Showing 6 results for Clinical Trial
Ar Soltanian, S Faghihzadeh, A Gerami, D Mehdibarzi, J Jing Cheng,
Volume 6, Issue 1 (6-2010)
Abstract
Background & Objectives: In clinical trials some of participants do not take assignment treatment. Intention-to-treat (ITT) is one of the strategies to analyze of clinical trials with control. ITT estimation will be invalid and incorrect to show of treatment effects in case of existing non-compliance in participants. In this study we adjusted noncompliance effect to compare of active treatment and placebo.
Methods: To demonstrate efficiency of proposed model, a dataset of crossover clinical trial with 42 patients with knee osteoarthritis was used. To estimate the non-compliance’s effect adjusting at comparison of treatment effects, we use mean of compliance proportion at periods in sequences. The parameters were estimated by maximum likelihood method. ( could you ask authors to have a look at what they wrote and compare with Farsi version)
Results: The results show that baseline variables distributions like duration of disease, severity of disease, age and sex, were not significant (p>0.05). The standard error estimation of treatment effects ( ) based on adjusted model were less than standard model (0.09 and 0.12, respectively). In addition, likelihood ratio statistics based on adjusted model were less than standard model (1177.7 versus 1205.1).
Conclusion: Based on estimation of standard errors and likelihood ratio statistics at adjusted and standard models, we observe that adjusted model is more efficient than standard model.
Ar Soltanian, M Mirfakhraei , H Mahjub, A Moghimbeigi, Sh Akhondzadeh,
Volume 10, Issue 2 (9-2014)
Abstract
Background & Objectives: The standard methods for the comparison of two drugs in a randomized controlled clinical trial in the presence of non-compliance are intention-to-treat or per-protocol approaches. Both approaches have problems with estimation of drug effects, and researchers are not still certain to adopt which one. In this study, the bias of intention-to-treat and per-protocol approaches was calculated using Monte-Carlo simulation. We tried to choose the best approach (based on the AIC index) for comparing Risperidone plus Celecoxib and Risperidone plus Placebo.
Methods: This secondary study was conducted to compare the effect of Risperidone plus Celecoxib and Risperidone plus Placebo among 60 schizophrenic patients. To choose between the intention-to-treat and per-protocol approaches, Monte-Carlo simulation with Ackaike (AIC) and Baysian (BIC) indices was used.
Results: The results of Monte-Carlo simulation showed that when the sample size was small (n=30 or n=60) under fixed conditions of non-compliance equal to 5% and 10%, intention-to-treat had a better goodness of fit than per-protocol based on AIC and BIC. However, increasing the sample size in active and placebo groups (e.g., n=100) showed that per-protocol had a better goodness of fit than intention-to-treat.
Conclusion: When the sample size is large, the per-protocol approach may have a better goodness of fit than intention-to-treat to address the effects of non-compliance in randomized clinical trials.
M Jamalian, S Kheiri,
Volume 14, Issue 4 (3-2019)
Abstract
Background and Objectives: Randomization is one of the principles of correct clinical trial. The aim of this study was to determine the quality of randomization in the published articles of clinical trials in the Persian-language journals indexed in Scopus.
ed in Scopus D
Methods: In this cross-sectional study, all clinical trials published in Persian journals indexed in Scopus during 2013-2017 were evaluated in terms of randomization using the Jadad scale. The score of the randomization item of this scale ranges from 0 to 2, with 0, 1, and 2 indicating poor, moderate, and good quality.
Results: A total of 452 articles were evaluated. Random allocation was indicated in 423 articles (93.6%). Simple random assignment and blocked methods were used in 42.8% and 22% of randomizations, respectively. The randomization method was unknown in 34% and an incorrect method was used for randomization in 5.3% of the articles. According to the Jadad scale, 56.4% of the articles had good, 36.9% had moderate, and 6.6% had poor quality in terms of randomization. Methodologists were consulted in 40.7% of the articles, and their contributions led to increased transparency in the randomization report (P = 0.007).
Conclusion: The randomization method and its report are missing in many clinical trials. Therefore, considering the importance of randomization in validating the results of these studies, journals editors and researchers should pay attention to the quality of randomization and its report.
F Fakhri, S Eybpoosh, M Solaymani Dodaran ,
Volume 15, Issue 1 (5-2019)
Abstract
Background and Objectives: A considerable number of clinical trials are conducted in Iran each year. Not much is known about the characteristics of them, this study aimed to investigate key characteristics of Iranian clinical trials.
Methods: All clinical trial protocols registered in IRCT until November 2013 were selected. Text mining techniques were used to extract information from data that was mostly in the textual format. Stata software (v. 11) was used for both extraction and analysis.
Results: Totally 5049 trials where analyzed. Trials were in 40 different areas of medicine and their annual number was increasing. The sample size of registered trials was less than 70 in most trials and showed no significant improvement during the 5-year period (Median sample size= 64, inter quartile range (IQR) = 40-100). Phase III trials comprised 8.4% of the trials with a median sample size of 75 (IQR= 50-120). Of all phase III trials, 69% had a target sample size of less than 100. Most trials used randomization techniques (87.2%) but failed to use placebo (65.3%) and double/triple-blinding techniques (55.8%). The leading sponsors for 99.9% of trials were national bodies and 92.2% of the trials received public funds. Only 1% of the trials were exclusively sponsored by pharmaceutical companies.
Conclusion: The majority of clinical trials conducted in Iran are investigator-initiated and are funded by the public sector. The small sample size and failures in bias control observed in the majority of trials highlights the need for revising current policies of conducting trials in Iran.
Z Shateri Amiri , Ss Hoseini, L Jarahi,
Volume 16, Issue 2 (8-2020)
Abstract
Background and Objectives: Clinical trials are used extensively in the compilation of systematic review studies and clinical guidelines. Critical appraisal of articles is a part of systematic review writing and also effective in citation. This study aimed to evaluate quality of randomized clinical trial articles of Mashhad University of Medical Sciences with consideration report of randomized, blindness, and allocation concealment methods in them.
Methods: In this study, all randomized clinical trials with Mashhad University of Medical Sciences affiliation indexed in PubMed by 2018 were evaluated.
Results: Of 257 eligible articles, dentistry (n=44 , 17.1%) , obstetrics and gynecology (n=28 , 10.9%) and internal medicine (n=23 , 8.9%) had the highest relative frequency of published randomized clinical trial articles. Eithy-three articles (32.3%) reported the randomization method and most of them (86.9%) used simple randomization. Blinding was done in 138 papers (53.7%) with double blinding being the most common (70.2%). Only three articles (1.2%) reported allocation concealment.
Conclusion: The report of "random allocation and randomization" in articles was far less than acceptable. It may seem that there may be different biases in the methodology. Upholding the principles of scientific writing and avoiding errors and biases increase the validity of the scientific articles and citation, which is one of the criteria of the scientific ranking of top universities.
F Varse, Sh Rimaz, Y Moradi,
Volume 16, Issue 3 (11-2020)
Abstract
Background and Objectives: Randomized clinical trials are the gold standard for evaluating the effectiveness and safety of medical interventions. Some unpredictable challenges may affect the results of these studies. Therefore, the aim of this study was to identify the challenges of clinical trial studies in different stages including design, conduct, analysis, and reporting.
Methods: This study was a qualitative study using content analysis performed from 2017 to 2019. The study population included 13 clinical trial experts who were selected through purposeful sampling. Semi-structured interviews were conducted with all subjects. Data saturation was achieved after 13 interviews.
Results: Among the 4 steps of design, conduct, analysis, and reporting, the majority of the challenges were related to conducing randomized clinical trials. Lack of knowledge of researchers, subjects, sponsors and physicians and supervisory and ethical challenges were the main challenges related to performing these studies. Poor design and lack of clinical equipoise were considered as the main challenges in the design step. Inappropriate analytical methods due to the absence of statistician in these studies were considered as the most common challenge related to analysis. Finally, lack of familiarity with international guidelines was the most important challenge in reporting.
Conclusion: There are many challenges in different steps of clinical trial studies. Therefore, additional education sessions focusing on the related guidelines and standards as well as GCP workshops for researchers can be helpful.
