levels of evidence-> scholarship

level 1

evidence from a systematic review or meta-anaylysis of all relavents RCTs

combines results from multiple high quality studies to create one strong conclusion

strong because it gathers the ‘best of the best’ research and analyzes it together

ex: a meta-analysis showing that hand hygiene reduces HAIs

level 2

evidence from well-designed single RCTs (true experimental studies)

participants are randomly assigned to groups to reduce bias→ level playing field

strong because randomization ensures fairness, making results more reliable

ex: one group gets a new BP drug and another gets a placebo

level 3

evidence from single well-designed controlled trials without randomization (quasi-experimental)

similar to RCTs but without random assignment; groups are chosen or naturally formed

weaker than RCTs because there is not randomization, other factors may influence the outcome

ex: comparing two hospital units where one starts a new fall prevention program an the other does not

level 4

evidence from a well-designed case-control and cohort-studies (experimental)

observational studies that look at groups over time (cohort) or compare people with and without a condition (case-control)

moderate because it shows associations, but not strong proof of cause-and-effect

ex: studying whether nurses working night shifts have higher rates of sleep disorders

level 5

evidence from systematic reviews of descriptive and qualitative studies (meta-synthesis)

valuable because it provides deep insight into experiences, feelings, or perceptions, but not cause-and effect

summarizes multiple qualitative or descriptive studies (interviews, focus groups)

ex: a review of studies exploring patients’ of living with chronic pain

level 6

evidence from a single descriptive or qualitative study

one study that explores a phenomenon, behavior, or experiences

lower because good for understanding but based on limited data

ex: interview based study of how new nurses cope with burnout

level 7

evidence from the opinion of authorities, reports from expert committees, narrative/literature reviews

recommendations from experts, organizations, or panels without strong research backing

weakest because it is based on experience, not always on research evidence

ex: a hospital policy created by senior nurses based on their experience