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Consistently estimating risk difference in a jurisdiction of interest: odds solution to relative risk fallacies

Conference Paper


Abstract


  • Economic analyses in health technology assessment

    often require estimation of absolute risk difference (ARD)

    for outcomes such as survival or progression, given base risk in

    the jurisdiction of interest and trial evidence of treatment effects.

    We demonstrate that odds ratios (OR) provide distinct advantages

    over relative risk (RR) in consistently estimating such ARD

    independent of the framing of effects (e.g. mortality or survival)

    for direct and indirect comparisons. METHODS: Use of RR is

    shown to lead to inferential anomalies in estimating ARD, while

    consistently estimated using OR. These inferential anomalies and

    odds solution are illustrated for indirect comparison of Natiluzimab

    versus Interferon beta-1b for multiple sclerosis, as well as

    direct comparisons. RESULTS: Standard use of relative risk to

    calculate ARD in indirect comparison suggests Natiluzimab is

    more effective than Interferon for progression (RR = 0.70, ARD

    = 21% for a base risk of 70% progression) but less effective than

    Interferon for no progression (RR = 0.84, ARD = 4.8%). This inferential anomaly is avoided using OR, with odds of progression

    (0.83) the reciprocal of that for no progression (1.21), and

    ARD of 4.1% in favor of Nataluzimab with progression or no

    progression. For direct comparisons ARD is shown to be consistently

    estimated with OR but change with framing of effects

    using RR wherever epidemiological risk differs from trial risk in

    the comparator arm. CONCLUSIONS: Odds ratios allow consistent

    estimation of absolute risk differences regardless of

    framing of effects in direct and indirect comparisons. This overcomes

    inferential anomalies that arise with use of relative risk in

    such comparisons whenever base risk differs in the jurisdiction of

    interest from that in trials, or base risk in the common arms

    differs in indirect comparisons. Consequently, odds ratios avoid

    selection biases in framing of effects inherent with risk ratios and

    are suggested as the preferred metric in estimating such risk

    differences.

Authors


  •   Eckermann, Simon
  •   Coory, Michael (external author)
  •   Willan, Andrew R. (external author)

Publication Date


  • 2008

Citation


  • S. Eckermann, M. Coory & A. R. Willan, "Consistently estimating risk difference in a jurisdiction of interest: odds solution to relative risk fallacies", ISPOR 11th Annual European Congress. Wiley-Blackwell Publishing, (2008) A577-A578.

Scopus Eid


  • 2-s2.0-60549116877

Ro Metadata Url


  • http://ro.uow.edu.au/ahsri/177

Start Page


  • A577

End Page


  • A578

Abstract


  • Economic analyses in health technology assessment

    often require estimation of absolute risk difference (ARD)

    for outcomes such as survival or progression, given base risk in

    the jurisdiction of interest and trial evidence of treatment effects.

    We demonstrate that odds ratios (OR) provide distinct advantages

    over relative risk (RR) in consistently estimating such ARD

    independent of the framing of effects (e.g. mortality or survival)

    for direct and indirect comparisons. METHODS: Use of RR is

    shown to lead to inferential anomalies in estimating ARD, while

    consistently estimated using OR. These inferential anomalies and

    odds solution are illustrated for indirect comparison of Natiluzimab

    versus Interferon beta-1b for multiple sclerosis, as well as

    direct comparisons. RESULTS: Standard use of relative risk to

    calculate ARD in indirect comparison suggests Natiluzimab is

    more effective than Interferon for progression (RR = 0.70, ARD

    = 21% for a base risk of 70% progression) but less effective than

    Interferon for no progression (RR = 0.84, ARD = 4.8%). This inferential anomaly is avoided using OR, with odds of progression

    (0.83) the reciprocal of that for no progression (1.21), and

    ARD of 4.1% in favor of Nataluzimab with progression or no

    progression. For direct comparisons ARD is shown to be consistently

    estimated with OR but change with framing of effects

    using RR wherever epidemiological risk differs from trial risk in

    the comparator arm. CONCLUSIONS: Odds ratios allow consistent

    estimation of absolute risk differences regardless of

    framing of effects in direct and indirect comparisons. This overcomes

    inferential anomalies that arise with use of relative risk in

    such comparisons whenever base risk differs in the jurisdiction of

    interest from that in trials, or base risk in the common arms

    differs in indirect comparisons. Consequently, odds ratios avoid

    selection biases in framing of effects inherent with risk ratios and

    are suggested as the preferred metric in estimating such risk

    differences.

Authors


  •   Eckermann, Simon
  •   Coory, Michael (external author)
  •   Willan, Andrew R. (external author)

Publication Date


  • 2008

Citation


  • S. Eckermann, M. Coory & A. R. Willan, "Consistently estimating risk difference in a jurisdiction of interest: odds solution to relative risk fallacies", ISPOR 11th Annual European Congress. Wiley-Blackwell Publishing, (2008) A577-A578.

Scopus Eid


  • 2-s2.0-60549116877

Ro Metadata Url


  • http://ro.uow.edu.au/ahsri/177

Start Page


  • A577

End Page


  • A578