Validity Of Randomized Controlled Trials Research Articles

Identification of tools used to assess the external validity of randomized controlled trials in reviews: a systematic review of measurement properties

BackgroundInternal and external validity are the most relevant components when critically appraising randomized controlled trials (RCTs) for systematic reviews. However, there is no gold standard to assess external validity. This might be related to the heterogeneity of the terminology as well as to unclear evidence of the measurement properties of available tools. The aim of this review was to identify tools to assess the external validity of RCTs. It was further, to evaluate the quality of identified tools and to recommend the use of individual tools to assess the external validity of RCTs in future systematic reviews.MethodsA two-phase systematic literature search was performed in four databases: PubMed, Scopus, PsycINFO via OVID, and CINAHL via EBSCO. First, tools to assess the external validity of RCTs were identified. Second, studies investigating the measurement properties of these tools were selected. The measurement properties of each included tool were appraised using an adapted version of the COnsensus based Standards for the selection of health Measurement INstruments (COSMIN) guidelines.Results38 publications reporting on the development or validation of 28 included tools were included. For 61% (17/28) of the included tools, there was no evidence for measurement properties. For the remaining tools, reliability was the most frequently assessed property. Reliability was judged as “sufficient” for three tools (very low certainty of evidence). Content validity was rated as “sufficient” for one tool (moderate certainty of evidence).ConclusionsBased on these results, no available tool can be fully recommended to assess the external validity of RCTs in systematic reviews. Several steps are required to overcome the identified difficulties to either adapt and validate available tools or to develop a better suitable tool.Trial registrationProspective registration at Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/PTG4D.

Withdrawal reasons of randomized controlled trials on type 2 diabetes: a systematic review.

Type 2 diabetes mellitus (T2DM) is the subject of numerous randomized controlled trials (RCTs). The validity of RCTs may be threatened by attrition bias due to the discontinuation of the study. The aim of this systematic review is to evaluate the reasons of patient's withdrawal from these RCTs. A systematic literature search on PubMed, Cochrane Library, Web of Science, and Scopus databases was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram. The aim was to obtain all relevant blinded RCTs published before January 2017 in which the effectiveness of synthetic drugs, vitamins/minerals were compared to that of placebo or active control in T2DM. The quality of RCTs was assessed using the Jadad score. The frequency of withdrawal reasons was presented based on treatments with placebo/active control, national/international level of the studies, and publication year. Meta-analysis was not performed due to the heterogeneity. Overall, 1368 articles comprising of 640,780 subjects were included. In the majority of the RCTs (75.0%), the intervention and the placebo arms were compared. Most of the included studies (96%) were classified in the high-quality category (Jadad score≥3). The highest proportion of reported withdrawal cases was found in international studies, national RCTs conducted in Japan, and RCTs published in 2011. The withdrawal reasons were reported for 91,669 (63.75%) of the total 143,794 participants who had withdrawn from these studies. The main reported reasons were "adverse effects" (24.04%), "withdraw consent" (16.10%), and "missing data" (11.08%). Variations in the reported withdrawal reasons were based on the country or published year. RCTs with triple blinded design as well as those in which anti-hyperlipidemia and anti-obesity medications were applied, showed significantly higher probability of reported the withdrawal. High proportion of reported discontinuation in blinded RCTs on patients with T2DM was related to drug adverse effects. Overall, the total number and reason of drop out were unsatisfactory.

Ethical Issues in HIV/STD Prevention Research With High Risk Youth: Providing Help, Preserving Validity

Many preventive intervention studies with adolescents address high-risk behaviors such as drug and alcohol use, and unprotected sex. Randomized controlled trials (RCT) are the gold standard methodology used to test the effectiveness of these behavioral interventions. Interventions outside the rigidly described protocol are prohibited. However, there are ethical challenges to implementing inflexible intervention protocols, especially when the target population is young, experiences many stressful events, and lives in a resource-poor environment. Teens who are at high risk for substance use or sexual risk behaviors tend to be at risk for other problems such as exposure to violence, sexual and physical abuse, depression, and homelessness. How should investigators deal with the psychological and social needs of teenagers in prevention programs in an ethically appropriate way and at the same time preserve the validity of RCT results? We have identified program characteristics, participant characteristics, interaction with parents, and problems with adolescents not in the study as sources of ethical dilemmas in RCT with at-risk adolescents. As a result of our experience, we recommend that every behavioral intervention study develop an ethics protocol, which should include rules for providing help to participants, has contact information for experts to provide guidance, and an emergency procedure for dealing with life threatening situations. In addition, studies should have a resource manual, train research staff in these ethical issues, and work with a data safety and monitoring board or ethics committee.

Avoiding Bias in Randomised Controlled Trials in Educational Research

Randomised controlled trials (RCTs) are often seen as the ‘gold standard’ of evaluative research. However, whilst randomisation will ensure comparable groups, trials are still vulnerable to a range of biases that can undermine their internal validity. In this paper we describe a number of common threats to the internal validity of RCTs and methods of countering them. We highlight a number of examples from randomised trials in education and health care where problems of execution and analysis of the RCT has undermined their internal validity. However, awareness of these potential biases can lead to careful planning to avoid or reduce their occurrence. If good quality randomised trials are to inform policy and practice in education then rigorous trials need to be designed that are the least susceptible to threats to their validity.

In the dark The reporting of blinding status in randomized controlled trials

To determine the quality of reporting of blinding in randomized controlled trials (RCTs), we evaluated 40 consecutive RCTs published in each of five leading journals. We noted whether authors reported the blinding status of participants, health care providers, data collectors, judicial assessors of outcomes, data analysts, and manuscript writers. Explicit reporting of blinding status occurred in <25% of RCTs for all groups. Eighty-three RCTs, reported as double-blind, provided eight combinations of blinded groups. In conclusion, prestigious journals do not currently report blinding status optimally. To do so, journals should abandon the term “double blind” and explicitly report the blinding status of the groups involved in RCTs. Until such reporting occurs, clinicians will be left with uncertainty about the validity of RCTs that guide their clinical practice.