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Comparison of the Validity of Intention-To-Treat and Per-Protocol Approaches Using Monte-Carlo Simulation: Secondary Analysis of a Clinical Trial in the Treatment of Schizophrenic Patients in the Presence of Non-Compliance
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.


Probabilistic Carcinogen Risk Assessment from Exposure to Chromium in Drinking Water Resources in Rural Areas of Qazvin Province
Zahra Hamidi, Mehdi Ranjbaran, Fateme Qotbi Nia, Akram Bahojb, Hamid Karyab,
Volume 18, Issue 3 (12-2022)
Abstract
Background and Objectives: Chromium is a heavy metal that toxic to humans in small concentrations. This study aimed to evaluate the cancer risk of exposure to chromium in drinking water in rural areas of Qazvin province.
Methods: Water sampling was performed according to the standard methods for water and wastewater examination and chromium analysis was performed with ICP-OES. Exposure factors were determined using a validated questionnaire. Finally, the risk assessment of oral and dermal exposure to chromium was performed using the risk assessment technique. Monte Carlo simulation was also used to determine the uncertainty caused by point risk estimation.
Results: The mean concentration of chromium in drinking water was 2.8±5.04 μg/l. The excess lifetime cancer estimated by the Monte Carlo simulation was 30.8 cases per 100,000 in the studied population, indicating 100 cases of cancer in the population living in rural areas of the Qazvin province.
Conclusion: Based on the obtained results, it can be concluded that although the concentration of chromium was lower than the maximum allowed in the national standard (0.05 mg/l), the risk of carcinogenesis was higher than the acceptable risk level of WHO (1 case per 100,000). Also, using the results obtained from the Monte Carlo simulation instead of point estimation provides higher confidence in risk management decisions.

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