Module 4.3 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

Review the key aspects of applicability below.

Baseline risks

• For prevention studies, does your patient have the same baseline risk as the 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. For example: https://bcrisktool.cancer.gov/
  • 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.

Difference 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.
  • Factors which may affect a trial’s applicability to patients include social status, economic circumstances, their geographic location, sex, gender, ethnicity, disability, or sexual orientation. (1)

1 World Health Organisation [Internet]. Geneva, Switzerland: WHO; c2026. Health equity; [last updated 2021 Jul 7; cited 2026 Feb 4]. Available from https://www.who.int/health-topics/health-equity

Toxicities

• 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.