Faculty of Health and Medical Sciences

Apply the evidence

Do the results apply to your patient?

Applying the results to your patient incorporates:

  • some assessment of their individual baseline risk
  • judgement about whether the evidence can be extrapolated to your patient
  • understanding of factors that may increase the benefits or harms they experience

Click on each of the tabs below to review key aspects of applicability.

Baseline risks

  • For prevention studies, does your patient have the same baseline risk as study participants?
  • For diagnosis and clinical findings studies, you can estimate the pre-test probability for your patient in order to calculate a positive and negative predictive value of the test.
    • Online risk predictors are available for some common conditions, such as cardiovascular risk and breast cancer. These tools may help you determine baseline risk in complex, multifactorial conditions.
    • Calculate your patient’s NNT using your patient’s expected event rate if they received the control treatment (PEER).
    • NNT (your patient) = 1/(PEER x RRR).
  • Estimate the burden of disease for this person if you do nothing.
    • Sometimes doing nothing is the best approach for an individual.

Differences from trial patients

  • Check whether your patient would have been eligible for the study, and how they may be similar or different to the study population.
  • Your patient may have been excluded due to their age, co-morbidities, or other medications. You may need to consider whether these factors would make a study treatment less effective or cause more side effects.
    • Appraise important aspects in which your patient is not similar. Are they so different that the study results won’t apply to them?
    • Consider whether your patient is taking medications which could interact with the study treatment.
    • Gauge whether your patient is likely to comply with the treatment dosage and duration. Determine whether ethnicity affects disease or response to treatment.


  • Consider any patient factors that may make toxicity more likely.
    • Older patients may have poor organ function, early dementia, compliance issues, or be socially isolated.
    • Young patients may be at greater risk of long term toxicity, poor compliance, and concerns about peer acceptability of treatment.
    • Intervention risks may be unknown in children.
    • Concomitant medications may have known or unknown interactions with an intervention that make it less safe or less efficacious.