Randomized clinical trials and observational studies in the assessment of drug safety

Randomized clinical trials are considered as the preferred design to assess the potential causal relationships between drugs or other medical interventions and intended effects. For this reason, randomized clinical trials are generally the basis of development programs in the life cycle of drugs and the cornerstone of evidence-based medicine. Instead, randomized clinical trials are not the design of choice for the detection and assessment of rare, delayed and/or unexpected effects related to drug safety. Moreover, the highly homogeneous populations resulting from restrictive eligibility criteria make randomized clinical trials inappropriate to describe comprehensively the safety profile of drugs. In that context, observational studies have a key added value when evaluating the benefit-risk balance of the drugs. However, observational studies are more prone to bias than randomized clinical trials and they have to be designed, conducted and reported judiciously. In this article, we discuss the strengths and limitations of randomized clinical trials and of observational studies, more particularly regarding their contribution to the knowledge of medicines’ safety profile. In addition, we present general recommendations for the sensible use of observational data.     

Bénéfices et risques d’une supplémentation en iode des femmes enceintes : une revue des études observationnelles et expérimentales en régions de carence iodée légère à modérée

BackgroundThe iodine status of the French population has been improved since 1952. As iodine requirements increase during pregnancy, the World Health Organization recommended in 2005 systematic iodine supplementation for pregnant women. Our work tried to assess the benefits and risks of iodine supplementation during pregnancy.MethodsWe reviewed the international literature from 1991 to 2011 and consulted the main references databases. Keywords were combined with boolean operators AND and OR. Selected studies were assessed with Consort grid.ResultsAmong 226 papers, 99 were original articles. After analysis, 13 studies were included in this review. A favorable trend toward iodine supplementation from pregnancy desire to the end of pregnancy was observed. Iodine supplementation may prevent psychomotor and neuro-intellectual disorders.ConclusionIodine status of pregnant women could be improved before pregnancy by more widespread use of iodized salt and iodine-enriched bread in French households. A randomized controlled trial is recommended to confirm the benefit of iodine supplementation.