Table 4.

Database search results.

Databases	Step 1 result combined with ‘OR' operator	Step 2 result combined with ‘OR' operator	Step 3 result combined with ‘OR' operator	Result of steps 1, 2, and 3 combined with ‘AND' operator
Embase	123,834	9,687	1,211,662	131
Ovid Medline	130,433	12,120	538,190	104
PubMed	179,274	14,951	567,008	219
Total	433,541	36,758	2,316,860	454