Back to list

Observational studies: going beyond the boundaries of randomized controlled trials

Wenying Yang a, Alexey Zilov b, Pradana Soewondo c, Ole Molskov Bech d, Fawzia Sekkal e and Philip D. Home f *

Diabetes Research and Clinical Practice, Supplement 1, Volume 88, pages S3 - S9

Published online Dec-2010


Article view:

Abstract

The term observational study describes a wide range of study designs including prospective and retrospective cohort studies, case-control studies, and cross-sectional studies, a defining feature of which is that any intervention studied is determined by clinical practice and not the protocol. Data from large, prospective observational studies provide information about the safety and efficacy of medicines in daily clinical use. Such observational studies are generally carried out once a medicine has received approval from regulatory agencies. Observational trials have inherent limitations in terms of their susceptibility to bias and confounding, restricting their ability to define causality. However, their strengths include that they reflect daily clinical practice more closely than randomized controlled trials (RCTs), both in terms of the heterogeneous patient populations that are included, and the medical interventions that they receive. Therefore, observational trials can provide clinically relevant information that is not necessarily provided by RCTs. Given the limitations of an observational study approach, it is important to optimize their study design to maximize their validity, and thus, in particular, known causes of bias and confounding should be measured. Medical investigators, health authorities, and the pharmaceutical industry all have important roles to play in designing, approving, and performing observational studies.

Keywords: Type 2 diabetes, Observational study, Insulin.


Article Outline

References

  • 1 HC Sox, S Greenfield. Comparative effectiveness research: a report from the Institute of Medicine. Ann. Intern. Med.. 2009;151:203-205 Crossref.
  • 2 N Freemantle, T Strack. Real-world effectiveness of new medicines should be evaluated by appropriately designed clinical trials. J. Clin. Epidemiol.. 2009 Oct 30;10.1016/j.jclinepi 2009.07.013
  • 3 RJ Ligthelm, V Borzì, J Gumprecht, R Kawamori, Y Wenying, P Valensi. Importance of observational studies in clinical practice. Clin. Ther.. 2007;29:1284-1292 Crossref.
  • 4 CG Victora, JP Habicht, J Bryce. Evidence-based public health: moving beyond randomized trials. Am. J. Public Health.. 2004;94:400-405 Crossref.
  • 5 N Black. Why we need observational studies to evaluate the effectiveness of healthcare. BMJ.. 1996;312:1215-1218 Crossref.
  • 6 WB Kannel, DL McGee. Diabetes and cardiovascular risk factors: the Framingham study. Circulation. 1979;59:8-13 Crossref.
  • 7 I Tzoulaki, M Molokhia, V Curcin, MP Little, CJ Millett, A Ng, et al. Risk of cardiovascular disease and all cause mortality among patients with type 2 diabetes prescribed oral antidiabetes drugs: retrospective cohort study using UK general practice research database. BMJ. 2009;339:b4731 10.1136/bmj.b4731 Crossref.
  • 8 CJ Mann. Observational research methods. Research design II: cohort, cross sectional, and case-control studies. Emerg. Med. J.. 2003;20:54-60 Crossref.
  • 9 CJ Biesheuvel, Y Vergouwe, R Oudega, AW Hoes, DE Grobbee, KG Moons. Advantages of the nested case-control design in diagnostic research. BMC Med. Res. Methodol.. 2008;8:48 Crossref.
  • 10 JL Palmer, M Gibbs, HW Scheijbeler, RW Kotchie, S Nielsen, J White, WJ Valentine. Cost-effectiveness of switching to biphasic insulin aspart in poorly-controlled type 2 diabetes patients in China. Adv. Ther.. 2008;25:752-774 Crossref.
  • 11 AJ Palmer, S Roze, WJ Valentine, ME Minshall, V Foos, FM Lurati, M Lammert, GA Spinas. Validation of the CORE Diabetes Model against epidemiological and clinical studies. Curr. Med. Res. Opin.. 2004;20(Suppl 1):S27-S40
  • 12 WJ Valentine, G Goodall, M Aagren, S Nielsen, AJ Palmer, K Erny-Albrecht. Evaluating the cost-effectiveness of therapy conversion to insulin detemir in patients with type 2 diabetes in Germany: a modelling study of long-term clinical and cost outcomes. Adv. Ther.. 2008;25:567-584 Crossref.
  • 13 WJ Valentine, AJ Palmer, M Lammert, L Nicklasson, V Foos, S Roze. Long-term clinical and cost outcomes of treatment with biphasic insulin aspart 30/70 versus insulin glargine in insulin naïve type 2 diabetes patients: cost-effectiveness analysis in the UK setting. Curr. Med. Res. Opin.. 2005;21:2063-2071 Crossref.
  • 14 HM Krumholz. Outcomes research: generating evidence for best practice and policies. Circulation. 2008;118:309-318 Crossref.
  • 15 JP Vandenbroucke, E von Elm, DG Altman, PC Gøtzsche, CD Mulrow, SJ Pocock, et al., STROBE initiative. Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration. Ann. Intern. Med.. 2007;147:W163-W194
  • 16 BD Furberg, CD Furberg. What are the weaknesses of randomized controlled clinical trials?. BD Furberg, CD Furberg (Eds.) Evaluating clinical research. All that glitters is not gold (Springer, New York, 2007) 17-22 Crossref.
  • 17 Declaration of Helsinki. 2008. Accessed at: http://www.wma.net/en/30publications/10policies/b3/index.html on December 23rd 2009.
  • 18 International Conference On Harmonisation (ICH). Harmonised Tripartite Guideline For Good Clinical Practice E6 (R1). Accessed at: http://www.ich.org/LOB/media/MEDIA482.pdf (1996) on December 23rd 2009
  • 19 J Orchard. For debate: Should observational clinical studies require ethics committee approval?. J. Sci. Med Sport. 2008;11:239-242 Crossref.
  • 20 B Moser. Letter to the editor. Should observational clinical studies require ethics committee approval?. J. Sci. Med. Sport. 2008;11:518 Crossref.
  • 21 E von Elm, DG Altman, M Egger, SJ Pocock, PC Gøtzsche, JP Vandenbroucke, STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. J. Clin. Epidemiol.. 2008;61:344-349 Crossref.

Footnotes

a Department of Endocrinology, China-Japan Friendship Hospital, Beijing, China

b Department of Endocrinology, IM Sechenov Moscow Medical Academy, Moscow, Russia

c Division of Endocrinology, Department of Internal Medicine, Faculty of Medicine, University of Indonesia, Cipto Mangunkusumo Hospital, Jakarta, Indonesia

d Novo Nordisk Region International Operations A/S, Zurich, Switzerland

e Bad El Oued Hospital, Algiers, Algeria

f Newcastle University, Newcastle upon Tyne, UK

* Correspondence to: Professor P.D. Home, ICM-Diabetes, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK

Back to list