Iranian Journal of

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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.

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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.