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"Flogging dead horses": evaluating when have clinical trials achieved sufficiency and stability? A case study in cardiac rehabilitation

"Flogging dead horses": evaluating when have clinical trials achieved sufficiency and stability? A case study in cardiac rehabilitation
"Flogging dead horses": evaluating when have clinical trials achieved sufficiency and stability? A case study in cardiac rehabilitation
Background: Most systematic reviews conclude that another clinical trial is needed. Measures of sufficiency and stability may indicate whether this is true.

Objectives: To show how evidence accumulated on centre-based versus home-based cardiac rehabilitation, including estimates of sufficiency and stability

Methods: Systematic reviews of clinical trials of home versus centre-based cardiac rehabilitation were used to develop a cumulative meta-analysis over time. We calculated the standardised mean difference (SMD) in effect, confidence intervals and indicators of sufficiency and stability. Sufficiency refers to whether the meta-analytic database adequately demonstrates that an intervention works - is statistically superior to another. It does this by assessing the number of studies with null results that would be required to make the meta-analytic effect non-statistically significant. Stability refers to whether the direction and size of the effect is stable as new studies are added to the meta-analysis.

Results: The standardised mean effect difference reduced over fourteen comparisons from a non-significant difference favouring home-based cardiac rehabilitation to a very small difference favouring hospital (SMD -0.10, 95% CI -0.32 to 0.13). This difference did not reach the sufficiency threshold (failsafe ratio 0.039 < 1) but did achieve the criteria for stability (cumulative slope 0.003 < 0.005).

Conclusions: The evidence points to a relatively small effect difference which was stable but not sufficient in terms of the suggested thresholds. Sufficiency should arguably be based on substantive significance and decided by patients. Research on patient preferences should be the priority. Sufficiency and stability measures are useful tools that need to be tested in further case studies.
1745-6215
83
Dent, Louise
f10597da-079e-4140-8600-eb3f91f7227c
Taylor, Rod
12fb1379-fab8-4713-9c5d-2662b5b6ca14
Jolly, Kate
cc422201-8368-47fd-9ef9-cc844cfc0d8d
Raftery, James
27c2661d-6c4f-448a-bf36-9a89ec72bd6b
Dent, Louise
f10597da-079e-4140-8600-eb3f91f7227c
Taylor, Rod
12fb1379-fab8-4713-9c5d-2662b5b6ca14
Jolly, Kate
cc422201-8368-47fd-9ef9-cc844cfc0d8d
Raftery, James
27c2661d-6c4f-448a-bf36-9a89ec72bd6b

Dent, Louise, Taylor, Rod, Jolly, Kate and Raftery, James (2011) "Flogging dead horses": evaluating when have clinical trials achieved sufficiency and stability? A case study in cardiac rehabilitation. Trials, 12, 83. (doi:10.1186/1745-6215-12-83). (PMID:21418648)

Record type: Article

Abstract

Background: Most systematic reviews conclude that another clinical trial is needed. Measures of sufficiency and stability may indicate whether this is true.

Objectives: To show how evidence accumulated on centre-based versus home-based cardiac rehabilitation, including estimates of sufficiency and stability

Methods: Systematic reviews of clinical trials of home versus centre-based cardiac rehabilitation were used to develop a cumulative meta-analysis over time. We calculated the standardised mean difference (SMD) in effect, confidence intervals and indicators of sufficiency and stability. Sufficiency refers to whether the meta-analytic database adequately demonstrates that an intervention works - is statistically superior to another. It does this by assessing the number of studies with null results that would be required to make the meta-analytic effect non-statistically significant. Stability refers to whether the direction and size of the effect is stable as new studies are added to the meta-analysis.

Results: The standardised mean effect difference reduced over fourteen comparisons from a non-significant difference favouring home-based cardiac rehabilitation to a very small difference favouring hospital (SMD -0.10, 95% CI -0.32 to 0.13). This difference did not reach the sufficiency threshold (failsafe ratio 0.039 < 1) but did achieve the criteria for stability (cumulative slope 0.003 < 0.005).

Conclusions: The evidence points to a relatively small effect difference which was stable but not sufficient in terms of the suggested thresholds. Sufficiency should arguably be based on substantive significance and decided by patients. Research on patient preferences should be the priority. Sufficiency and stability measures are useful tools that need to be tested in further case studies.

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More information

e-pub ahead of print date: 21 March 2011
Published date: March 2011
Organisations: Faculty of Medicine, Clinical Trials Unit

Identifiers

Local EPrints ID: 354816
URI: http://eprints.soton.ac.uk/id/eprint/354816
ISSN: 1745-6215
PURE UUID: 066ad6d3-e8e6-4a12-bc1f-5dd513a2eecd

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Date deposited: 23 Jul 2013 09:12
Last modified: 06 Oct 2020 23:26

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