Progress in clinical neurosciences: measuring the benefit of therapies for neurological disorders

Clinicians in the neurosciences need to interpret and apply a growing body of evidence about therapy.

Using a clinical scenario about painful diabetic neuropathy and evidence about one treatment option, we review the advantages, limitations, and the clinical interpretation of commonly reported measures of effectiveness, emphasizing their application to the care of individual patients.

Absolute differences between treatment and control groups (e.g., absolute risk difference) are clinically intuitive and preferable to relative measures (e.g., relative risk). The number needed to treat is particularly useful and clinically applicable. Continuous measures are best interpreted using thresholds of clinically important change, which provide information about the number of patients experiencing meaningful improvement or worsening.

Using simple principles of evidence based care, clinicians can correctly interpret the common measures of treatment effectiveness and apply them to the care of individual patients.