Acting on evidence can can only be done within the context of decision analysis
Dear Sir,
In their, otherwise, excellent article "When to act on evidence", Sheldon at al. failed to address the critical issue identified by EBM practitioners: how efficacious should a treatment be before it is worth administering. "Is NNT (the number of patients who need to be treated to achieve one favorable outcome )15 a large or a small number of patients that need to be treated to prevent one bad outcome?" (EBM 1996;1:37-38). Intertwined with this question is the question of specific integration of benefits and harms into practical decision, the issue which, so far, has not been successfully tackled within EBM movements.
We recently provided the answer to these questions by showing that action about given evidence can be only determined by linking evidence-based medicine (EBM) summary measures to decision analysis (DA) (Cancer Control, in press). By linking EBM to DA we showed that therapeutic benefits and harms are consequences (also referred to as utilities in DA terminology) of our treatment choices. This lack of understanding that EBM treatment indexes are in fact utilities is the main reason why alone they cannot be used in clinical decision making. The magnitude of benefits and harms associated with any single outcome is not necessarily related to the optimal treatment decision. The tenets of DA hold that we should choose a management strategy whose worth or expected value is maximal and not the one associated with highest utility of any particular outcome. By linking EBM to DA, we, for example, showed that in a prophylactic setting the treatment should be given only if NNT Benjamin Djulbegovic
University of Louisville
Department of Medicine
Division of Medical Oncology/Hematology
James Graham Brown Cancer Center
529 S. Jackson St.
Louisville, KY, USA 40202
Iztok Hozo
Indiana University Northwest
Department of Mathematics
3400 Broadway
Gary, IN, 46408
USA
Rapid Response:
Acting on evidence can can only be done within the context of decision analysis
Dear Sir,
In their, otherwise, excellent article "When to act on evidence", Sheldon at al. failed to address the critical issue identified by EBM practitioners: how efficacious should a treatment be before it is worth administering. "Is NNT (the number of patients who need to be treated to achieve one favorable outcome )15 a large or a small number of patients that need to be treated to prevent one bad outcome?" (EBM 1996;1:37-38). Intertwined with this question is the question of specific integration of benefits and harms into practical decision, the issue which, so far, has not been successfully tackled within EBM movements.
We recently provided the answer to these questions by showing that action about given evidence can be only determined by linking evidence-based medicine (EBM) summary measures to decision analysis (DA) (Cancer Control, in press). By linking EBM to DA we showed that therapeutic benefits and harms are consequences (also referred to as utilities in DA terminology) of our treatment choices. This lack of understanding that EBM treatment indexes are in fact utilities is the main reason why alone they cannot be used in clinical decision making. The magnitude of benefits and harms associated with any single outcome is not necessarily related to the optimal treatment decision. The tenets of DA hold that we should choose a management strategy whose worth or expected value is maximal and not the one associated with highest utility of any particular outcome. By linking EBM to DA, we, for example, showed that in a prophylactic setting the treatment should be given only if NNT Benjamin Djulbegovic
University of Louisville
Department of Medicine
Division of Medical Oncology/Hematology
James Graham Brown Cancer Center
529 S. Jackson St.
Louisville, KY, USA 40202
Iztok Hozo
Indiana University Northwest
Department of Mathematics
3400 Broadway
Gary, IN, 46408
USA
Competing interests: No competing interests