What is the Newcastle-Ottawa Scale?
Short answer
The Newcastle-Ottawa Scale (NOS) is a quality assessment tool for non-randomised studies (cohort and case-control) used in systematic reviews. It scores studies on a star system across three domains: selection (4 stars max), comparability (2 stars max), and outcome/exposure (3 stars max) for a maximum of 9 stars. Scores of 7+ are generally considered high quality.
Execution Steps
- 1Determine if your study is a cohort or case-control design (NOS has separate scales).
- 2Score the selection domain: representativeness, selection of controls, ascertainment of exposure.
- 3Score the comparability domain: comparability of cohorts based on design or analysis.
- 4Score the outcome domain: assessment of outcome, length and adequacy of follow-up.
- 5Sum the stars for an overall quality score (max 9).
Prompt Template
Help me score this cohort study using the Newcastle-Ottawa Scale. The study examined [exposure] and [outcome] in [population] over [time period].
Common Failure Points
- Using the cohort scale for case-control studies (or vice versa)
- Not pre-specifying which confounders to assess in the comparability domain
- Treating the star count as an absolute quality measure without considering domain-specific patterns
FAQ
Composite User Feedback
Medical Student
"The answer pages helped me move from not understanding a paper to knowing which part I should read next."
Clinician
"These guides work because they answer the practical question first, then point me to the workflow I should use."
Medical Librarian
"The strongest pages are the ones that can stand alone as answers and still route people into the right LancetClaw skill."