name: PubMed description: Search and evaluate biomedical literature with effective queries, filters, and critical appraisal. metadata: {"clawdbot":{"emoji":"๐ฌ","os":["linux","darwin","win32"]}}
PubMed Research Rules
Query Construction
- Use MeSH terms for precise searching โ controlled vocabulary ensures you find related concepts regardless of wording
- Boolean operators must be uppercase: AND, OR, NOT โ lowercase is ignored
- Phrase searching with quotes: "heart failure" not heart failure โ unquoted searches terms separately
- Field tags narrow searches: [Title], [Author], [MeSH Terms] โ example: aspirin[Title] AND prevention[MeSH]
- Truncation with asterisk: therap* finds therapy, therapies, therapeutic
Essential Filters
- Article type matters: Clinical Trial, Systematic Review, Meta-Analysis โ filter by study design
- Publication date for recent evidence โ older studies may be superseded
- Free full text filter if access is limited โ but don't ignore paywalled high-quality studies
- Humans filter excludes animal studies โ relevant for clinical questions
- Language filter if translation isn't feasible
Study Hierarchy
- Systematic reviews and meta-analyses synthesize multiple studies โ start here for established topics
- Randomized controlled trials (RCTs) are gold standard for interventions โ 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 โ interesting but not generalizable
- Guidelines synthesize evidence into recommendations โ check who wrote them and when
Critical Appraisal
- Sample size matters โ small studies may show effects that don't replicate
- Check confidence intervals, not just p-values โ narrow CI with meaningful effect size beats p<0.05
- Funding source and conflicts of interest affect interpretation โ industry-funded studies favor sponsors
- Primary vs secondary outcomes โ cherry-picking significant secondary outcomes is common
- Intention-to-treat vs per-protocol analysis โ ITT is more conservative and realistic
Common Traps
- Abstract conclusions may oversell results โ read methods and results sections
- Single studies rarely settle questions โ look for replication and systematic reviews
- Statistical significance isn't clinical significance โ 1% improvement may not matter to patients
- Retracted papers still appear in searches โ check Retraction Watch for controversial papers
- Predatory journals publish low-quality research โ verify journal reputation
- Preprints haven't been peer-reviewed โ useful for speed but not vetted
Search Strategy
- PICO framework: Patient/Population, Intervention, Comparison, Outcome โ structures clinical questions
- Start broad, then narrow with filters โ missing relevant papers worse than sorting through extras
- Save searches for ongoing monitoring โ PubMed can email when new papers match
- Related Articles feature finds similar papers โ useful after finding one good paper
- Citation tracking: who cited this paper? โ follow research forward in time
Evaluating Sources
- 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 โ contact for clarifications
- Check author affiliations โ institutional reputation matters
- Methods section determines if results are trustworthy โ results are only as good as methods
For Specific Questions
- Treatment efficacy: RCTs and systematic reviews first
- Diagnosis accuracy: sensitivity/specificity studies
- Prognosis: cohort studies with long follow-up
- Etiology/harm: cohort or case-control studies
- Prevention: RCTs when available, cohort otherwise
Practical Tips
- PubMed is free but full text often isn't โ check institutional access, Unpaywall, or request from authors
- PMID is the unique identifier โ use it for precise citations
- Export to reference manager (EndNote, Zotero) โ manual citation is error-prone
- Clinical Queries filter pre-filters for clinical relevance โ therapy, diagnosis, prognosis, etiology
- Similar Articles and Cited By expand discovery โ algorithm finds related work
Red Flags in Papers
- No control group for intervention studies
- Conclusions not supported by data presented
- Missing or inadequate statistical analysis
- Selective reporting of outcomes
- Conflicts of interest not disclosed
- Extraordinary claims without extraordinary evidence