ABSTRACT
Ensaios clínicos randomizados (ECR) são o padrão ouro para desenho experimental de estudo ou ensaio clínico. Apenas por meio de uma investigação do tipo ECR é possível avaliar e demonstrar a relação de causa-e-efeito entre um conjunto de variáveis independentes e dependentes. O ECR adicionou vantagens em relação aos outros modelos experimentais, principalmente devido à presença de um grupo controle. Existem várias críticas à validade interna das pesquisas em saúde, incluindo preconceitos e desvantagens que são apontadas para seu descrédito. OBJETIVO: O objetivo do presente estudo é informar características, vantagens, desvantagens e desvios deste método científico. MATERIAL E MÉTODOS: Análise crítica de método científico com base em revisão narrativa da literatura. Foi consultada a base de dados Medline por meio dos portais PubMed e Scopus, sem data de início e até julho de 2020, para extração das informações relativas aos ECR. Apenas artigos de língua inglesa foram incluídos, usando as palavras-chave "estudo randomizado controlado", "ensaio clínico randomizado", "projeto experimental" e "estudo experimental", intercaladas pelos operadores booleanos "AND ," "OR" e "NOT". Anais de conferências e resumos não foram considerados para a análise dos dados. RESULTADOS: Dos ECR selecionados, foram extraídas características, vantagens, desvantagens, importância e vantagens dos controles em pesquisa, o princípio de equilíbrio, ensaios clínicos randomizados na população pediátrica, ECR na população geriátrica, ameaças à validade interna e medidas para minimização de viéses e preconceitos em ECR. CONCLUSÃO: Tópicos relevantes dos ECR foram explicados nesta revisão que devem guiar pesquisadores clínicos.
Randomized controlled trial (RCT) is the gold standard of experimental design or clinical trial design. Only by RCT in research, the cause-and-effect relationship between a set of independent and dependent variables could be demonstrated. RCT has added advantages over other experimental designs due to the presence of the control group. The importance of control in health research trials and its advantages to be elaborated. Though various threats to internal validity in health research trials could be minimized by RCT, various biases in RCT and disadvantages add to its discredit. OBJECTIVE: The aim of the present narrative review is to brief the characteristics, advantages, disadvantages, and various biases in RCT. METHODS: This review does not follow the PRISMA statement, as it was a narrative review. Two databases, namely, Medline through PubMed and Scopus, were searched from inception to July 2020 for the information pertaining to RCTs and included in this narrative review. Only English language articles were searched with the keywords, "Randomized controlled trial," "Randomized clinical trial," "experimental design," and "experimental study." These keywords are linked together by the Boolean words, "AND," "OR" and "NOT." Conference proceedings and only abstracts were not considered for the review. RESULTS: RCTs were explained under characteristics, advantages, disadvantages, importance, and advantages of controls in research, the principle of equipoise, RCTs in the pediatric population, RCTs in the geriatric population, threats to internal validity and steps to minimize them and various biases in RCTs. CONCLUSION: The narrative presentation of RCTs under various important topics have been explained in this review.
Subject(s)
Randomized Controlled Trial , Research Design , Random AllocationABSTRACT
RESUMEN Fundamento: Los estudios de causalidad deben aportar resultados certeros, lo cual depende de la adecuación de los mismos, de ahí la necesidad de conocer los métodos que aseguren la validez de estas investigaciones. Objetivo: Sistematizar los métodos actuales para el estudio de causalidad en Medicina que incluye el diseño, los requerimientos que aseguran su validez y los métodos para el cumplimiento de estos requerimientos. Desarrollo: Se realizó una revisión bibliográfica en bases de datos biomédicas, se seleccionó la literatura de mayor actualidad, integralidad y cientificidad con la cual se organizó una síntesis crítica, a la que se le agregó la experiencia de las autoras. Se presentan técnicas para la detección y tratamiento de la confusión y la interacción y para garantizar la comparabilidad entre grupos. Entre las técnicas se destacan la aleatorización mendeliana, el puntaje de susceptibilidad, los G-métodos, los modelos estructurales marginales y anidados, la lógica difusa y el análisis estadístico implicativo. Conclusiones: A pesar del avance en los métodos estadísticos es el investigador el encargado de garantizar la no confusión residual y discernir entre lo estadísticamente significativo y lo clínicamente aceptable.
ABSTRACT Background: Causality studies must provide accurate results, which depends on their adequacy, therefore the need of knowing the methods that ensure the validity of these investigations. Objective: To systematize the current methods for the study of causality in Medicine that includes the design, the requirements that ensure its validity and the methods for complying with these requirements. Development: It was carried out a bibliographic review in biomedical databases and selected the most current, comprehensive, scientific literature, with this, a critical synthesis was organized, with the experience of the authors. Techniques for the detection and treatment of confusion and interaction were presented, also to ensure comparability between groups. Among the techniques, Mendelian randomization, susceptibility score, G-methods, marginal and nested structural models, fuzzy logic and implicative statistical analysis stand out. Conclusions: Despite the progress in statistical methods, the researcher is responsible for guaranteeing residual non-confusion and distinguishing between statistically significant and clinically acceptable.
Subject(s)
Reproducibility of Results , Data Interpretation, Statistical , Biomedical Research/statistics & numerical data , Case-Control Studies , Regression Analysis , Models, StructuralABSTRACT
Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.
ABSTRACT
Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.
ABSTRACT
Nearly all scientific studies explore causality,which will be met by directed acyclic graphs (DAGs).This paper systematically introduces graphic language,basic and interference rules of DAGs,and their applications into identifying research questions,understanding and undertaking research designs,guiding data analysis,classifying biases,etc.DAGs play key roles in causality studies.
ABSTRACT
Nearly all scientific studies explore causality,which will be met by directed acyclic graphs (DAGs).This paper systematically introduces graphic language,basic and interference rules of DAGs,and their applications into identifying research questions,understanding and undertaking research designs,guiding data analysis,classifying biases,etc.DAGs play key roles in causality studies.
ABSTRACT
RESUMO Os diferentes delineamentos de pesquisa apresentam diversas vantagens e limitações, inerentes às suas características principais. O conhecimento sobre o emprego adequado de cada um deles é de grande importância na aplicabilidade da epidemiologia clínica. Em terapia intensiva, uma classificação hierárquica dos delineamentos, sem compreender suas peculiaridades neste contexto, pode muitas vezes ser errônea, devendo-se atentar para problemas corriqueiros em ensaios clínicos randomizados e em revisões sistemáticas/metanálises, que abordem questões clínicas referentes a cuidados de pacientes gravemente enfermos.
ABSTRACT Different research designs have various advantages and limitations inherent to their main characteristics. Knowledge of the proper use of each design is of great importance to understanding the applicability of research findings to clinical epidemiology. In intensive care, a hierarchical classification of designs can often be misleading if the characteristics of the design in this context are not understood. One must therefore be alert to common problems in randomized clinical trials and systematic reviews/meta-analyses that address clinical issues related to the care of the critically ill patient.
Subject(s)
Humans , Research Design , Critical Illness/therapy , Critical Care/methods , Randomized Controlled Trials as Topic/methods , Intensive Care UnitsABSTRACT
ResumenLos diseños de investigación clínica, cuyo propósito es responder preguntas sobre causalidad, se pueden clasificar en relación con cuatro ejes: el número de grupos de estudio, la aplicación de una maniobra experimental, la direccionalidad causa-efecto y la fuente de la que se recaban los datos. Los diseños básicos más utilizados en epidemiología son el ensayo clínico, el estudio de cohortes, el estudio de casos y controles y la encuesta transversal. Este texto pretende facilitar la identificación y comprensión de cada uno de estos diseños mediante ejemplos relacionados con la asociación entre la vacunación con rotavirus y la invaginación intestinal.
AbstractDesign of clinical research whose purpose is to answer questions about causality can be classified in relation to four axes: the number of study groups, the implementation of an experimental maneuver, cause-effect directionality and source from which the data are collected. The basic designs used in epidemiology are the clinical trial, the cohort study, the case-control study and the cross-sectional survey. This text aims to facilitate the identification and understanding of each of these designs through examples related to the association between rotavirus vaccination and intussusception.
ABSTRACT
FUNDAMENTOS A produção científica da dermatologia brasileira, quantitativa e qualitativamente, é pouco conhecida e pouco estudada. OBJETIVO Analisar características da produção científica da dermatologia brasileira segundo o publicado nos Anais Brasileiros de Dermatologia entre 2003 e 2007. MÉTODOS Realizou-se estudo transversal através análise dos artigos publicados nas seções de investigação clínica, epidemiológica, laboratorial e terapêutica; caso clínico e comunicação dos Anais Brasileiros de Dermatologia entre 2003 e 2007. As variáveis de interesse foram: objeto temático, delineamento utilizado e grupo de enfermidades nas seções de investigação e caso clínico e o enfoque quanto à seção comunicação. RESULTADOS Entre os artigos de investigação predominaram os trabalhos clínicos (60,3%); os com temática cirúrgica ou cosmiátrica somaram 13%. Delineamento descritivo/observacional prevaleceu (81,9%), sendo a série decasos o mais utilizado (50%). Predominaram enfermidades infecciosas (33,6%) entre os de investigação e inflamatórias (28,6%) entre os casos relatados. Relato de casos (54,3%) foi o principal enfoque dado às comunicações. CONCLUSÃO Predominou a tradição descritiva nos artigos publicados no período. Delineamentos mais elaborados e sofisticados foram incomuns. O método científico e a análise crítica da literatura devem fazer parte do currículo da pós-graduação em dermatologia, stricto e lato sensu.
BACKGROUND - The scientific production of dermatology is not very known and studied in quantitative and qualitative aspects in Brazil. OBJECTIVE - To study the characteristics of the Brazilian scientific production published on the Anais Brasileiros de Dermatologia from 2003 to 2007. METHODS - A transversal study of articles published on the clinical, epidemiological, laboratory and therapeutic investigation; case report and communication sections of the Anais Brasileiros de Dermatologia, from 2003 to 2007, were reviewed. The variables studied were: the dermatological subspecialty focused; methodological analysis used; diseases or disorders investigated and the understanding of authors related to the communication section. RESULTS - Among investigational manuscripts, clinical studies prevailed (60.3%), those with surgical or cosmetic interest accounted for 13%. Descriptive and observational studies were the most common (81.9%), particularly the case series (50%). Infectious (33.6%) and inflammatory disease (28.6%) was the subject of investigation or case report, respectively. Case report was the most common subject on the communication section. CONLUSION - Descriptive methods were predominant among the research articles published in the studied period.More sophisticated and elaborated methods were uncommon. Research designs and critical analysis of the scientific literature must be part of the curriculum of the graduate and residency programs in dermatology.