Abstrakt
The results of many research findings have come under scrutiny in recent years due to the introduction of systematic errors at one stage or the other of the research. Over the years, literature has been rife about the issue of bias with many authors describing unique types of bias. More often, researchers have often been left in the dark about the basic concept of this important phenomenon. Using a method of cross referencing, exploded tree search, consultation of textbooks of epidemiology and conference proceedings, this article examines the basic concept of bias and the current understanding of bias as present in various literature. A simple classification of biases into conceptualization, selection and information biases is proposed. A distinction is made of confounding as describing an association that is true but potentially misleading and bias which on the other hand creates an association that is not true. The article further goes on to describe the different types of biases applicable to different study designs before concluding on the need for researchers to pay attention to the issue of bias so as to make their studies useful to readers.
Keywords: Researchers, bias, epidemiology, concepualization, confounding
Résumé
Les résultats des données de plusieurs recherches ont été contrôlés ces années du a l’introduction des erreurs systématiques dans une des étapes de la recherché. Durant des années la littérature a été détournée a propos du problème de biais et plusieurs auteurs décrivant les types de biais. Le plus souvent Les chercheurs sont restes dans l’obscurité par rapport aux concepts de base de ce phénomène important. En utilisant la méthode de référence croisée, la recherché embranchée, la consultation des livres d’épidémiologie et les rapports des conférences; cette article examine le concept de base du biais et la compréhension récente du biais dans différente littérature. Une simple classification des biais en: biais de conceptualisation, de sélection et d’information est proposée. La distinction a été faite sur la complexité en décrivant une association vraie mais potentiellement mal dirigée et biais qui d’un cote crée une association fausse. Cet article décrit l’applicabilité des différent types de biais a différent types de dessin de recherché avant de conclure sur la nécessité des chercheurs de prendre d’attention sur le problème de biais afin de faire leurs études important aux lecteurs.
Correspondence: Dr. A.O. Adebiyi, Clinical Epidemiology Unit, Department of Community Medicine, University College Hospital, Ibadan, Nigeria.
Bibliografia
Ioannidis JPA. Why most published research findings are false. Plos Med 2005; 2(8): e124 DOI: 10. 1371/journal.pmed.0020124
Sackett DL. Bias in analytic research. J Chron Dis 1979; 32: 51-63.
Delgado-Rodriguez M and Llorca J. Bias. J Epidemiol Community Health 2004; 58:635-641. Accessed from www.jech.com on 21/2/2007
Rothman KJ. Epidemiology. Oxford University Press, Inc, New York, 2002.
Vineis P and McMichael AJ. Bias and confounding in molecular epidemiological studies: special considerations. Carcinogenesis 1998; 19(12):2063-2067.
Last JM. A dictionary of epidemiology. 3rd Ed. New York: Oxford University Press, 1995.
Pollock AV and Evans M. Bias and fraud in medical research: a review. Journal of the Royal Society of Medicine 1985; 78: 937-939(Pollock and Evans)
Epidemiology of occupational health. Karvonen M and Mikheev (Eds). World Health Organization Regional Office for Europe, Copenhagen, 1986.
Woolf SH, Rothemich SF, Johnson RE and Marsland DW. Selection bias from requiring patients to give consent to examine data for health services research. Arch Fam Med. 2000;9: 1111-1118
Al-Shahi R and Vousden C, Warlow C and for the Scottish Intracranial Vascular Malformation Study (SIVMS) Steering Committee. Bias from requiring explicit consent from all participants in observational research: prospective, population based study. BMJ 2005, doi:10.1136/bmj.38624.397569.68
Grimes DA and Schultz KF. Bias and causal associations in observational research. Lancet 2002; 359: 248-252
Clinical Epidemiology. The Essentials. Fletcher RH and Fletcher SW. 4th edition. Lippincott Williams and Wilkins
Davey SG and Ebrahim S. Data dredging, bias, or confounding. BMJ 2002;325:1437-1438.
Morgenstern H. Ecologic Studies in Epidemiology: Concepts, Principles, and Methods. Annual Review of Public Health 1995; 16: 61-81.
Burke MA and Eichler MA. The BIAS FREE Framework: A practical tool for identifying and eliminating social biases in health research 2006
Burke MA, Peggs, Taylork, Mykituk R et al. The construction of disability oral risk in genetic counselling discourse. Toronto; Roeher Institute. 2003.
Ruiz-Cantero MT, Vives-Cases C, Artazcoz L, Delgado A, Calvente M, Miqueo C, Montero I, Ortiz R, Ronda E, Ruiz I and Valls C. A framework to analyse gender bias in epidemiological research. J. Epidemiol. Community Health 2007;61;ii46-ii53 doi:10.1136/jech.2007.062034.
Yerman T, Gan WQ and Sin DD. The influence of gender on the effects of aspirin in preventing myocardial infarction. BMC Medicine 2007, 5:29doi
Gandhi M, Aweeka F, Greenblatt RM and Blaschke TF. Sex differences in pharmacokinetics and pharmacodynamics. Annual Rev of Pharmtox 2004; 44: 499-523.
Decullier E, Lhéritier V and Chapuis F. Fate of biomedical research protocols and publication bias in France: retrospective cohort study. BMJ 2005; Doi:10.1136/bmj. 38488.385995.8F
Abramson JH. Making sense of data. New York: Oxford University Press, 1988.
Deeks JJ, Dinnes J, D’Amico R, et al. Evaluating non-randomized intervention studies. Health Technol Assess 2003; 7:1-173
Salas M, Hofman A and Strieker BHC. Confounding by indication: an example of variation in the use of epidemiologic terminology. Am J Epidemiol 1999; 149(11):981-983
de Vries F, van Staa TP, Bracke MSG, Cooper C, Leufkens HGM and Lammers JWJ. Severity of obstructive airway disease and risk of osteoporotic fracture. Eur Respir J 2005; 25: 879–884
Feenstra H, Grobbee RE, In’t Veld BA and Stricker BHC. Confounding by contraindication in a nationwide cohort study of risk for death in patients taking Ibopamine. Ann Intern Med. 2001;134:569-572.