Course: Research in Biomedicine and Health IIISeminar 3: Looking for evidence

EBM steps◦Step 1: Formulating questions that can be

answered◦Step 2: Finding best evidence◦Step 3: Quick critical assessment of the

evidence◦Step 4: Applying evidence◦Step 5: Assessing effectiveness and

efficiency of the process

“PICOT” model:Patient (For which patient, population or problem you need information?)Intervention/indicator (What is the intervention you are studying?)Comparison/control (Which is the alternative treatment?)Outcome

(What is the effect of the intervention?)Type of study(Which is the optimal study design ?)

Who is treated?

What is given as a treatment?

What is the comparison?

What outcome is of interest to us?

How to ask a clinical question?

What is the study design?

Aim of steps 1. i 2. : find “pearls”

Journals (“Online evidence-based journals of secondary publications”)

Databases(“Evidence-based databases”)

Clinical guidelines (“Online evidence-based clinical practice guidelines”)

Restricted access journals: - ACP Journal Club; http://www.acpjc.orgAvailabe via OVID (CARNet)- Evidence-Based Medicine; http://ebm.bmjjournals.com - Evidence-Based Mental Health;

http://ebmh.bmjjournals.com- Evidence-based Obstetrics and Gynecology;

http://www.harcourt-international.com/journals/ebogFree access journal:- Bandolier; http://www.jr2.ox.ac.uk/bandolier/

The Cochrane Library (http://www.cochrane.org)

The DARE

The Cochrane Controlled Trials Register (CENTRAL)

PubMed Clinical Queries (http://www.ncbi.nlm.nih.gov/entrez/query/static/clinical.shtml)

SUMSearch (http://sumsearch.uthscsa.edu/ )

TRIP Database (http://www.tripdatabase.com )

The National Guideline Clearinghouse (NGC) (http://www.guideline.gov )

Primary Care Clinical Practice Guidelines (http://medicine.ucsf.edu/resources/guidelines/index.html ).

Be precise!

Kew words for database search

PPatient,

problem

Iintervention

CComparison

(not always)

OOutcome

TType of

study

Recommended procedure: Determine key words key words and see if you can find them in

MeSH-u and choose relevant MeSH term for database search.

Decide which question type you are looking for, depending on the purpose (therapy, diagnosis, prognosis etc. ).

Determine study design that is best for your question (RCT, case-control, cohort) (try to find metaanalysis or systematic review)

Choose the database and search it according to relevant key words.

Carefully formulate the question Break the question into individual concepts Break each concept into related terms and synonims Decide on the grammatical form of each term within

a concept Connect all terms within the same concept with OR

operator Combine different concepts with AND operator

Based on PICO(T) model It is not necessary to search each aspect of the clinical

question using the PICO(T) model – this would narrow the search too much.

Search strategy usually has three elements: Terms (MeSH and free key words) which describe health care

condition (population, problem) Terms describing the intervention Terms describing study designs (not used in some databases

which archive only studies of specific study design, like CENTRAL of the Cochrane collaboration)

Sensitivity◦ Aim of such strategy is to find as many papers, even those

that are not very focused on the topic. ◦ It is used when we estimate that the available literature is

not large or when a large number of relevant studies is needed.

Precision◦ Strategy aims to find most important papers.◦ It is defined as the ratio between the number of identified

relevant studies and number of retrieved studies.

Operators are words or signs that have specific function whithin the syntax unit during search.

They determine the relationship between the key words within syntactic units and the whole search strategy.

The make search more precise. Most common are Boolean operators.

◦AND

◦OR

◦NOT

◦ George Boole (1815 – 1864) – English mathematician, developed algebraic system consisting of only two possible states.

Operator Function

AND

Narrows the search Results include only the papers that contall all words or germs linked by the operator

OR

Widens the search Results include all papers containing any of the words or terms linked with the operator Results include papers that contain all used words

NOT

Excludes all papers that contain the word or term behind the operator Should be used carefully Rarely used

1. 1st keyword about patient/disease2. 2nd keyword about patient/disease3. 1 OR 24. 1st keyword about intervention5. 2nd keyword about intervention6. 4 OR 57. 1st keyword about study design8. 2nd keyword about study design9. 7 OR 810. 3 AND 6 AND 9

FIRST CONCEPT

SECOND CONCEPT

THIRD CONCEPT

Nesting is searching for groups of keywords in a single search

Grouping is achieved by brackets Example:

◦(1 OR 2) AND (3 OR 4 OR 5 OR 6) AND (7 OR 8)

FIRST CONCEPT SECOND CONCEPT THIRD CONCEPT

Good search strategy should include both if the database uses a controlled vocabulary such as MeSH.

Terms should be chosen for each concept. Terms can be chosen according to a relevant article,

which is indexed according to MeSH terms. MeSH Database (PubMed) can also be used to

identify relevant terms.

1. Osteoporosis, Postmenopausal/2. osteoporo$.ti,ab. 3. Bone Density/4. (bone adj5 (densit$ OR loss OR mass)).ti,ab. 5. BMD.ti,ab. 6. Fractures, Bone/7. fracture$.ti,ab. 8. OR/1-7

MEDLINE (OVID)1. search$.tw.

2. exp "information storage and retrieval"/ or Medical Informatics/

3. Data Compression/

4. 2 not 3

5. or/1,4

6. quality control/ or Evaluation Studies/ or "reproducibility of results"/

7. (quality adj2 assess$).tw.

8. or/6-7

9. (quality or evaluat$).tw.

10. (precision or recall or sensitivity or relevance or specificity).tw.

11. (performance adj2 (measur$ or indicat$ or assess$)).tw.

12. "Sensitivity and Specificity"/

13. or/10-12

14. (error$ or mistake$ or failure$ or inaccura$ or misspell$).tw.

15. (MeSH or (subject adj2 heading$) or (controlled adj2 vocabulary) or redundan$ orexplod$ or explos$ or spell$ or Medline).tw.16. truncat$.tw.17. (truncat$ adj6 (protein$ or gene$)).mp.18. 16 not 1719. exp Documentation/20. exp Molecular Sequence Data/21. 19 not 2022. or/15,18,2123. EVIDENCE-BASED MEDICINE/24. META-ANALYSIS/25. Review.pt.26. "Review Literature"/27. or/23-2628. "INFORMATION STORAGE AND RETRIEVAL"/st [Standards]29. and/27-2830. and/5,8,1331. and/5,13-1432. and/9,13,2233. or/29-3234. "cochrane database of systematic reviews".jn.35. 33 not 3436. limit 35 to yr=1980 - 2005

Metaanalysis

Systematic review

RCT

Cohort study

Case-control study

Case series/case reports PubMed (MEDLINE)“AND” case report

PubMed (MEDLINE)“AND” case control study

PubMed (MEDLINE)“AND” cohort study

ACP Journal Club / Cochrane Central Register of Controlled Trials

Pubmed (MEDLINE) Clinical Queries (Therapy)

ACP Journal Club / Cochrane Database of Systematic Reviews

Pubmed (MEDLINE) Clinical Queries (Systematic Reviews)

ACP Journal Club / Cochrane Database of Systematic Reviews

Pubmed (MEDLINE) “AND” meta-analysis