseline VAS, age, and acupuncture variables had protective effects for reducing the OA pain, its treatment (Joins/Diclofenac) was not statistically significant through GEE methodology (ITT:aOR=1.37, 95% CI=(0.8200, 2.26), PP:aOR=1.47, 95% CI=(0.73, 2.95)). The goodness-of-fit statistic for GEE (6.55, p=0.68) was computed to assess the adequacy of the fitted final model. Conclusions : Both ANCOVA and GEE methods yielded non statistical significance in the evaluation of non-inferiority of the efficacy between SKI306X and Diclofenac. While VAS outcome for each visit was applied in GEE, only VAS outcome for the fourth visit was applied in ANCOVA. So the GEE methodology is more accurate for the analysis of correlated outcomes.

• Journal of Preventive Medicine and Public Health
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• v.55 no.6
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• pp.595-603
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• 2022

Objectives: Poor menstrual health may lead to school absenteeism and adverse health outcomes for adolescents. The purpose of this study was to determine the effect of pubertal and menstrual health education on health and preventive behaviors among Iranian secondary school girls. Methods: A quasi-experimental study was conducted to evaluate the effectiveness of a health intervention program. A total of 578 students (including intervention and control participants) in 12 schools in Tehran Province, Iran were included by multistage random sampling. The program comprised seven 2-hour educational sessions. After confirming the reliability and validity of a researcher-made questionnaire, that questionnaire was used to collect the required data, and the groups were followed up with after 6 months. Results: After the educational intervention, the mean scores of menstrual health-related knowledge and constructs of the theory of planned behavior were significantly higher in the intervention group than in the control group (p<0.001 for all dimensions). Conclusions: The results of this study emphasize the effectiveness of menstrual health interventions in schools. These findings should also encourage health policy-makers to take committed action to improve performance in schools.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1209-1216
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• 2015

Competing-risks events are often observed in a clustered clinical study such as a multi-center clinical trial. We propose a joint modelling approach via a shared frailty term for competing risks survival data from a cluster. For the inference we use the hierarchical likelihood (or h-likelihood), which avoids an intractable integration. We derive the corresponding h-likelihood procedure. The proposed method is illustrated via the analysis of a practical data set.

• Journal of Korean Medicine Rehabilitation
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• v.29 no.1
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• pp.63-73
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• 2019

Objectives The purpose of this study is to evaluate the safety of Ojeok-san extract powder and soft extract in healthy male volunteers. Methods Randomized controlled, cross over study was carried out in healthy male volunteers. Total 27 of 31 subjects meeting the inclusion criteria were enrolled and three subjects for waiting were included. To each group 12 subjects were randomly allocated by random number table. Group A took the extract powder in the first period and then took the soft extract in the second period. Group B took the medicine in the opposite order. Trial was conducted through two times of hospitalizations and all subjects had a seven-days of wash out period. Vital sign and laboratory test were checked before and after the medication. The mean difference of safety evaluation variables were analyzed by paired t-test (p<0.001) or wilcoxon signed rank test (p<0.05). The mean difference between two groups were analyzed by independent t-test (p<0.05) or Mann whitney test (p<0.05). Results As a result of all data related to vital sign and laboratory test in both group, There were no significant differences associated with the clinical trial drug between before and after the medication. And there was no adverse event associated with the clinical trial drug. Conclusions Both Ojeok-san extract powder and soft extract were found to be safe for healthy male volunteers.

• Korean Journal of Exercise Nutrition
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• v.25 no.1
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• pp.7-15
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• 2021

[Purpose] Sodium bicarbonate shows ergogenic potential in physical exercise and sports activities, although there is no strong evidence which performance markers show the greatest benefit from this supplement. This study evaluated the effects of sodium bicarbonate supplementation on time trial performance and time to exhaustion in athletes and sports practitioners. [Methods] A systematic review was conducted using three databases, including 17 clinical trials. Among these clinical trials, 11 were considered eligible for the meta-analysis according to the criteria for the assessment of methodological quality using the PEDro Scale. Time to exhaustion was assessed in six studies, while time trial performance was evaluated in five studies. [Results] A significant beneficial effect of supplementation on time to exhaustion was found in a random effects model (1.48; 95% confidence interval [CI], 0.49 to 2.48). There was no significant effect of supplementation on time trial performance in a fixed effects model (slope = -0.75; 95% CI, -2.04 to 0.55) relative to a placebo group. [Conclusion] Sodium bicarbonate has the potential to improve sports performance in general, especially in terms of time to exhaustion.