PubMed Research Rules

Query Construction

Use MeSH terms for precise searching — controlled vocabulary ensures you find related concepts regardless of wording
Boolean operators must be uppercase: AND, OR, NOT — lowercase is ignored
Phrase searching with quotes: "heart failure" not heart failure — unquoted searches terms separately
Field tags narrow searches: [Title], [Author], [MeSH Terms] — example: aspirin[Title] AND prevention[MeSH]
Truncation with asterisk: therap* finds therapy, therapies, therapeutic

Article type matters: Clinical Trial, Systematic Review, Meta-Analysis — filter by study design
Publication date for recent evidence — older studies may be superseded
Free full text filter if access is limited — but don't ignore paywalled high-quality studies
Humans filter excludes animal studies — relevant for clinical questions
Language filter if translation isn't feasible

Systematic reviews and meta-analyses synthesize multiple studies — start here for established topics
Randomized controlled trials (RCTs) are gold standard for interventions — but not all questions are answerable by RCT
Cohort studies for long-term outcomes and rare exposures
Case-control for rare diseases
Case reports are lowest evidence — interesting but not generalizable
Guidelines synthesize evidence into recommendations — check who wrote them and when

Sample size matters — small studies may show effects that don't replicate
Check confidence intervals, not just p-values — narrow CI with meaningful effect size beats p<0.05
Funding source and conflicts of interest affect interpretation — industry-funded studies favor sponsors
Primary vs secondary outcomes — cherry-picking significant secondary outcomes is common
Intention-to-treat vs per-protocol analysis — ITT is more conservative and realistic

Abstract conclusions may oversell results — read methods and results sections
Single studies rarely settle questions — look for replication and systematic reviews
Statistical significance isn't clinical significance — 1% improvement may not matter to patients
Retracted papers still appear in searches — check Retraction Watch for controversial papers
Predatory journals publish low-quality research — verify journal reputation
Preprints haven't been peer-reviewed — useful for speed but not vetted

PICO framework: Patient/Population, Intervention, Comparison, Outcome — structures clinical questions
Start broad, then narrow with filters — missing relevant papers worse than sorting through extras
Save searches for ongoing monitoring — PubMed can email when new papers match
Related Articles feature finds similar papers — useful after finding one good paper
Citation tracking: who cited this paper? — follow research forward in time

Impact factor indicates journal prestige, not individual paper quality
First and last authors typically did the work and led the project
Corresponding author handles questions — contact for clarifications
Check author affiliations — institutional reputation matters
Methods section determines if results are trustworthy — results are only as good as methods

PubMed is free but full text often isn't — check institutional access, Unpaywall, or request from authors
PMID is the unique identifier — use it for precise citations
Export to reference manager (EndNote, Zotero) — manual citation is error-prone
Clinical Queries filter pre-filters for clinical relevance — therapy, diagnosis, prognosis, etiology
Similar Articles and Cited By expand discovery — algorithm finds related work