LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Burton, Christopher (2012)
Publisher: Public Library of Science
Journal: PLoS ONE
Languages: English
Types: Article
Subjects: Agricultural and Biological Sciences(all), Applied Mathematics, Research Article, Mathematics, Clinical Research Design, Medicine, Health Care Policy, /dk/atira/pure/subjectarea/asjc/1100, Q, R, Biochemistry, Genetics and Molecular Biology(all), /dk/atira/pure/subjectarea/asjc/2700, /dk/atira/pure/subjectarea/asjc/1300, Science, Medicine(all), Statistics, Non-Clinical Medicine
Background

Systematic reviews of complex interventions commonly find heterogeneity of effect sizes among similar interventions which cannot be explained. Commentators have suggested that complex interventions should be viewed as interventions in complex systems. We hypothesised that if this is the case, the distribution of effect sizes from complex interventions should be heavy tailed, as in other complex systems. Thus, apparent heterogeneity may be a feature of the complex systems in which such interventions operate.

Methodology/Principal Findings

We specified three levels of complexity and identified systematic reviews which reported effect sizes of healthcare interventions at two of these levels (interventions to change professional practice and personal interventions to help smoking cessation). These were compared with each other and with simulated data representing the lowest level of complexity. Effect size data were rescaled across reviews at each level using log-normal parameters and pooled. Distributions were plotted and fitted against the inverse power law (Pareto) and stretched exponential (Weibull) distributions, heavy tailed distributions which are commonly reported in the literature, using maximum likelihood fitting. The dataset included 155 studies of interventions to change practice and 98 studies of helping smoking cessation. Both distributions showed a heavy tailed distribution which fitted best to the inverse power law for practice interventions (exponent = 3.9, loglikelihood = −35.3) and to the stretched exponential for smoking cessation (loglikelihood = −75.2). Bootstrap sensitivity analysis to adjust for possible publication bias against weak results did not diminish the goodness of fit.

Conclusions/Significance

The distribution of effect sizes from complex interventions includes heavy tails as typically seen in both theoretical and empirical complex systems. This is in keeping with the idea of complex interventions as interventions in complex systems.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • 1. Campbell M, Fitzpatrick R, Haines A, Kinmonth AL, Sandercock P, et al. (2000) Framework for design and evaluation of complex interventions to improve health. BMJ 321(7262): 694-696.
    • 2. Craig P, Dieppe P, Macintyre S, Michie S, Nazareth I, et al. (2008) Developing and evaluating complex interventions: the new Medical Research Council guidance. BMJ 337: a1655.
    • 3. Oxman AD, Thomson MA, Davis DA, Haynes RB (1995) No magic bullets: a systematic review of 102 trials of interventions to improve professional practice. CMAJ 153(10): 1423-1431.
    • 4. Coiera E (2011) Why system inertia makes health reform so difficult. BMJ 342.
    • 5. Rickles D, Hawe P, Shiell A (2007) A simple guide to chaos and complexity. J Epidemiol Community Health 61(11): 933-937.
    • 6. Rickles D (2009) Causality in complex interventions. Med Health Care Philos 12(1): 77-90.
    • 7. Hawe P, Shiell A, Riley T (2009) Theorising interventions as events in systems. Am J Community Psychol 43(3-4): 267-276.
    • 8. Shiell A, Hawe P, Gold L (2008) Complex interventions or complex systems? Implications for health economic evaluation. BMJ 336(7656): 1281-1283.
    • 9. Paley J (2010) The appropriation of complexity theory in health care. J Health Serv Res Policy 15(1): 59-61.
    • 10. Hammond RA (2009) Complex systems modeling for obesity research. Prev Chronic Dis 6(3).
    • 11. Rwashana AS, Williams DW, Neema S (2009) System dynamics approach to immunization healthcare issues in developing countries: a case study of Uganda. Health Informatics Journal 15(2): 95-107.
    • 12. Godin G, Kok G (1996) The theory of planned behavior: a review of its applications to health-related behaviors. Am J Health Promot 11(2): 87-98.
    • 13. Crabtree BF, Nutting PA, Miller WL, McDaniel RR, Stange KC, et al. (2011) Primary care practice transformation is hard work: insights from a 15-year developmental program of research. Med Care 49 Suppl: S28-S35.
    • 14. Miller WL, Crabtree BF, McDaniel R, Stange KC (1998) Understanding change in primary care practice using complexity theory. J Fam Pract 46(5): 369-376.
    • 15. Plsek PE, Greenhalgh T (2001) Complexity science: The challenge of complexity in health care. BMJ 323(7313): 625-628.
    • 16. Newman MEJ (2011) Complex Systems: A Survey. Am J Phys 79: 800-810.
    • 17. West BJ (2006) Where medicine went wrong: rediscovering the path to complexity. Singapore: World Scientific Publishing.
    • 18. Clauset A, Shalizi CR, Newman MEJ (2009) Power-law distributions in empirical data. SIAM Review 51: 661-703.
    • 19. Bak P (1996) How Nature Works: The Science of Self-Organised Criticality. London: Oxford University Press.
    • 20. Love T, Burton C (2005) General practice as a complex system: a novel analysis of consultation data. Fam Pract 22(3): 347-352.
    • 21. Jamtvedt G, Young JM, Kristoffersen DT, O'Brien MA, Oxman AD (2006) Audit and feedback: effects on professional practice and health care outcomes. Cochrane Database Syst Rev (2): CD000259.
    • 22. O'Brien MA, Rogers S, Jamtvedt G, Oxman AD, Odgaard-Jensen J, et al. (2007) Educational outreach visits: effects on professional practice and health care outcomes. Cochrane Database Syst Rev (4): CD000409.
    • 23. Forsetlund L, Bjorndal A, Rashidian A, Jamtvedt G, O'Brien MA, et al. (2009) Continuing education meetings and workshops: effects on professional practice and health care outcomes. Cochrane Database Syst Rev (2): CD003030.
    • 24. Silagy C, Lancaster T, Stead L, Mant D, Fowler G (2004) Nicotine replacement therapy for smoking cessation. Cochrane Database Syst Rev (3): CD000146.
    • 25. Lancaster T, Stead L (2004) Physician advice for smoking cessation. Cochrane Database Syst Rev (4): CD000165.
    • 26. Lancaster T, Stead LF (2005) Individual behavioural counselling for smoking cessation. Cochrane Database Syst Rev (2): CD001292.
    • 27. Lai DT, Cahill K, Qin Y, Tang JL (2010) Motivational interviewing for smoking cessation. Cochrane Database Syst Rev (1): CD006936.
    • 28. Egger M, Dickersin K, Davey Smith G (2001) Problems and limitations in conducting systematic reviews. In: Egger M, Davey Smith G, Altman D, eds. Systematic Reviews in Health Care: meta-analysis in context. London: BMJ Publishing. pp 43-68.
    • 29. Cochrane Effective Practice and Organisation of Care Group (2011) Tables and other information not published in our reviews. Available: http://epoc.cochrane. org/tables.
    • 30. Adamic L (2011) Complex systems: Unzipping Zipf's law. Nature 474(7350): 164-165.
    • 31. Baek S, Bernhardsson S, Minnhagen P (2011) Zipf's law unzipped. New Journal of Physics 13(4): 043004.
    • 32. Carlson JM, Doyle J (2002) Complexity and robustness. Proc Natl Acad Sci U S A 99 Suppl 1: 2538-2545.
  • No similar publications.

Share - Bookmark

Cite this article