Frequency of treatment-effect modification affecting indirect comparisons: A systematic review

Coory, Michael and Jordan, Susan (2010) Frequency of treatment-effect modification affecting indirect comparisons: A systematic review. PharmacoEconomics, 28 9: 723-732. doi:10.2165/11535670-000000000-00000


Author Coory, Michael
Jordan, Susan
Title Frequency of treatment-effect modification affecting indirect comparisons: A systematic review
Journal name PharmacoEconomics   Check publisher's open access policy
ISSN 1170-7690
1590-9158
1179-2027
Publication date 2010-09-01
Sub-type Critical review of research, literature review, critical commentary
DOI 10.2165/11535670-000000000-00000
Volume 28
Issue 9
Start page 723
End page 732
Total pages 10
Editor Christopher I. Carswell
Place of publication Auckland, N.Z.
Publisher Adis International
Collection year 2011
Language eng
Formatted abstract
A key assumption of indirect comparisons is similarity, which means that, in the face of differences in patient characteristics or study methods, there is no treatment-effect modification across sides of the indirect comparison. We therefore conducted a systematic review of MEDLINE and EMBASE from inception to November 2009 to summarize currently available information about how frequently, on average, treatment-effect modification occurs across trials that might be used on different sides of an indirect comparison.

Although similarity is a key assumption, there is currently no published evidence specifically for indirect comparisons about how frequently treatment-effect modification occurs.

Six analyses were identified that assessed treatment-effect modification across studies included in direct head-to-head meta-analyses. Such analyses are relevant to indirect comparisons because the phenomenon being investigated would occur with similar frequency. They provide important information because lack of treatment-effect modification across sides of an indirect comparison cannot be directly assessed statistically; this is in contrast to direct head-to-head meta-analyses where Cochrane's Q statistic or I2 can be used. For ratio measures such as the odds ratio and relative risk, treatment-effect modification occurred for 10–33% of meta-analyses. For the risk difference (an arithmetic measure), the range was 15–46%.

It is not prudent to assume similarity in an indirect comparison, based only on the result that ratio measures such as the odds ratio are reasonably robust to treatment-effect modification. All indirect comparisons should include a thorough narrative comparison of differences in patient characteristics and study methods. This will provide end users with the best evidence with which to make an assessment of the likelihood of treatment-effect modification and the plausibility of the similarity assumption.
© 2010 Adis Data Information BV. All rights reserved.
Keyword Clinical-trials
Competing interventions
Empirical-evidence
Metaanalysis
Heterogeneity
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Official 2011 Collection
School of Public Health Publications
 
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Created: Sun, 17 Oct 2010, 00:03:52 EST