2.4.c Boolean operators

iDevice icon Reflection
Are you familiar with the Boolean logic?

PubMed uses some special search rules and syntax.
The Boolean operators (connectors) are words as AND, OR, and NOT.
AND, OR and NOT must be entered always in UPPERCASE.

AND is the default operator used in PubMed!
If you do not include Boolean operators in your search, PubMed will automatically use AND between terms.
PubMed processes Boolean connectors in a left-to-right sequence.

Looking at the previous example:

Should maternal AZT, to prevent MTCT, be started before or after 28 weeks of pregnancy?

P= HIV-positive pregnant woman
I= AZT before 28 weeks
C= AZT after 28 weeks
O= decrease the risk of mother to child transmission

From this PICO, a good search strategy using Boolean might look like:

HIV woman AND (AZT OR zidovudine OR ZDV) 28 weeks AND decreased MTCT