Bias in published cost effectiveness studies: systematic review

doi:10.1136/bmj.38737.607558.80

BMJ 2006;332:699-703 (25 March), doi:10.1136/bmj.38737.607558.80 (published 22 February 2006)

Research

Bias in published cost effectiveness studies: systematic review

Chaim M Bell, assistant professor of medicine and health, policy, management, and evaluation¹, David R Urbach, assistant professor of medicine and health, policy, management, and evaluation², Joel G Ray, assistant professor of medicine and health, policy, management, and evaluation¹, Ahmed Bayoumi, assistant professor of medicine and health, policy, management, and evaluation¹, Allison B Rosen, assistant professor of medicine³, Dan Greenberg, senior lecturer⁴, Peter J Neumann, director⁵

¹ St Michael's Hospital, Toronto, Ontario, Canada M5B 1W8, ² University Health Network, Toronto, ³ University of Michigan, Ann Arbor, MI, USA, ⁴ Health Systems Management, Ben-Gurion University of the Negev, Beersheba, Israel, ⁵ Center for the Evaluation of Value and Risk in Health, Institute for Clinical Research and Health Policy Studies, Tufts University School of Medicine, Boston, USA

Correspondence to: C M Bell, St Michael's Hospital, Toronto, Ontario, Canada M5B 1W8 bellc{at}smh.toronto.on.ca

Abstract

Objective To investigate if published studies tend to reportfavourable cost effectiveness ratios (below $20 000, $50 000,and $100 000 per quality adjusted life year (QALY) gained) andevaluate study characteristics associated with this phenomenon.

Design Systematic review.

Studies reviewed 494 English language studies measuring healtheffects in QALYs published up to December 2001 identified usingMedline, HealthSTAR, CancerLit, Current Content, and EconLitdatabases.

Main outcome measures Incremental cost effectiveness ratiosmeasured in dollars set to the year of publication.

Results Approximately half the reported incremental cost effectivenessratios (712 of 1433) were below $20 000/QALY. Studies fundedby industry were more likely to report cost effectiveness ratiosbelow $20 000/QALY (adjusted odds ratio 2.1, 95% confidenceinterval 1.3 to 3.3), $50 000/QALY (3.2, 1.8 to 5.7), and $100000/QALY (3.3, 1.6 to 6.8). Studies of higher methodologicalquality (adjusted odds ratio 0.58, 0.37 to 0.91) and those conductedin Europe (0.59, 0.33 to 1.1) and the United States (0.44, 0.26to 0.76) rather than elsewhere were less likely to report ratiosbelow $20 000/QALY.

Conclusion Most published analyses report favourable incrementalcost effectiveness ratios. Studies funded by industry were morelikely to report ratios below the three thresholds. Studiesof higher methodological quality and those conducted in Europeand the US rather than elsewhere were less likely to reportratios below $20 000/QALY.

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Cost effectiveness studies show publication bias
BMJ 2006 332: 0. [Full Text]

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